A /A Luiza Gut

A  /A Luiza Gut
ASSESSMENT OF
A PARTIAL NITRITATION/ANAMMOX SYSTEM
FOR NITROGEN REMOVAL
Luiza Gut
January 2006
TRITA-LWR Licentiate Thesis 2034
ISSN 1650-8629
ISRN KTH/LWR/LIC 2034-SE
ISBN 91-7178-167-6
Luiza Gut
TRITA LWR LIC 2034
ii
Assessment of a partial nitritation/Anammox system for nitrogen removal
Att skapande är att befria det som redan finns.
Henning Mankell
”Berättelse på tidens strand”
iii
Luiza Gut
TRITA LWR LIC 2034
iv
Assessment of a partial nitritation/Anammox system for nitrogen removal
Summary
Nitrogen removal from wastewater has been introduced in Sweden and in many other countries
mainly by the implementation of a technology based on biological nitrification and denitrification
processes. One vital factor negatively affecting the wastewater treatment in the biological nitrification/denitrification step is the recirculation of a nitrogen-rich stream originating from dewatering of digested sludge (supernatant). Separate treatment of the supernatant is often proposed to
decrease the nitrogen load into the main stream. However, such type of wastewater contains
small amounts of biologically degradable carbon compounds and the addition of an external
carbon supply is necessary to perform treatment in the traditional nitrification/denitrification
processes.
In the 1990s, a cost-effective deammonification process was proposed to separately treat ammonium-rich streams. In the first step of the deammonification process, equal amounts of ammonium and nitrite nitrogen are produced in the partial nitritation route to perform in the second
stage the ANaerobic AMMonium OXidation (Anammox®) process. The latter step involves
simultaneous biochemical removal of ammonium and nitrite by Anammox bacteria under oxygen-limited conditions, and results in the production of dinitrogen gas. The deammonification
system, which is still under development, can be designed to perform this process in either one
or two reactors. This novel wastewater treatment technology enables considerable savings
through reduced aeration costs and elimination of the necessity for an external carbon source.
In Sweden, a technical-scale pilot plant continuously supplied with the supernatant was constructed and operated at the Himmerfjärden WWTP, Grödinge. A focus was given to perform
the deammonification in two steps in a moving-bedTM biofilm partial nitritation/Anammox system®. As biofilm carriers, Kaldnes rings were used.
In this study, the successful establishment of the partial nitritation process was shown. The efficient nitrogen removal in the Anammox reactor was obtained under the two-year period. The
Anammox reactor capacity was extended and the pH correction was excluded. The performance
data were collected and evaluated in accordance with the system approach by means of univariate
and multivariate data analyses.
As a result of this assessment, the interplay of the factors affecting both steps of the system (such
as pH value, dissolved oxygen (DO) concentration, temperature, conductivity, nitrite concentration) was recognised and a control system has been proposed. The control strategy for the system
consisted of adjusting the relevant factors (DO concentration, drop of the pH value) to obtain
the nitrite-to-ammonium ratio (NAR) around 1.3 in the effluent from the partial nitritation reactor (R1). The effective nitrogen removal in the Anammox reactor (R2) was dependent on the
performance of the preceding step and monitoring of the nitrite nitrogen concentration in the
reactor. The dissolved oxygen concentration and nitrite nitrogen concentration increase were
recognised as system bottlenecks. The influence of the influent supernatant characteristics on the
process performance was evaluated as well. The study demonstrated that both aerobic and anaerobic oxidation of ammonium occurred in the R1 and R2 reactors, respectively, and could be
monitored by conductivity measurements. An Oxygen Uptake Rate (OUR) test methodology for
the nitrifying biofilm cultures has been developed. OUR tests regarding the nitrifying activity of
the bacteria in both steps of the system were performed and evaluated. Batch tests enabled to
estimate the reaction rates.
Assessment of the partial nitritation/Anammox system gave recommendations for future fullscale implementation. An array of process options has been proposed. Case-specific technological improvements of a two-step partial nitritation/Anammox system have been presented. A
possibility of Simultaneous Partial Nitritation/Anammox (SPNA) system has been suggested for
future investigations.
v
Luiza Gut
TRITA LWR LIC 2034
vi
Assessment of a partial nitritation/Anammox system for nitrogen removal
Sammanfattning
Avlägsnande av kväve från avloppsvatten har införts i Sverige och i många andra länder främst
med hjälp av en teknologi som baseras på de biologiska processerna nitrifikation och denitrifikation. En viktig faktor som inverkar negativt på avloppsreningen i det biologiska steget är recirkulationen av kväverika flöden som kommer från avvattningen av slam (rejektvatten). Separat behandling av ammoniumrika rejektvatten har föreslagits för att minska kvävemängden till
huvudflödet. Traditionella biologiska kväveavskiljningssystem som är utformade för att rena
avloppsvatten med hög ammoniumhalt kan bli mycket dyra, särskilt om avloppsvattnet innehåller
små mängder av biologiskt nedbrytbara kolföreningar så att tillförsel av en extern kolkälla är
nödvändig.
Under 1990-talet påbörjades utveckling av en kostnadseffektiv process för separat rening av
ammoniumrika flöden med deammonifikationsprocessen som alternativ till det traditionella nitrifikations- och denitrifikationssystemet. I det första steget av deammonifikationsprocessen produceras approximativt lika stora mängder av ammonium och nitritkväve i nitritationsprocessen för
att sedan fortsätta i ett andra steg med Anammox®. Det sista steget medför samtidig biokemisk
avskiljning av ammonium och nitrit med hjälp av Anammoxbakterier under anaeroba förhållanden och resulterar i produktion av kvävgas. Deammonifikationssystemet, som fortfarande är
under utveckling, kan utformas i antingen en eller två reaktorer. I denna studie ligger fokus på att
utföra deammonifikationen som en två-stegs process med systemet partiell nitritation/Anammox®.
I Sverige vid Himmerfjärdens avloppsreningsverk (Grödinge) har bedrivits försök i en pilotanläggning i teknisk skala som kontinuerligt tillförs rejektvatten från reningsverket. Försök genomfördes med partiell nitritation och Anammox som tvåstegsteknik med biofilmsteknik (“movingbedTM”). Kaldnesringar användes som bärare för biofilmen.
Studien redovisar ett lämpligt sätt att erhålla partiell nitritation. I det efterföljande andra steget
kunde anammoxreaktionen erhållas stabilt och med god effektivitet i två år. Faktorer beskrivs
som påverkade anammoxreaktorns kapacitet och tillsats för pH-justeringar kunde undvikas. Data
för utvärdering av driftdata insamlades systematiskt med hänsyn till användning av univariat- och
multivariatanalys.
Till följd av utvärderingen har studerats faktorers interaktion som påverkar bägge steg av systemet (t.ex. pH-värde, syrehalt (DO), temperatur, konduktivitet, nitritkvävehalt) och kontrollsystem
har föreslagits. Systemstrategin bestod i justering av relevanta faktorer (syrehalt, minskning av
pH-värde) för att erhålla en kvot mellan ammonium och nitrit (NAR) på drygt 1,3 i avloppet från
den partiella nitritationprocessen (R1). En effektiv kväveborttagning i Anammox reaktorn (R2)
berodde på det partiella nitritationstegets utförande och övervakning av nitritkvävekoncentration
i Anammoxreaktorn. DO koncentration och nitritkvävehaltens ökning var identifierade som
processflaskhalsar. Inverkan av inkommande rejektvattnets egenskaper i processen utvärderades
även. Undersökningar visade att både aerob och anaerob ammoniumkväveoxidation i R1 respektive R2 kan övervakas med hjälp av konduktivitetsmätningar. Testmetodik för Oxygen Uptake
Rate (OUR) (syreupptagningshastighet) för nitrifikationsbakterier i biofilm utvecklades. OUR
tester angående bakteriernas aktivitet i Anammox steget i bägge steg av systemet utfördes och
utvärderades. Diskontinuerliga tester möjliggjorde beräkning av reaktionshastighet.
Utvärdering av det partiella nitritation-Anammox systemet gav underlag för anvisningar för att
utföra ett system i full skala i framtiden. Processutformningar har föreslagits och även tekniska
förbättringarna av ett partiellt nitritation-Anammox system. Möjligheter att etablera ett samtidigt
utnyttjande i enbart ett steg av partiell nitritation och Anammox har föreslagits för fortsatta studier.
vii
Luiza Gut
TRITA LWR LIC 2034
viii
Assessment of a partial nitritation/Anammox system for nitrogen removal
Acknowledgements
I would like to express my gratitude to my supervisor Associate Professor Elżbieta Płaza to give me
the opportunity to be where I am today in the professional development. I appreciate your encouragement, support and devoting your time for discussions and “brain-storming”.
I wish to thank my co-supervisor Professor Bengt Hultman. Your great ability to put things into a
wider perspective has certainly helped me in the research work. I admire your knowledge and creativity.
This licentiate work was carried out within the deammonification project with the financial support
from SYVAB, VA-FORSK, J. Gust Richert Foundation and PURAC. Lars Erik Lundbergs Foundation financed my scholarship.
I appreciate enthusiasm and the love to science of the former Director of the Himmerfjärden WWTP
Alf-Göran Dahlberg who initiated the project. Enormous gratitude goes to Jan Bosander, Senior
Process Engineer at the Himmerfjärden WWTP and the expert in ALL the practical things. Both he
and the staff at SYVAB AB created an unforgettable working environment. Thank you for that a lot!
I thank Dr. Józef Trela for the leadership of the deammonification project and discussions concerning the research. Beata Szatkowska and Grzegorz Cema were two other Ph.D. students involved in
the deammonification project and sharing with me experimental and analytical work. Beata, thank you
for more than 2 years of the side-by-side work in the deammonification project. I find our friendship
that naturally developed along the hard work at KTH as a precious gift from God. I am grateful to
Grzegorz Cema for help in developing the OUR tests and the following experiments, and I respect
your pursuit for knowledge.
The Polish-Swedish cooperation resulted in many valuable formal and informal discussions. I deeply
appreciate comments and advice of Dr. Stanisław Rybicki, Associate Professor Joanna SurmaczGórska, Professor Korneliusz Miksch and Professor Krystyna Mędrzycka.
Personal communications with Professors H. Siegrist and M.C.M. van Loosdrecht are appreciated.
Professor M. Sjöström from the Umeå University, Dr. R. Torgrip from the Stockholm University, J.
Röttorp and E. Furusjö from the IVL Swedish Environmental Research Institute helped me in the
modelling part of my thesis. The research groups from the Göteborg University and the Delft University of Technology performed the FISH analyses. I acknowledge your contributions.
Many people at the Department of Land and Water Resources Engineering deserve my gratitude.
Hereby I would like to thank especially Monica Löwén for being so patient and creative in putting
new research ideas into the laboratory practice. Maja, I watched your development from the time of
being Master Student until becoming Ph.D. student. I admire your strength, intellect and warm heart,
and I thank you for support and friendship. Alexandra, I appreciate your help in discovering ”the
mysteries” of modelling rules and thank you for your kindness. I am also exceptionally grateful to
Jerzy Buczak for the help with the computer problems! Master of Science students contributed to the
experimental part of this thesis. Thanks go to Maja, Basia and Kuba. Be always so enthusiastic and
brave! Giampaolo, I thank you for friendliness.
I am indebted to the strong Polish community in Stockholm that was a great help in the homesick
feeling. Thanks to you I felt almost like home – Kasia W. with her mother Halina, Bercia with the
family, Iza with the family, Asia, Kasia K. and Piotr. To Ania Kieniewicz, my classmate, roommate
and most importantly my friend, I thank you to be with me through the time of sorrow and joy.
Please, do not ever change! I left also a lot of friends in Poland. I miss you all and thank you for not
forgetting about me and encouraging me!
All the EESI students influenced me a lot. I hereby thank especially Crafton, Annika and Berta. I
have also met here kind Swedes – thanks for all Tomas, Tommy and Malin! Ian, thank you for devoting your time to revise English in my thesis.
Most of all, my family deserves the biggest appreciation. To my Mother, Father, Brother and Grandparents – thank you for support, encouragement and LOVE. You are the dearest people to me in the
whole world. I love you everlastingly.
ix
Luiza Gut
TRITA LWR LIC 2034
x
Assessment of a partial nitritation/Anammox system for nitrogen removal
TABLE
OF
C ONTENT
Summary ........................................................................................................................................ v
Sammanfattning ........................................................................................................................... vii
Acknowledgements ....................................................................................................................... ix
Appended papers ...................................................................................................................xiii
Abstract...................................................................................................................................... 1
1. Biological nutrient removal – a sustainable approach ....................................................... 1
2. Objectives of the thesis......................................................................................................... 3
3. New concepts in nitrogen removal from wastewater......................................................... 3
3.1. Background...................................................................................................................... 3
3.2. Ammonium-rich streams.................................................................................................. 4
3.3. Overview of processes with nitrogen removal .................................................................. 9
3.4. Applications of the Anammox process........................................................................... 18
3.5. Modelling of the systems with biological wastewater treatment ...................................... 21
4. Methodology ....................................................................................................................... 22
4.1. Pilot plant description .................................................................................................... 22
4.2. System configurations and operational approach............................................................ 23
4.3. Measurements and analytical procedures ........................................................................ 24
4.4. Batch tests...................................................................................................................... 25
4.5. Oxygen Uptake Rate (OUR) tests................................................................................... 25
4.6. Modelling of the process data with the SIMCA-P software ............................................ 26
5. Results and discussions...................................................................................................... 27
5.1. Bacterial identification and activity ................................................................................. 27
5.1.1. FISH tests........................................................................................................................... 27
5.1.2. Application of OUR tests.................................................................................................... 28
5.2. Factors affecting system efficiency ................................................................................. 29
5.2.1. Supernatant characteristics .................................................................................................. 30
5.2.2. Partial nitritation process..................................................................................................... 31
5.2.3. Anammox process .............................................................................................................. 33
5.2.4. Reaction rates...................................................................................................................... 35
6. Implications for full-scale implementation....................................................................... 36
6.1. Proposal for system configurations ................................................................................ 36
6.2. System technology with partial nitritation/Anammox .................................................... 40
6.3. Overall recommendations .............................................................................................. 40
7. Final conclusions ................................................................................................................ 43
8. Further research work......................................................................................................... 44
9. References ........................................................................................................................... 45
xi
Luiza Gut
TRITA LWR LIC 2034
xii
Assessment of a partial nitritation/Anammox system for nitrogen removal
A PPENDED
PAPERS
This thesis is based on the following papers, which are appended at the end of this thesis and
referred to by their Roman numerals in the thesis text:
I.
Gut L., Płaza E., Długołęcka M. and Hultman B. (2005) Partial nitritation process assessment. Vatten, 61(3), 175-182.
II.
Gut L., Płaza E. and Hultman B. (2005) Oxygen Uptake Rate (OUR) tests for assessment
of nitrifying activities in the deammonification system. In: Integration and optimisation of urban
sanitation systems, Joint Polish-Swedish Reports, No 12. Royal Institute of Technology, Stockholm, 2005, TRITA-AMI.REPORT, in press.
III. Gut L., Płaza E., Trela J., Hultman B. and Bosander J. (2005) Combined partial nitritation/Anammox system for treatment of digester supernatant. In: Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 1921 September 2005, Kraków, Poland, 465-474.
IV.
Gut L., Płaza E. and Hultman B. (2005) Assessment of a two-step partial nitritation/Anammox system with implementation of multivariate data analysis. Submitted to:
Chemometrics and Intelligent Laboratory Systems.
xiii
Luiza Gut
TRITA LWR LIC 2034
xiv
Assessment of a partial nitritation/Anammox system for nitrogen removal
Abbreviations
Anammox – anaerobic ammonium oxidation
ASL – ammonium surface load
BAF – bench-scale upflow biological aerated filter
CANON – completely autotrophic nitrogen removal over nitrite
DO – dissolved oxygen
FBR – fixed-bed reactor
FISH – fluorescent in situ hybridisation
HRT – hydraulic retention time
MBBR – moving-bed™ biofilm reactor
MVDA – multivariate data analysis
NAR – nitrite-to-ammonium ratio
OLAND – oxygen-limited autotrophic nitrification-denitrification
OUR – oxygen uptake rate
p. e. – population equivalent
PCA – principal component analysis
PLS – partial least squares projections to latent structures
SBR – sequencing batch reactor
SHARON – single reactor system for high ammonium removal over nitrite
SPNA – simultaneous partial nitritation/Anammox
SRT – sludge retention time
SS – suspended solids
USAB – upflow anaerobic sludge blanket
VSS – volatile suspended solids
WWTP – wastewater treatment plant
Chemical notations
ATU – allylthiourea
COD – chemical oxygen demand
HNO2 – nitrous acid
NaClO3 – sodium chlorate
NH3 – free ammonia
NH4-N – ammonium nitrogen
NO2-N – nitrite nitrogen
NO3-N – nitrate nitrogen
N2O – nitrous oxide
NO – nitric oxide
NO2 – nitric dioxide
NOx = N2O, NO & NO2
xv
Luiza Gut
TRITA LWR LIC 2034
xvi
Assessment of a partial nitritation/Anammox system for nitrogen removal
A BSTRACT
This thesis evaluates the performance of a deammonification system designed as a two-step technology consisting of an initial partial nitritation followed by an Anammox process. Operation of
a technical-scale pilot plant at the Himmerfjärden Wastewater Treatment Plant (Grödinge, Sweden) has been assessed. Oxygen Uptake Rate (OUR) to evaluate the respiration activity of nitrifiers in the system and batch tests to assess reaction rates have also been applied in the study. It
was found that the total inorganic nitrogen elimination strongly depended on the nitrite-toammonium ratio in the influent to the Anammox reactor, which was correlated with the performance of the partial nitritation phase. Therefore, a control strategy for oxidation of ammonium to nitrite has been proposed. Controlled oxygen supply to the partial nitritation reactor is
obligatory to obtain a proper pH drop indicating oxidation of ammonia to nitrite at the adequate
ratio. A very high nitrogen removal efficiency (an average of 84%) and stable operation of the
system have been reached. Conductivity measurements were also used to monitor the system
influent nitrogen load and the nitrogen removal in the Anammox reactor. The data gathered
from the operation of the pilot plant enabled the use of multivariate data analysis to model the
process behaviour and the assessment of the covariances between the process parameters. The
options for full-scale implementation of the Anammox systems have been proposed as a result of
the study.
Key words: Biofilm; Deammonification; Nitrogen removal; Oxygen Uptake Rate (OUR); Partial
nitritation/Anammox system
as drawn up in the Directive 91/271/EEC,
recently gave rise to an amending Directive
98/15/EC in February 1998. The total nitrogen discharge limit for plants with more than
100,000 p.e. is equal to 10 mg l-1 with 70-80
minimum percentage of reduction whereas
for total phosphorous 1 mg l-1 (80 percent of
minimum reduction).
At the end of the twentieth century, biological nutrient removal became a standard
wastewater treatment option. Gradually, the
traditional method of using nitrification/denitrification route in nitrogen removal
has encountered difficulties in coping with
the more stringent effluent standards imposed on existing wastewater treatment
plants (WWTP). The influent load often
increases and contributes to employ an upgrading procedure, which now is a common
solution to increase the capacity of a WWTP.
In many cases, however, the upgrading of a
plant requires space that is not available.
Hybrid systems have been proposed to improve the activated sludge system (Gebara,
1999; Ochoa et al., 2002). Carriers for biofilm
growth have been used to enhance the existing processes and increase the capacity without expansion of the reactor footprint (Øde-
1. B IOLOGICAL NUTRIENT
REMOVAL – A SUSTAINABLE
APPROACH
Currently, an increasing awareness of the
need for sustainable water management results in an effort to reduce the load of nutrients imposed on receiving water bodies. A
variety of factors are nowadays taken into
account in order to decide on proper wastewater treatment systems. Population growth
and more stringent effluent standards are
amongst factors that play a vital role in
choosing the most appropriate options for
wastewater handling. An emphasis has been
put on reducing the expenditure for aeration
and chemical additions.
The European Union Water Framework
Directive 91/271/EEC imperatively states to
“protect the environment from any adverse
affects due to discharge of (untreated) urban
and industrial waters”. In this perspective the
development of new technologies for finding
solutions in water management is of highest
concern for both stakeholders and citizens.
The requirements for discharges from urban
wastewater treatment plants to sensitive
areas, which are subjected to eutrophication,
1
Luiza Gut
TRITA LWR LIC 2034
gaard et al., 1994, 2000; Orantes and González-Martínez, 2003).
For further improvements, one has to identify the bottlenecks that are part of the existing systems. In the traditional nitrification/denitrification process, the generated
sludge is digested and centrifuged at a
WWTP and an ammonium-rich side stream
is produced (digester supernatant). The supernatant contains as much as 2 kg N m-3
(Strous et al., 1997). Typically, it is recirculated to the inflow of a WWTP and contributes to the increase of the influent nitrogen
load by 15-20% in comparison with the total
influent nitrogen load (Płaza et al., 1989,
1990; Jansen et al., 1993; Jönsson et al.,
2000). Separate collection and treatment of
supernatant from digested sludge is now a
promising alternative. In Sweden, more than
10 wastewater treatment plants have a system
of full-scale separate supernatant treatment,
mainly with activated sludge SBR-technology
and nitrification/denitrification processes.
Studies by Tendaj-Xavier (1985) and Mossakowska
(1994)
performed
at
KTH/Stockholm Water are examples of
research works concerning the biological
treatment of supernatant.
With the discovery of the Anammox bacteria
(Mulder et al., 1995), new feasibility studies
concerning implementation of the Anammox
process into the existing infrastructure have
been evaluated. It was shown that if the main
component of the digester supernatant –
ammonium nitrogen – was partially oxidised
to nitrite in a preceding step, the Anammox
bacteria could use nitrite as an electron acceptor and anaerobically convert ammonium
and nitrite to nitrogen gas (Jetten et al., 1997).
Sliekers et al. (2004) proposed a combination
of aerobic nitrifying bacteria and anaerobic
Anammox bacteria to treat urea in one single
reactor.
Separate collection of urine is of highest
interest nowadays (Jetten et al., 1997; Maurer
et al., 2003; Wilsenach et al., 2003; van Loosdrecht et al., 2004). There is a new branch of
research that focuses on treating urine, as it is
the main source of nutrients in municipal
wastewater. If successful, such sustainable
handling of wastewater will result in the
reduction of nitrogen and phosphorous loads
in WWTPs. The residual part of the nutrients
would therefore be used up completely for
the generation of sludge. In this most probable case, all the nitrogen would be released
as supernatant after sludge digestion and its
treatment would be the most significant part
of the treatment at a WWTP. Such a shift in
wastewater management would put much
more emphasis on establishing a reliable
system for biological treatment of sludge
liquors. Moreover, application of the Anammox process will prove to be important in
the future perspective as it can actually be
applied for treatment of supernatant, urine
and other ammonium-rich streams like
leachates.
In the field of environmental technology, the
concept of treating many types of side
streams currently receives a lot of attention.
There is further potential for the implementation of the Anammox process to treat
separately collected urine (Maurer et al., 2003;
Sliekers et al., 2004), landfill leachate (Hippen, 2001; Hippen et al. 2001; Nikolić and
Hultman, 2003), poultry and piggery waste
thin fractions (Dong and Tollner, 2003; Ahn
et al., 2004), and many industrial side streams.
Among industrial wastewater there are examples of treating slaughterhouse wastewater
(Keller et al., 1997), pharmaceutical streams
(Carrera et al., 2003), tannery wastewater
(Banas et al., 1999; Carruci et al., 1999),
streams from the food and beverage industry
(Austermann-Haun et al., 1999) and potato
processing industries like alcohol and starch
production (Abeling and Seyfried, 1992).
Despite considerable concentrations of organic matter, usually expressed as COD
(Chemical Oxygen Demand), these streams
need to be treated with the external supply of
easy biodegradable organic carbon to sustain
the denitrification process.
The prospect of implementing a research idea
in a full scale requires adequate questions to
be answered successfully. A biological process has to be developed to give reliability in
practice. Interdependence between conditions for proper bacterial growth and lowcost treatment might be an obstacle in reaching the expected treatment expenditures’
2
Assessment of a partial nitritation/Anammox system for nitrogen removal
reduction. However, a biological system
depended on autotrophic reactions may lead
to savings on addition of chemicals. Additionally, the biofilm moving-bed systems
have the advantage of compactness and low
excess sludge production. Moreover, system
reactions need to be scrutinized for side
effects in accordance with characteristics of
supernatant to be treated.
2. O BJECTIVES
cally favourable as the aerobic nitrification
process. It was only recently that this reaction
was proven in a laboratory (Mulder et al.,
1995; Strous et al., 1997; Helmer et al., 1999,
2001; Jetten et al., 1999; Seyfried et al., 2001).
The research group from the Kluyver Laboratory for Biotechnology at the Delft University of Technology, the Netherlands, discovered anaerobic ammonium oxidizers
(Anammox bacteria) in a fluidised bed reactor (Mulder et al., 1995). More comprehensive research concerning the Anammox
started around the 1990s and publications
concerning the process and its technology
were released. Initially, the nomenclature was
a little ambiguous and in the Anammox-related publications the term ‘deammonification’ was used to describe the novel process
of nitrogen removal. A proposal for a more
sustainable wastewater treatment system was
made (Jetten et al., 1997) and consisted of
treating wastewater in two steps.
A partial nitritation reactor was designed to
pre-treat wastewater with the aim of producing a proper feed to the Anammox reactor. The application of the SHARON (Single
reactor system for High Ammonium Removal Over Nitrite) reactor in which the reaction is stopped at partial oxidation of the
ammonia to nitrite (‘partial’ SHARON) was
suitable for supplying the Anammox reactor.
The digester supernatant was chosen to be
the stream most adequate for applying the
combination of the SHARON and Anammox processes. The processes for the treatment of ammonium-rich wastewater were
patented (Mulder, 1992; van Loosdrecht and
Jetten, 1997, 2003; Dijkman and Strous,
1999). A consultant company Paques (Paques
home page), which specialises in the development and manufacture of biological water
purification systems, developed the Anammox process for commercial purposes. The
SHARON® process has been patented by
“Grontmij Water and Waste Management”
(Heijnen and van Loosdrecht, 1997, 1999).
It was also proven that the Anammox bacteria largely contribute (up to 70%) to nitrogen
cycle in the World's oceans (Thamdrup and
Dalsgaard, 2002; Dalsgaard et al., 2003, 2005;
Devol, 2003; Kuypers et al., 2003). At
OF THE THESIS
This licentiate work focuses on biological
nitrogen removal with the use of a two-step
partial nitritation/Anammox process. The
objectives are:
•
To perform a literature study concerning
different system designs for the most
cost-effective nitrogen removal from
ammonium-rich wastewater.
•
To evaluate a two-step partial nitritation/Anammox system with the aim of
establishing stable partial oxidation of
ammonium to nitrite in the first step and
effective removal of nitrogen in the second step.
•
To assess the influence of a variable
characteristics of supernatant from dewatering of digested sludge, as an ammonium-rich stream, on the system performance.
•
To assess the presence of a nitrifying
activity in the system in both a quantitative and qualitative manner.
•
To prepare recommendations for an
integrated and efficient biological system
for the treatment of nitrogen-rich
streams.
3. N EW
CONCEPTS IN
NITROGEN REMOVAL FROM
WASTEWATER
3.1. Background
It was almost three decades ago that Brodda
(1977) predicted the existence of chemolithoautotrophic bacteria using only thermodynamic calculations. It was demonstrated that
the biological uptake of ammonium as an inorganic electron donor is nearly as energeti3
Luiza Gut
TRITA LWR LIC 2034
Skagerrak, which is part of the Danish belt
seaway, it was shown that Anammox reaction
has a large importance in the N2 production.
At greater depths, where the sediment mineralisation rates are lower, the importance of
Anammox in removing the nitrogen in the
sediments seems to be highest (Dalsgaard et
al., 2005). The natural occurrence of Anammox bacteria was also proven in marine
sediments of the Thames estuary (Trimmer et
al., 2003), in Golfo Dulce in Costa Rica
(Dalsgaard et al., 2003), in freshwater wetland
in Africa (Jetten et al., 2003) as well as in
arctic sediments (Rysgaard et al., 2004).
Strous et al. (1999) reported that Planctomycetales could perform the Anammox process.
Currently, three genera of Anammox bacteria
have been discovered: Brocadia, Kuenenia and
Scalindua. Genera of Brocadia and Kuenenia
occur naturally in ammonium-rich environments and have been found in wastewater
treatment systems. Candidatus Brocadia anammoxidans (Mulder et al., 1995; Jetten et al.,
2001) and Candidatus Kuenenia stuttgartiensis
(Egli et al., 2001) were identified by the FISH
(Fluorescent In-Situ Hybridisation) method.
The biodiversity of Anammox bacteria was
extended by the discovery of a genus Scalindua at a WWTP treating landfill leachate in
Pitsea, UK (Schmid et al., 2003). Two species
were found: Condidatus Scalindua brodae and
Scalindua wagneri. The genus of Scalindua has
been also detected in the marine ecosystems
of the Black Sea and the Candidatus was
named Scalindua sorokinii (Kuypers et al.,
2003). A brown-reddish colour is typical for
all Anammox bacteria probably due to its
high cytochrome content (Jetten et al., 1999).
Environmental and possibilities of economical advantages of these discoveries are substantial, and therefore give rise to large
expectations in the future usage of naturally
occurring Anammox bacteria in wastewater
treatment technology. The first full-scale
Anammox reactor at the Dokhaven WWTP,
Rotterdam, the Netherlands was started in
2002 (Abma et al., 2005). At Hattingen
WWTP, Germany a full-scale deammonification pilot plant with the Kaldnes moving-bed
process is in operation (Jardin et al., 2001;
Cornelius and Rosenwinkel, 2002; Rosen-
winkel and Cornelius, 2005). Furthermore, at
the Strass WWTP, Austria the deammonification single sludge SBR system was implemented on full scale.
Publications within this area of research are
mainly from Europe with the leading centres
being in the Netherlands and Germany. In
Sweden, the most important research groups
are in Stockholm (wastewater technology)
and in Gothenburg (marine microbiology).
At the Royal Institute of Technology, Stockholm, at the Department of Land and Water
Resources Engineering there is an extensive
research concerning technological aspects of
the combined partial nitritation/Anammox
system for digester supernatant treatment. It
was initiated by SYVAB AB and PURAC AB
in 2000. An overview of the research and
commercial groups with a focus on the
branch of research concerning the Anammox
process is shown in Table 1.
3.2. Ammonium-rich streams
The data gathered in Table 2 shows the general characteristics of different ammoniumrich streams. It is mainly supernatant and
landfill leachate that have been studied by
different researchers. These streams differ
from each other in the concentration of
organic matter (expressed as COD). It is
characteristic for supernatant to have a higher
temperature compared to the raw wastewater
at the inflow to a WWTP (Glixelli, 2003).
The supernatant is a product of dewatering
of the sludge that was earlier stabilised by the
process of methane fermentation. Such
sludge is usually characterised by a high percentage of mineral substances – products of
fermentation. It is periodically disposed of
the digestion chamber and dewatered in
centrifuges or filter presses. The handling of
supernatant causes a common problem in
large wastewater treatment plants where
anaerobic digestion of sludge is used. High
concentrations of NH4-N from the supernatant added at the inflow to the WWTP
overload the biological nitrogen removal
process. Despite the fact that the volumetric
supernatant flow is 3-5% of the influent
wastewater flow, the ammonium content in
such a stream may be as high as 15-20% of
4
Assessment of a partial nitritation/Anammox system for nitrogen removal
Table 1. Overview of the research and development of the Anammox process.
Country/centre
the Netherlands
Delft University of Technology
University of Nijmegen
Royal Netherlands Institute for
Sea Research
Germany
University of Hannover
Technical University of
Munich
Max Planck Institute For
Marine Microbiology
Belgium
Ghent University
Austria
University of Vienna
University of Innsbruck
Denmark
Technical University of
Denmark
University of Southern
Denmark
National Environmental
Research Institute
University of Aarhus
United Kingdom
Cranfield University
University of Birmingham
University of London
Switzerland
Swiss Federal Institute of
Technology (EAWAG), Zurich
Spain
University of Santiago de
Compostela
University of Cantabria
Turkey
Istanbul Technical University
Main topics
Examples of references
Microbiology, application of the Anammox
process, full-scale and pilot-plant
experiments; physiology of the Anammox
bacteria, marine microbiology, biomarkers for
detection of Anammox bacteria; the IcoN
(Improved control and application of nitrogen
cycle bacteria for Nitrogen removal from
wastewater) project
Microbiology, application of the Anammox
process, physiology of the Anammox bacteria,
marine microbiology
Marine microbiology (the impact of Anammox
on the past oceanic nitrogen cycle)
van Loosdrecht and Jetten
(1998); Kuenen and Jetten
(2001); Schmidt el. (2003);
Sliekers et al. (2003); Strous et
al. (2002); Strous and Jetten
(2004); IcoN project web page
Deammonification biofilm moving-bed
technology (full-scale and pilot-plant
application)
Hippen et al. (1997); Helmer et
al. (1999, 2001); Seyfried et al.
(2001); Rosenwinkel and
Cornelius (2005); Rosenwinkel
at al. (2005)
University of München web
page
Kuypers et al. (2003)
Microbiology, application of the Anammox
process, physiology of the Anammox bacteria
Marine microbiology
Jetten et al. (1997, 1999, 2002)
Sinninghe-Damsté et al. (2002)
Modelling, simulation, optimisation,
technological aspects of Anammox process,
the IcoN project
Verstraete and Philips (1998);
Pynaert et al. (2002); Volcke et
al. (2002); Van Hulle (2005);
IcoN project web page;
BIOMATH web page
Marine microbiology, application of the
Anammox process
Deammonification activated sludge SBR
technology (full-scale and pilot-plant
application)
Schmid et al. (2005); University
of Vienna web page
Wett (2005)
Technological aspects of Anammox process
Anammox process in marine environment
Dalsgaard and Thumdrup
(2002); Dalsgaard et al. (2003,
2005)
On-line sensors for Anammox control
Ottosen et al. (2004)
Microbiological studies
Cranfield University web page
Mohan et al. (2004)
Trimmer et al. (2003)
Microbiology in estuarine sediments
Technological aspects of Anammox process,
application of the Anammox process
Siegrist et al. (1998); Egli et al.
(2001); Fux et al. (2002); Egli
(2003); Fux (2003)
Application of the Anammox process,
inhibition studies, enrichment, modelling; the
IcoN project
Model-based evaluation of the Anammox
process
Dapena-Mora et al. (2004,
2005)
Stimulation of the Anammox activity; inhibition
studies
Güven et al. (2004, 2005)
5
Domínguez et al. (2005)
Luiza Gut
TRITA LWR LIC 2034
Table 1. Overview of the research and development of the Anammox process (contd).
Country/centre
France
Genoscope, Evry, the
French National Sequencing
Center
Sweden
Royal Institute of
Technology, Stockholm
Göteborg University
Poland
Silesian University
Australia
University of Queensland
Murdoch University
USA
University of Georgia
USA/Brazil
Coastal Plains, Soil, Water
and Plant Research Center,
United States Department of
Agriculture
Japan
Kumamoto University
Nagaoka University
Korea
Korea University
Kyungpook National
University
Yeungnam University
China
Beijing Institute of Civil
Engineering and
Architecture
Tsinghua University
Hunan University
Main topics
Examples of references
Genetic information concerning Anammox
bacteria
Genoscope web page
Deammonification moving-bed technology;
technical-scale and lab-scale pilot plant studies;
one-set and two-step technology; modelling
studies
Marine microbiology
Płaza et al. (2002); Szatkowska
(2004); Szatkowska et al.
(2003a,b; 2004a,b); Trela et al.
(2004a,b,c); Gut et al. (2005)
Engström (2004)
Kinetics of the Anammox process; technological
aspects of Anammox process, application of the
Anammox process (laboratory-scale
experiments)
Surmacz-Górska et al. (1997);
Cema et al. (2005a,b)
Molecular microbial ecology of the Anammox
bacteria
Anammox process in the CANON system
University of Queensland web
page
Third et al. (2001); Third (2003)
Application of the Anammox process for poultry
manure
Dong and Tollner (2001)
Application of the Anammox process for
livestock wastewater
United States Department of
Agriculture web page
Granulation of the Anammox bacteria,
application of the Anammox process
Molecular Biological Analysis of Anammox,
laboratory-scale experiments
Furukawa et al. (2001); Imajo et
al. (2004)
Nagaoka University web page
Application of the Anammox process for piggery
waste
Ahn et al. (2004); Hwang et al.
(2004)
Modelling of a partial nitritation-Anammox
biofilm process; laboratory-scale experiments
Hao and van Loosdrecht (2003,
2004)
Granulation of the Anammox bacteria;
laboratory-scale experiments
Start-up of the deammonification process;
laboratory-scale experiments
Anammox process technology; laboratory-scale
experiments
Jianlong and Jing (2005)
Harbin Institute of
Technology
Ocean University of China
University of Science and
Enrichment and cultivation of Anammox
Technology of Suzhou
microorganisms
Commercialization of the technology
Paques BV, the Netherlands Full-scale implementation of Anammox; the IcoN
project
Grontmij Water and
Coupling SHARON with the Anammox process
Reststoffen, the Netherlands
PURAC AB, Sweden
Technical-scale pilot plant studies,
deammonification studies
Unisens A/S, Denmark
Construction and use of micro and macro scale
nitrogen-sensors for environmental analysis of
the Anammox process
Kurita Water Industries Ltd.,
Commercial application of the Anammox
Japan
process; pilot-scale experiments of Anammox
process
6
Li et al. (2004)
Wang et al. (2004)
Huang et al. (2004)
Paques home page
Grontmij Water and Reststoffen
web page
Johansson et al. (1998)
Unisense A/S web page
Kurita Water Industries Ltd. Web
page
Assessment of a partial nitritation/Anammox system for nitrogen removal
the raw wastewater load (Siegrist, 1996; Wett
and Alex, 2003). Pre-treatment of such supernatant is necessary to lower the nitrogen
load. Different deammonifying systems running with this medium as a substrate were
investigated in many works (Table 2).
Recently the debate concerning the impact of
waste landfills has put more interest in the
second source of high ammonia waste
streams – leachate. The leachate is concentrated and highly polluted water that soaked
through the solid waste layer of landfill,
transporting suspended solids and extracting
soluble substances and other products of
complex degradation processes in the landfill.
Biochemical conditions, seasonal water regime of the landfill and changes in the solid
waste composition affect both the quality and
the quantity of this wastewater. Removal of
ammonium is often not sufficient by treatment
using
a
biological
nitrification/denitrification method. Moreover, the
nitrifying bacterial community is sensitive to
toxic substances and high concentrations of
ammonium. A seasonal decrease in the temperature can be a major drawback in the
implementation of leachate treatment systems in the Northern European countries.
The flow variations at a WWTP and at a
landfill site can cause changes in the quality
of both media. The leachate water quality
slowly changes with the landfill age. On the
other hand, the supernatant’s quality is affected by operating problems with fermentation chambers or differences at the inflow to
a WWTP (for instance the uneven flow of
rainwater influences its operation). Yet, in the
long run this is the medium with the most
stable composition. Ammonium nitrogen
concentration in leachate changes during a
landfill’s life and it can exceed 2000 mg NH4N l-1. Fluctuations of ammonium nitrogen
concentration in supernatant can be high
(from 400 to 1700 mg NH4-N l-1) and change
in a matter of days or weeks. Because of this,
it is necessary to control the treatment system
in terms of changeable influent medium
characteristics. Amounts of other inorganic
nitrogen forms, like NO2-N and NO3-N, are
very low in both types of waters. Minor concentrations of organic nitrogen forms are
present in both supernatant and leachate as
the ratio of NH4-N/Ntot usually falls just
below 1 (Glixelli, 2003). The pH value is
similar in both media. The amounts of COD
are usually much higher in the leachate, although in some cases the supernatant can
have a COD concentration larger than 1000
mg O2 l-1. The total phosphorus concentration in leachate is usually low and stable
during the landfill’s existence (in the range
0.1-19.4 mg Ptot l-1). In the supernatant, its
concentration changes to a higher extent
(0.6-48.6 mg Ptot l-1). An additional advantage
of the supernatant and the leachate is their
high temperature, though the leachate’s temperature is more difficult to control and
depends more on seasonal changes. Glixelli
(2003) also reported the presence of other
substances in leachate, like heavy metals,
trace elements or toxic substances.
It is the location (standard of life, industry
located in the municipal area) and the characteristics of waste treated at a municipal
WWTP or a landfill (e.g. pre-treatment of
solids waste) that affects the quality and
quantity of both the supernatant and the
leachate. A technology used in the wastewater treatment also determines the composition of the supernatant (i.e. supernatant from
the chemical sludge is usually rich in metal
salts used for precipitation). Moreover, it is
of special importance to separate the supernatant stream from the other side streams
generated at a WWTP, e.g. scrubber water
and water from the cleaning of centrifuges
(they may cause operational problems as well
as being a source of toxic substances).
It was also recently proposed to independently treat urine collected in separating toilets
(NoMix toilets) or waterless urinals (Jetten et
al., 1997; Maurer et al., 2003). Urine is a
major source of nitrogen, phosphorous and
potassium in municipal wastewater and is a
prime target to achieve a more sustainable
treatment of nutrients today. During storage,
the pH value of urine increases and therefore
it is higher than the pH value of the supernatant. A high concentration of the total
phosphorous differs urine from supernatant
and leachate. Autotrophic processes were
employed to treat urine, mainly traditional
7
Luiza Gut
TRITA LWR LIC 2034
Table 2. Literature overview of different studied ammonium-rich streams (nd - no data).
Stream
Supernatant
NH4-N
-1
(mg l )
1000
T
o
( C)
30
pH
(-)
8.1-8.4
COD
-1
(mg O2 l )
810
27
1180
nd
6.7-6.8
nd
nd
750
30
nd
277
840
nd
nd
657
nd
5001500
Ptot
-1
(mg l )
Comments
References
nd
Influent to Sharon
reactor
SharonAnammox
process
BABE reactor
1044
nd
SBR reactors
7.4-7.8
nd
0.6-7.3
30-37
7.0-8.5
nd
nd
1200
30
7.2
710
nd
Partial nitritation/
Anammox system
SharonAnammox
process
RBC system
Hellinga et
al. (1998)
van Dongen
et al.
(2001b)
Salem et al.
(2003)
Fux et al.
(2003)
Fux et al.
(2002)
Jetten et al.
(1997)
12501700
5521004
30-35
700-1000
nd
SBR reactor
nd
11.912.8
nd
384-711
1.2-33
436-797
nd
7.4-7.9
262-650
19.4-48.6
15402310
23-27
7.9-9.8
1940-5704
11.8-19.4
0.2-800
nd
5.2-8.7
180-4700
0.7-6.5
0.7-1520
nd
6.9-9.5
470-7200
0.1-13.6
32-681
18-494
147-780
27-30
13-20
10-28
7.4-8.7
7.3
7.2-8.8
442-2900
nd
748-1593
220-260
nd
7.0-7.2
nd
nd
Partial nitritation/
Anammox system
(Sweden)
Assessment of
digester
supernatant
(Poland)
Assessment of
leachates
(Taiwan)
Assessment of
leachates
(Sweden)
Assessment of
leachates
(Poland)
RBC systems:
Mechernich,
Germany;
Kölliken,
Switzerland;
Pitsea, UK
RBC system
8180
nd
nd
nd
670
18003800
nd
8.9-9.1
nd
80
(after
precipitation)
4300
nd
8.4-8.6
56000
476-1260
950
nd
nd
3000
210
Leachate
nd
Urine (urea)
Piggery
manure
Potato
starch
wastewater
8
Energetic aspects
of removal and
recovery of
nutrients
MMBR (nitrate
production),
CSTR, SBR
(nitritation),
Anammox batch
reactor
Granular sludge
UASB reactor
Activated sludge
nitrification/
denitrification via
nitrite
Beier et al.
(1998)
Wett et al.
(1998)
Szatkowska
(2004)
Musiał
(2000)
Chen
(1996)
Welander
(1998)
Obrzut
(1997)
Hippen et
al. (2001)
Siegrist et
al. (1998)
Maurer et
al. (2003)
Udert et al.
(2003)
Ahn et al.
(2004)
Abeling and
Seyfried
(1992)
Assessment of a partial nitritation/Anammox system for nitrogen removal
nitrification, Anammox and CANON (Udert
et al., 2003; Sliekers et al., 2004). Urine handling aims at producing ammonium/nitrate
solutions for fertilizing purposes and removing nitrogen in the partial nitritation/Anammox route.
Due to the enhanced production of piggery
manure, the handling option has been proposed as an alternative of using it as the soil
fertilizer. The thin fraction of the piggery
manure can be treated and the application of
the Anammox process has been successful
(Ahn el al., 2004; Choi et al., 2004). The
composition of the thin fraction of the piggery waste varies significantly and depends
on the equipment used for separating thick
and thin fractions of the sludge. High
amounts of nitrogen, COD and total phosphorous are typical for this kind of wastewater.
Industrial processes also generate highly
concentrated nitrogen streams and should be
treated separately. Abeling and Seyfried
(1992) name the following industry fields as
producers of wastewaters with high inorganic
nitrogen concentration: alcohol production,
pectin industry, starch and potato processing
industry, slaughterhouses, metallurgy and
petrochemical industry. High COD concentration in these wastewaters is not always
sufficient for denitrification. Moreover, industrial streams often contain toxic compounds that hinder the biological treatment
processes.
many different chemical and biochemical
routes for the nitrogen transformation to
nitrogen gas. Table 3 shows an overview of
the most important processes in handling the
nitrogen load imposed on WWTPs. The
ultimate aim is to transform the ammonium
to nitrogen gas with the least usage of resources and without formation of greenhouse
gases like nitrous oxide (N2O). The paradigm
that the only way to biologically convert the
wastewater ammonium to nitrogen gas is
through the aerobic conversion to nitrate
followed by the heterotrophic denitrification
is now obsolete. Discoveries of other metabolic paths of aerobic and anaerobic ammonia oxidizers are now used in the environmental biotechnology. A short outline of the
processes follows (the reaction numbers refer
to Table 3).
Traditional nitrification/denitrification
In Table 3 the traditional treatment system
with the combination of nitrification and
denitrification is illustrated by the reactions
4+5+6+7. At Swedish WWTPs, the nitrogen
removal technology is consuming a considerable amount of resources: 4.57 g O2 g-1 N and
around 4 g COD g-1 N (Płaza, 2001; Trela,
2000). These values imply that there is a need
to aerate the medium for nitrification and
supply an external source of carbon for denitrification. It has to be taken into account
that the internal content of easily biodegradable COD changes in different countries.
The traditional biological treatment leads to a
sizeable amount of produced sludge that
must be treated in a proper manner. An
efficient execution of the anoxic denitrification demands a variety of electron donors,
such as acetate, methanol, ethanol, lactate or
glucose (Henze et al., 2002). Dissimilar conditions for bacteria performing nitrification
and denitrification result in designing separate reactors for both processes. This leads to
high costs of construction, operation and
maintenance of the biological part of a
WWTP.
Subsequent
nitrification/denitrification is possible in the Sequential Batch Reactor (SBR) by alternating the
conditions in a proper sequence of aerobic
and anoxic phases.
3.3. Overview of processes with nitrogen
removal
At a municipal WWTP, the influent ammonium is mainly the product of breaking down
proteins. During the biological treatment a
negligible part of the ammonium is transformed to ammonia in the gas phase. Moreover, ammonia is partly used by the activated
sludge and biofilm bacteria and contributes
to their organic biomass. That part of the
ammonium nitrogen is only temporarily
bounded due to the subsequent release of
ammonium during the fermentation process
(the sludge handling part of a WWTP) and
results in the generation of a highly concentrated side stream of reject water. There are
9
Luiza Gut
TRITA LWR LIC 2034
Table 3. Reactions for biological conversions of nitrogen forms (modified after Płaza et al.,
2003).
No.
Reaction
Process
1a
C5H7O2N+4H2O → 2.5CH4+
+
1.5CO2+HCO3 +NH4
Ammonification
(anaerobic)
Bacteria
1b
C5H7O2N+5O2 →
+
4CO2+HCO3 +NH4 +H2O
Ammonification
(aerobic)
Bacteria
Ammonium/
ammonia
equilibrium
No (physical
process)
Assimilation
Bacteria, Algae
(growth)
-
+
2
NH4 +OH → NH3 +H2O
3
4CO2+HCO3
+
+NH4 +H2O →
C5H7O2N+5O2
4
NH4 +1.5O2+
2HCO3 →
NO2 +2CO2+3H2O
5
NO2 +0.5O2 → NO3
-
+
-
+
4+5
Nitritation
-
Nitratation
-
NH4 +2O2+2HCO3 →
NO3 +2CO2+3H2O
-
-
Nitrification
6
C+2NO3 → 2NO2 +CO2
Denitratation
7
3C+2H2O+CO2+
4NO2 →2N2+4HCO3
Denitritation
-
6+7
5C+2H2O+4NO3 →
2N2+4HCO3 +CO2
Denitrification
+
8
NH4 +0.75O2+
+
HCO3 → 0.5NH4 +
0.5NO2 +CO2+1.5H2O
9a
NH4 +NO2 → N2+2H2O
+
+
9b
4+7
4+5+6+7
4+9
10
11
-
-
NH4 +1.32NO2 +
0.066HCO3 →
1.02N2+0.26NO3 +
0.066CH2O0.5N0.15+2.03H2O
+
4NH4 +6O2+3C+
4HCO3 →
2N2+7CO2+10H2O
+
4NH4 +8O2+5C+4HCO3 →
2N2+9CO2+10H2O
NH3+0.85O2 →
+
0.11NO3 +0.44N2+0.14H +
1.43H2O
+
NH4 +0.75O2 →
+
0.5N2+H +1.5H2O
+
3NH4 +3O2+3[H] →
+
1.5N2+3H +6H2O
Microorganisms
Nitrosomonas, e.g.
N. eutropha, N.
europea;
Nitrosospira
Nitrobacter, e. g.
N. agilis,
Nitrospira,
Nitrococcus,
Nitrosocystis
References
Rittmann and
McCarty (2001);
Henze et al.
(2002)
Nitrifying bacteria
Denitrifying
heterotrophic
bacteria
Denitrifying
heterotrophic
bacteria
Heterotrophs:
Pseudomonas,
Bacillus,
Alcaligenes,
Paracoccus
Partial nitritation
Ammoniumoxidizing bacteria
Anammox (without
cell synthesis)
Planctomycetales
Anammox (with cell
synthesis)
Planctomycetales
Modified nitrogen
removal
Bacteria
Traditional nitrogen
removal
Bacteria
Rittmann and
McCarty (2001);
Henze et al.
(2002)
CANON
Nitrifying bacteria,
Planctomycetales
Sliekers et al.
(2002)
OLAND
Nitrosomonas
NOx process
Nitrosomonas
10
van Dongen et al.
(2001a)
Verstraete and
Philips (1998)
Schmidt et al.
(2003)
Assessment of a partial nitritation/Anammox system for nitrogen removal
allows for longer aerobic and shorter anoxic
phases (Hellinga et al., 1998). During the
anoxic phase, methanol is added and the
denitrification proceeds. Compared to the
traditional
processes
of
nitrification/denitrification, the oxygen demand is
decreased by 25% and amounts to 3.43 g
O2/g N. To compare the usage of the organic materials, it is decreased by 40%, which
equals 2.4 g COD/g N (Mulder et al., 2001;
Hellinga et al., 1998). The sludge production
is also lower and a simple well-mixed reactor
can be used. Six full-scale SHARON units
have been constructed at WWTPs in Rotterdam, Utrecht, Zwolle, Beverwijk, Garmerwolde and Den Haag, the Netherlands (total
capacity 2,740,000 p.e.) and a plant is under
construction in New York, USA (3,000,000
p.e.) (van Loosdrecht and Salem, 2005).
It appeared that characteristics of the recycled reject water streams are especially suitable to partially oxidize ammonium to nitrite
in the ‘partial’ SHARON as the supernatant
contains about equimolar amounts of ammonium and bicarbonate. The carbon dioxide stripping could therefore balance the
nitrite production by a concurrent pH drop,
preventing further oxidation. The nitrite/ammonium ratio in the effluent from
the ‘partial’ SHARON reactor can be consequently influenced by pH control (van Dongen et al., 2001a). The ‘partial’ SHARON
concept can also be used as the preceding
step for the Anammox process. The ‘partial’
SHARON process can be modified with the
goal of obtaining proper effluent quality,
which is an essential factor for the appropriate operation of an Anammox reactor. It is
discussed further in the next section.
Modifications of traditional N-removal processes
The oxidation of ammonium to nitrite (reaction 4) followed by denitritation (reaction 7)
has been the subject of extensive research
(Turk and Mavinic, 1989; Surmacz-Górska et
al., 1997; Jianlong and Ning, 2003; Ruiz et al.,
2003; Wyffels et al., 2003; Ciudad et al.,
2005). The minimisation of resources by
partial nitrification and denitrification results
in a more sustainable technology. Savings in
the oxygen demand, reduction of the organic
carbon requirement and the decrease in the
surplus sludge are advantages of shortcutting
the traditional nitrification/denitrification
route. Nitrite accumulation is obtained by
optimising the operational conditions by
properly setting the parameters like the dissolved oxygen (DO), pH value and temperature (Hwang et al., 2000; Bae et al., 2002;
Ruiz et al., 2005). The system set-up can
consist of performing partial nitrification and
partial denitrification in two steps (Ruiz et al.,
2005) or using a one-stage activated sludge
system (de Silva and Rittmann, 2001). Additionally, nitrite accumulation techniques were
applied for low concentrated streams mainly
(de Silva and Rittmann, 2001; Bae et al.,
2002). However, high ammonium concentration wastewaters have also been treated
(Wyffels et al., 2003; Yang et al., 2003; Ciudad et al., 2005; Ruiz et al., 2005).
SHARON process
The SHARON (Single reactor system for
High Ammonium Removal Over Nitrite)
process (reaction 8) was designed to reduce
the load of streams with high ammonium
concentration (ca. 1 g NH4-N l-1) rather than
meet effluent standards. Conditions set in the
SHARON reactor favour ammonium oxidizers by washing out nitrite oxidizers due to the
short retention time (approximately 1 day)
and a temperature over 30oC (van Dongen et
al., 2001a). A full-scale SHARON reactor
operates at the Dokhaven WWTP, Rotterdam, the Netherlands (van Dongen et al.,
2001b; van Kempen et al., 2001). Initially, the
process concept was aimed at exploiting the
specific temperature of supernatant from the
digested sludge and its composition.
A full-scale application is operated with intermittent aeration in one reactor, which
Anammox process
The anaerobic ammonium oxidation
(Anammox) process is a promising pathway
for removing nitrogen from wastewater
(Mulder et al., 1995; van de Graaf et al., 1995;
Dijkman and Strous, 1999; van Dongen et al,
2001a; Strous et al., 1999; van Loosdrecht et
al., 2004). The anaerobic character of the
process (reaction 9) allows for considerable
savings and no addition of chemicals are
needed. The ammonium reacts with the
nitrite acting as an electron acceptor to pro11
Luiza Gut
TRITA LWR LIC 2034
duce nitrogen gas. Intermediates of the process are hydrazine and hydroxylamine (Jetten
et al., 2001). The catabolic reaction of fixing
nitrite with one molecule of carbon dioxide
leads to the anaerobic production of nitrate
in the anabolism (Strous et al., 1998).
According to Van Niftrik et al. (2004), it is
typical for the Anammox bacteria, which
belong to the phylum Planctomycetales, to have
an intracytoplasmic compartment: anammoxosome. The exact function of the anammoxosome is currently under study and it is
strongly believed to play a major role in the
Anammox metabolism.
According to the stoichiometry of the reaction proposed by van Dongen et al. (2001a,
2001b) the nitrite nitrogen concentration
should exceed the ammonium nitrogen concentration in the feed to the Anammox reactor. Thus, a quotient NO2-N/NH4-N is equal
to 1.32. It was demonstrated that the Anammox bacteria have very low growth rate (Jetten et al., 2001) and equals 0.003 h-1. This is
the main obstacle in the process implementation in full scale. A doubling time of 11 days
(Jetten et al., 1999) is a challenge in terms of
starting-up an Anammox reactor. van Dongen et al. (2001b) show that it takes between
100 and 150 days for the Anammox activated
sludge reactor to reach its full capacity. It has
been reported however, that the doubling
time would be closer to a month in full-scale
application due to the kinetics of the process
(Fux et al., 2002, 2004). It would imply a
longer start-up period.
Methods for accelerating the acclimation of
the Anammox bacteria as well as the recovery
of its culture deserve a special interest. Li et
al. (2004) reported the influence of the
Anammox reaction intermediate, hydrazine,
on speeding up the acclimating process.
Egli et al. (2001) demonstrated that the
Anammox bacteria found in a WWTP are
active at temperatures within the range of 643oC and an optimum at 37oC. For the optimal temperature, the pH range is between 6.5
and 8.5. In the natural conditions of sea
sediments, the optimal temperature was
found to be substantially lower and
amounted to 15oC (Dalsgaard and Thamdrup, 2002). The Anammox process is re-
versibly inhibited by oxygen and irreversibly
by nitrite at concentrations exceeding 70 mg
NO2-N l-1 for several days (van Dongen et al.,
2001a). In case of Candidatus Kuenenia stuttgartiensis, the nitrite nitrogen concentration in
the reactor can be raised to 180 mg NO2-N l-1
(van de Graaf et al., 1996; Strous et al., 1999).
This nitrite inhibition can be overcome by
the addition of trace amounts of either of the
Anammox intermediates: hydrazine and
hydroxylamine (Strous et al., 1999; Li et al.,
2004). The exposure of the Anammox bacteria to even low concentrations of alcohols,
methanol in particular, should be prevented
due to the immediate, complete, and irreversible inhibition of the process (Güven et
al., 2005). This research is highly relevant as
methanol is often used to remove nitrate in
the post-denitrification or to compensate for
pH effects in partial nitrification. The results
of a study by Schmidt et al. (2002a) provide
strong indications that the anaerobic ammonia-oxidizing Planctomycetales (B. anammoxidans)
are not sensitive to NO concentrations up to
600 ppm and that the nitrogen conversion
rates of an Anammox reactor system increase
about twofold in the presence of 50 ppm of
NO2.
Feasibility studies about the granulation of
the Anammox bacteria show that the high
applicability to the wastewater treatment
(Imajo et al., 2004, Schmidt et al., 2004). The
granular sludge is maintained in reactor and
such configuration is set in a flow-up reactor.
This technique can result in shorter start-up
periods due to using methanogenic granules
as carrier material in the initial phase. Additionally, Jianlong and Jing (2005) presented
applicability of an expanded granular sludge
bed (EGSB) in the granulation of the
Anammox bacteria.
Research about the Anammox process is
nowadays directed towards defining the biochemical reaction with its intermediates as
well as investigating the possibility of formation detrimental intermediate emissions of
NO and N2O. New microbiological techniques for identifications of the Anammox
bacteria are under development.
12
Assessment of a partial nitritation/Anammox system for nitrogen removal
taining a mixed biocoenosis that coexists in
the biofilm. The shear forces caused by the
intense mixing limit the formation of the
biofilm structure that allows for the development of anoxic zones. The moving-bed
biofilm reactor (MBBR) with the Kaldnes®
biofilm carriers was extensively applied in the
development of the deammonification process (Seyfried et al., 2002; Trela et al., 2004b,c;
Rosenwinkel and Cornelius, 2005).
Combined partial nitritation/Anammox processes –
deammonification process
The least resource consuming method to
transform ammonium to nitrogen gas is the
technology based on partial nitritation/Anammox processes. Anammox needs
a preceding process to convert half of ammonium to nitrite (reaction 4), without subsequent oxidation of nitrite to nitrate. The
oxygen uptake based on initial ammonium
concentration is 1.72 g O2 g-1 N or just 38%
of the oxygen demand for oxidation of all the
ammonium to nitrate. After this process, the
Anammox process (reaction 9) follows without need for organic material in a separate
reactor. Modifications of the SHARON
process (‘partial’ SHARON) by not supplying
methanol and excluding anoxic periods are
an alternative to generate the ammonium/nitrite mixture for the Anammox reactor. The crucial factor is the stoichiometrically correct ratio of nitrite to ammonium.
This should be equal to 1.3 in the influent of
the Anammox reactor (van Dongen et al.,
2001a, 2001b; Volcke et al., 2003).
The research group at the University of
Hanover introduced the ‘deammonification’
term in order to differentiate a novel process
of nitrogen removal from the traditional
denitrification observed in a rotating-disk
plant treating leachate (Hippen et al., 2001).
This term is also used to describe an ammonium removal process that does not depend
on the supply of organic matter (Hippen et
al., 1999, 2001; Helmer et al., 2001; Seyfried
et al., 2002; Rosenwinkel and Cornelius,
2005). It employs aerobic and anaerobic
ammonia oxidizers in converting the ammonia directly to nitrogen gas under oxygen
limitation. Over time, it became apparent that
the deammonification could be defined as a
combination of nitritation and Anammox
processes occurring in the biofilm and established in two separate reactors as well as in
one single reactor. During the start-up of a
single-stage deammonification process, it is
necessary to develop a nitrifying biofilm
culture in aerobic conditions to allow the
Anammox bacteria to enrich the culture
while the conditions are alternated into oxygen-limited. Such a procedure results in ob-
CANON process
A new process configuration that allows for
the combination of nitrifying cultures and
Anammox bacteria was named the Completely Autotrophic Nitrogen removal Over
Nitrite (CANON) process (reactions 4+9,
Table 3). It is based on the concept of simultaneous nitrification and denitrification
(SND) in the same reactor vessel at constant
operating conditions (Keller et al., 1997;
Surmacz-Górska et al., 1997; Helmer and
Kunst, 1998; van Benthum et al., 1998; Yoo
et al., 1999; van Loosdrecht et al., 2000;
Third, 2003). With the discovery of the
Anammox bacteria, the CANON process
was proposed (Sliekers et al., 2002, 2003) and
anaerobic ammonium oxidizers were used as
denitrifies. Oxygen-limited conditions are
obligatory to obtain the cooperation between
aerobic and anaerobic bacteria. A sequencing
batch reactor (SBR) was used to develop the
CANON process (Third et al., 2001; Sliekers
et al., 2002). Unlike the Anammox process,
the CANON process can be fed directly with
an ammonium-rich influent at an appropriate
loading rate. In one reactor, nitrite oxidizers
can be outcompeted due to differences in the
affinity constants between nitrifying bacteria.
In a biofilm bacterial culture it is possible to
achieve a concurrent accumulation of nitrite
in the outer aerobic part of the biofilm layer
and attain Anammox reaction in the inner
anaerobic part of the biofilm (Hao et al.,
2002b; Hao and van Loosdrecht, 2003). Hao
et al. (2002b) modelled this cooperation of
bacteria in the biofilm layer. Schmidt et al.
(2002b) assessed the harmonious and balanced interaction between the two groups of
bacteria. Nitrosomonas can supply Brocadia
anammoxidans with nitrite as an oxidant at the
oxic-anoxic biofilm interface. The coopera13
Luiza Gut
TRITA LWR LIC 2034
tion seems possible despite the natural competition for the same substrate – ammonium.
It is Nitrosomonas that limits the Anammox
process in the CANON reactor configuration
due to its role in preventing diffusion of
oxygen into the deeper layers as well as supplying nitrite to the Anammox bacteria (Nielsen et al., 2005). However, according to the
Gibbs free energy calculations, the Anammox
bacteria should be more efficient than the
Nitrosomonas.
A novel nomenclature for the combination
of partial nitritation and Anammox processes
in one reactor was recently established: Single-stage Nitrogen Removal Using Anammox
and Partial Nitritation (SNAP) process (the
SNAP process web page). It is a wholly autotrophic nitrogen removal process using acryl
resin fibre as a biomass carrier.
somonas strains have a versatile metabolism
and are able to gain energy during the aerobic
and anaerobic ammonia oxidation or by
denitrification using hydrogen or organic
compounds as electron donors (Poth and
Focht, 1985; Bock et al., 1995). Schmidt and
Bock (1997) argue that the anaerobic ammonia oxidation by Nitrosomonas is dependent on
the nitrogen dioxide (NO2). The conversion
of about 50% of the ammonia load to nitrite
occurs and the nitrite produced is used as a
terminal electron acceptor, which leads to N2
production (reaction 11, Table 2). The Nitrosomonas eutropha consumes ammonia and NO2
at the ratio of approximately 1:1 (Schmidt
and Bock, 1997). An equivalent amount of
NO is produced. Then, during denitrification
of nitrite to N2 small amounts of N2O are
produced. Trace amounts of gases NO and
NO2 (NOx) can be added to induce a shortened nitrification/denitrification route by
Nitrosomonas and can therefore be the regulatory signal for the denitrification activity.
NO2 concentrations of up to 50 ppm have
no toxic effects on Nitrosomonas eutropha but
NO at concentration above 25 ppm inhibit
the ammonia oxidation (Schmidt and Bock,
1997).
Consequently, in the NOx process, the nitrification part is more efficient due to a 50%
lower oxygen demand whereas the following
step demands up to 80% less organic matter
for denitrification (Schmidt et al., 2002a).
There is a possibility of implementing this
process in the existing treatment facilities
with minimal financial efforts and minor
changes in the operation strategy (Schmidt et
al., 2003).
OLAND process
Other publications concerning the unexplained nitrogen losses in full-scale denitrifying biofilm reactors led researchers to the
development of the OLAND (OxygenLimited
Autotrophic
NitrificationDenitrification) process. Unlike the CANON
process, the ammonia-oxidizing bacteria are
able to convert ammonium to nitrogen gas in
one reactor under oxygen limitation (Kuai
and Verstraete, 1980; Verstraete and Philips,
1998; Pynaert et al., 2002). The Nitrosomonas
species can use, due to shortage of an electron acceptor, the produced nitrite (reaction
10, Table 3). A pH-controlled aeration of the
enriched autotrophic nitrifiers forces bacteria
to consume nitrite (Verstraete and Philips,
1998).
For practical purposes, the OLAND process
could be easily applied due to the uncomplicated production of nitrifying inoculums
from the activated sludge. This system does
not need the direct supply of nitrite and the
ammonium-rich stream can be treated directly. However, the current system capacity
is still low.
BABE process
Bio-augmentation was postulated as an option for upgrading existing WWTPs by the
treatment of nitrogen-rich flows (Salem et al.,
2003, 2004). The so-called BABE® (bioaugmentation batch enhanced) process aims
at boosting the development of the nitrifying
community by shortening the SRT in the reactor. The enhanced population of nitrifiers
from the BABE reactor is used to feed a
conventional activated sludge system. The
effect of seeding the main nitrification reactor with separately cultivated culture was
NOX process
Schmidt et al. (2003) presented a new possibility of stimulating and controlling the activity of the Nitrosomonas-like microorganisms by
the addition of nitrogen oxides. The Nitro14
Assessment of a partial nitritation/Anammox system for nitrogen removal
studied previously (Płaza et al., 2001) and
focused on treatment of the digester supernatant. The nitrification capacity can be substantially increased by the side-treatment of
supernatant due to both the decreased influent load on the WWTP and the enhanced
activity of the nitrifiers. The improvement of
the effluent quality, creation of extra capacity
and better potential for dealing with peak
loads is also achieved.
Van der Zandt et al. (2005) report that the
BABE process costs 1.75 Euro per kg of
total N removed (2005), which corresponds
to a 60% reduction of costs. In the Netherlands, the full-scale application of the process
that treats reject water exists at the Garmerwolde WWTP, Groningen, and the outing of
the next application is due September 2005
(the ‘s-Hertogenbosch WWTP).
Bio-augmentation may be of special interest
in a partial nitritation/Anammox system as
both nitritation and Anammox bacteria can
be seeded into the main wastewater stream.
sessment of the sustainability factors is given
in Table 5. The objective of conserving energy and resources is met in the case of
SHARON, Anammox, CANON and
OLAND processes. The operability is a great
advantage of the new processes. Even
though the research studies have shown that
it is possible to suppress nitrification at the
level of nitrite formation (‘partial’
SHARON), there is still quite high uncertainty in applying this process on a full scale,
as it is in the developing phase. A necessity is
to scrutinise for possible undesirable side
effects, e.g. highly reactive nitrite can react
with aromatic molecules to produce nitrosoand nitro-derivatives.
Smaller and more compact installations can
be used for the new processes. Special applicability for highly concentrated ammonium
wastewater brings the wastewater management nearer to the source, which diminishes
the impact from a sewer system. Moreover,
the trend to keep the streams as concentrated
as possible (e.g. collection of urine) has to be
integrated with the consumption patterns, i.e.
taking into account all parts of the system. As
the sludge production is reduced to a minimum in the systems with the Anammox
process, only the sludge from the nitrification/denitrification processes and processes
for removal of organic compounds needs to
be handled. The amount of the excess sludge
will be substantially reduced if separate
treatment of supernatant is employed. The
new investigated concepts can be implemented in the existing infrastructure without
difficulties (van Loosdrecht et al., 1997;
Mulder, 2003). The examples of process
selection cases can be found in van Loosdrecht and Salem (2005).
It can be stated that the combined partial
nitritation/Anammox system is one of the
most economical ways of removing nitrogen
in a WWTP. In Table 6 the cost estimation
of two applications were considered: a conventional nitrification/denitrification process
and a novel combined partial nitritation/Anammox system. Fux (2003) performed the cost analysis for the separate
treatment of sludge digester effluents of a
WWTP for 100,000 p.e. The operational
Comparison of the processes
The evaluation of the most important processes for nitrogen removal from wastewaters
is presented in Table 4. Compared to the
well-recognized combination of nitrification
and denitrification, novel processes can be
established in only one reactor. Considerable
savings on aeration (energy) and chemical
addition are typical for the SHARON and
Anammox processes. Due to the fact that the
Anammox process demands a preceding
step, it was proposed to shorten the nitritation process using the ‘partial’ SHARON
concept. Due to a very low growth rate, the
Anammox bacteria need to be retained in the
system. An advantage is the minor formation
of excess sludge but the start-up period is
long. The maintenance costs are reduced as
well as the investment costs due to higher
compactness of the reactors and there is no
need for sophisticated devices for the process
control.
The information concerning wastewater
treatment processes for nitrogen removal is
summarized in Table 4. It shows that there is
a need to consider the application of novel
processes on a full scale. The detailed as15
Luiza Gut
TRITA LWR LIC 2034
Table 4.Qualitative and quantitative comparison of several processes of nitrogen
removal technology, modified after Mulder (2003) and Schmidt et al. (2003) (d.w. – dry weight).
Process/factor
Conventional
nitrification/
denitrification
SHARON
Anammox
CANON
OLAND
Number of
reactors
2
1
1
1
1
Discharge
NO3 , N2O, N2
NH 4 , NO2, N2
N2, NO3
Conditions
Oxic; anoxic
Oxic/anoxic
Anaerobic
Oxygen-limited
Oxygen-limited
Oxygen demand
-1
(kg O2 kg N)
High
(4.6)
Low
(3.4)
None
Low
(1.5-2)
Low
(1.5-2)
pH control
Yes
None
None
None
None
Biomass
retention
None
None
Yes
Yes
Yes
COD
requirement
Yes
Yes
None
None
None
Sludge/biomass
production
–1
(kg d.w. kg N)
High
(1-1.2)
Low
(0.8-0.9)
Low
(<0.1)
Very low
Very low
N-removal
efficiency (%)
95
90
90
90
85
Suspension/
biofilm
Suspension/
biofilm/granules
Biofilm
Biofilm
Aerobic NH4
oxidizers,
N. eutropha,
heterotrophs
Planctomycetales:
Brocadia
anammoxidans,
Kuenenia
stuttgartiensis,
Scalindua brodae,
S. wagneri, S.
sorokinii
Aerobic NH4
oxidizers,
Planctomycetales
Autotrophic
nitrifiers
-
Bacterial growth Biofilm/ suspension
+
-
+
+
-
N2, NO3
-
N2
+
Type of bacteria
NH4 and NO2
oxidizers,
Various
heterotrophs
Process
complexity
Separate oxic and
anoxic
compartments or
periods, methanol
dosing
Separate oxic
and anoxic
compartments
or periods,
methanol
dosing
Preceding partial
nitritation needed
Aeration tuned
to ammonia
loading
Aeration tuned
to ammonia
loading
Application
status
Established
Four full-scale
plants
Two full scale
plants
Laboratory
Laboratory
Availability of
performance
data
High
Medium
Medium
Low
Very low
Investment
costs
High
Medium
Low
Medium
Medium
Operation and
maintenance
costs
High
Low
Very low
Low
Unknown
Management
Simple control
by pH,
Simple control by
conductivity and conductivity; nitrite
Constant control of
Oxygen transfer
Oxygen
dissolved
nitrogen
the process
control
transfer control
oxygen (DO)
concentration
monitoring
concentration
measurements
16
Assessment of a partial nitritation/Anammox system for nitrogen removal
Table 5. Matrix for the assessment of the sustainability of biological nitrogen removal systems
(1) suitability to treat ammonium-rich streams).
Partial
nitritation
(‘partial’
SHARON)
Anammox
CANON
OLAND
Resource
consumption
None
None
None
None
N2O, CO2
emissions
Possible
None
Possible
Possible
Process/factor
Conventional
nitrification/
denitrification
Suitability
1)
aspect
Potential
environmental
impact from
installation
Energy demand
Sludge
production
Area requirement
Reliability
Public
acceptance
Acceptance
among
researchers
Applicability at
local treatment
systems
Scale:
High
Medium
Low
Very low
Table 6. Cost estimation for separate supernatant treatment, after Fux (2003).
Factors decisive
for cost estimation
Investment
Operation
Energy
Maintenance
Control/staff
Chemicals
Sludge disposal
Total cost
Nitrification/denitrification
EUR per kg Nelim
1.35
0.35
0.70
0.30
0.50
-1
(0.2 EUR kgCH3OH )
0.30
3.50
17
Combined partial
nitritation/Anammox
EUR per kg Nelim
1.30
(60% NH4 to NO2)
0.15
0.70
0.30
0.05
-1
(0.2 EUR kgHCl )
Negligible
2.50
Luiza Gut
TRITA LWR LIC 2034
costs for denitrification are heavily dependent
on the biomass yield (estimated as 0.2 g
CODbiomass g-1 CODdosed) and the final electron
acceptor (nitrate for values in Table 6). The
overall costs estimated for the combined
partial nitritation/Anammox process are
almost 1.5 times lower than for the nitrification/denitrification alternative. A conventional extension of the activated sludge system consisting of introducing the nitrification
and providing an additional anaerobic volume for the denitrification amounts to 8.0
EUR per kg nitrogen removed, whereas the
overall costs estimated for a full-scale partial
nitritation/Anammox plant are 2.5 EUR kg-1
Nremoved. All the data is for 2003. Consequently, the separate treatment of the digester
supernatant is definitely more cost-effective
for the assumed size of plant than a conventional extension of the activated sludge process.
During a scale-up of the biofilm system, the
investment price of the biofilm carriers needs
to be taken into account. The market price of
Kaldnes rings is nowadays 3800 SEK m-3
(approx. 420 EUR m-3) (Mele, 2005). It imposes additional initial costs but the choice of
the option applied in the full scale should be
taken in a broader context, considering the
location and the size of the plant, energy
consumption for aeration, cost of energy in a
specific country, cost of mixing devices,
pumps, heating, maintenance costs, etc.
Kaldnes rings have been successfully applied
in a full-scale deammonification plant at
Hattingen WWTP, Germany and the solutions to the problems in the operation and
maintenance have been reported (Rosenwinkel et al., 2005). At the other full-scale
Anammox reactor in Rotterdam, the Netherlands, the initial problems with establishing
the granular Anammox sludge culture in an
up-flow reactor occurred (van Loosdrecht,
2004). Additionally, a study presented by
Wett (2005) gives an account on solving
scaling-up problems in a SBR full-scale
deammonification plant at the Strass WWTP,
Austria.
3.4. Applications of the Anammox
process
The implementation of the Anammox process in different systems is presented in Table
7. It can be noticed that the highest nitrogen
removal capacity was obtained in the gas-lift
reactor with granular sludge (Sliekers et al.,
2003) and amounted to 8.9 kg N m-3 d-1. This
was, however, shown only in a laboratoryscale pilot plant. Jetten et al. (1997) reported
a high maximum nitrogen removal capacity in
a fluidised-bed reactor as 2.6 kg N m-3 d-1.
Reactors with very efficient biomass retention need to be applied in order to mitigate
the slow biomass yield of the Anammox
bacteria. The above systems are especially
suitable, but also a sequencing batch reactor
(SBR) with the activated sludge has also been
studied frequently (Strous et al., 1998; Fux et
al. 2002; Fux, 2003). Dapena-Mora et al.
(2005) performed also experiments on upgrading the SBR reactors by placing inside an
internal hollow fibre membrane module or
zeolite carrier materials. Furthermore, Hassanzadeh (2005) suggests the combined use
of partial nitritation/Anammox and ion exchange or precipitation of magnesium ammonium phosphate.
Interestingly, van Dongen et al. (2001a) argues that biofilm (packed or moving-bed)
and granular sludge reactors are the most
appropriate alternative for the implementation of the Anammox process in full scale. In
both types of reactor configuration, the preseparation of the input suspended sludge is
recommended.
Moving-bed bioreactors with biofilm Kaldnes carriers were applied as well (Beier et al.,
1998; Hippen et al., 2001; Płaza et al., 2002;
Trela et al., 2004a, 2004b; Rosenwinkel and
Cornelius, 2005). Independent research centres obtained high specific nitrogen removal
rates oscillating around 2 g N m-2 d-1 (Beier et
al., 1998; Helmer et al., 2000; Hippen et al.,
2001; Seyfried et al., 2001; Szatkowska, 2004;
Cema et al., 2005a). The AnoxKaldnes group
(the AnoxKaldnes group web page) estimates
the specific effective biofilm surface as 500
m2 m-3 (Kaldnes rings are 9.1x7.2 mm). van
Dongen et al. (2001a) suggest that it is possible to decrease the reactor volumes with the
18
Assessment of a partial nitritation/Anammox system for nitrogen removal
Table 7. Summary of different nitrogen removal systems with the use of the Anammox
process (nd- no data).
System
type/scale
Influent
Synthetic
medium
Fixed-bed
reactor
(FBR)/labscale
References
Biofilm
FBR 1 PCV
2
3
250 m /m
0.08-0.42
3
kg N/m d
0.35
3
kg N/m d
nd
FBR 2 PCV
2
3
250 m /m
0.07-0.55
3
kg N/m d
0.38
3
kg N/m d
3.5
3
kg N/m d
FBR 3 PP
2
3
90 m /m
0.14-0.44
3
kg N/m d
nd
Sand/biofilm
1.0
3
kg N/m d
0.35
3
kg N/m d
1.8
3
kg N/m d
+
(0.8 kg NH4 3
N/m d)
Sludge
digestion
effluent
Sand/biofilm
1.2
3
kg N/m d
1.5
3
kg N/m d
+
(0.7 kg NH4 3
N/m d)
0.15
kg N/kg
VSS d
Synthetic
medium/
sludge liquor
Sand/biofilm
0.2 – 2.6
3
kg N/m d
5.1 kg N/m d
0.04 - 0.26
kg N/kg
SS d
Jetten et al.
(1997, 1998)
Sand/biofilm
nd
1.5
3
kg N/m d
+
(0.4 kg NH4 3
N/m d)
nd
Mulder et al.
(1995)
PVC disc/
biofilm
PVC disc/
biofilm
1.4 – 3.2
2
g N/m d
1.5 – 3.3
2
g N/m d
nd
0.4 – 1.2
2
g N/m d
nd
nd
Synthetic
medium
PVC disc/
biofilm
2.3 g N/m d
2
nd
1.55
2
g N/m d
Pynaert et al.
(2002)
Sludge
liquor
Sludge
liquor
Sludge
liquor
Sludge
liquor
Partial
nitritation
effluent/
sludge liquor
‘partial’
Sharon
effluent/
sludge liquor
Kaldnes
rings/ biofilm
Kaldnes
rings/ biofilm
Kaldnes
rings/ biofilm
Kaldnes
rings/ biofilm
2
nd
2
nd
2
nd
2.2
2
g N/m d
2.0
2
g N/m d
2.0
2
g N/m d
2.0
2
g N/m d
Hippen et al.
(2001)
Beier et al.
(1998)
Seyfried et
al. (2001)
Rosenwinkel
et al. (2005)
Synthetic
medium
(FBR 2
supplied
with effluent
from partial
nitritation)
Rotating
biological
contractor/fullscale
Rotating
biological
contractor/labscale
Leachate
SBR/pilotplant scale
Specific
reaction
rates
1.1
3
kg N/m d
Baker yeast
plant effluent
Moving-bed
system/ labscale
Maximum
nitrogen
removal
capacity
1.3
3
kg N/m d
Fluidised-bed
reactor/fullscale
Moving-bed
system/pilotscale
Nitrogen
loading rate
Glass beads/
biofilm
Synthetic
medium
Fluidised-bed
reactor/labscale
Support
material/
type of
biomass
Leachate
Partial
nitritation
effluent/
sludge liquor
nd
3
4.8 g N/m d
4.6 g N/m d
4-8 g N/m d
-1
0.18
kg N/kg
VSS d
Strous et al.
(1997)
Fux et al.
(2004)
Strous et al.
(1997)
Strous et al.
(1997)
Siegrist et al.
(1998)
Hippen et al.
(2001)
160 kg d
nd
Kaldnes
rings/ biofilm
0.5 – 2.3
2
g NH4-N/m
d
nd
0.6 – 2.3
g NH42
N/m d
Szatkowska
(2004)
Granular
sludge
1.2
3
kg N/m d
0.75
3
kg N/m d
0.18
kg N/kg
TSS d
van Dongen
et al. (2001b)
Activated
sludge
nd
2.4
3
kg N/m d
Activated
sludge
nd
0.8 – 0.9
3
kg N/m d
19
0.3
kg N/kg
TSS d
0.12 – 0.16
kg N/kg
TSS d
Fux et al.
(2002)
Fux et al.
(2003)
Luiza Gut
TRITA LWR LIC 2034
Table 7. Summary of different nitrogen removal systems with the use of the Anammox
process (nd- no data) (contd).
System
type/scale
SBR/labscale
Membraneassisted
bioreactor
Up-flow
reactor:
• Pilot-plant
Influent
Support
material/ type
of biomass
Synthetic
medium
Activated
sludge/
Activated
sludge+zeolite
carrier material
40-150
3
g N/m d
Synthetic
medium
Granular
sludge
Synthetic
medium
References
52-130
3
g N/m d
0.30-0.34
g N/gVSS d
DapenaMora et al.
(2005)
0.75
2
g N/m d
nd
0.65
kg N/kg TSS d
Activated
sludge in a
SBR reactor
nd
100
3
g N/m d
0.24
g N/gVSS d
Synthetic
medium
Activated
sludge
0.05-0.08
g NH4-N/
g MLSS d
nd
nd
Synthetic
medium
Granular
sludge
nd
2.9
3
kg N/m d
6.4
3
kg N/m d
nd
• Lab-scale
Gas-lift
reactor/labscale
UASB/labscale
Granular upflow reactor/
lab-scale
Bench-scale
upflow
biological
aerated filter
(BAF)
Maximum
nitrogen
removal
capacity
Specific
reaction rates
Nitrogen
loading rate
nd
DapenaMora et al.
(2004)
DapenaMora et al.
(2005)
SurmaczGórska et
al. (2003)
Imajo et al.
(2004)
nd
DapenaMora et al.
(2004)
Sliekers et
al. (2003)
Synthetic
medium
Granular
sludge
2.0
2
g N/m d
nd
1.15
kg N/kgTSS d
Synthetic
medium
Piggery
waste
Granular
sludge
10.7
3
kg N/m d
8.9
3
kg N/m d
nd
Granular
sludge
1.02
3
kg N/m d
0.7
3
kg N/m d
0.08
kg N/kgVSS d
Ahn et al.
(2004)
Effluent
from a
paper mill
factory
Granular
sludge
0.52
3
kg N/m d
0.14
3
kg NH4-N/m d
nd
Schmidt et
al. (2004)
Piggery
waste
Granular
sludge
1.36
3
kg N/m d
0.72 kg N/m d
0.09
kg N/kgVSS d
Hwang et
al. (2004)
Synthetic
medium
Granular lava
media
1.1
3
kg NH4-N/m
d
nd
nd
Wang et al.
(2004)
application of the granular sludge as the
specific surface of granules is 2000 m2 m-3.
High nitrogen elimination has also been
feasible in fixed-bed reactors (FBR) with the
polyvinyl chloride (PCV) carrier material
(Fux et al., 2004) or glass beads (Strous et al.,
1997). Other designs for Anammox reactors
take advantage of the nitrogen gas produced
during the process. A reactor analogous to a
UASB (upflow anaerobic sludge blanket)
reactor could be applied and nitrogen gas
could be used for mixing. Surmacz-Górska et
al. (2003) and Dapena-Mora et al. (2005)
3
presented the possibility of attaining the
Anammox process in membrane-assisted
bioreactors.
Systems for the Anammox process can be
used for the treatment of many types of high
strength ammonia wastewater among which
supernatant and leachate streams are the
most appropriate. Both media have a comparable composition so can be treated by the
same processes. A low value for the average
biodegradable COD/N ratio is characteristic
for the supernatant and leachate (leachate has
20
Assessment of a partial nitritation/Anammox system for nitrogen removal
Van Hulle, 2005). In the case of the
SHARON process, the insight gained by
simulations resulted in removing the pilot
plant tests and allowed a direct construction
of the process in the full-scale (Hellinga et al.,
1999; Mulder et al., 2001). The SHARON
process modifications to couple with the
Anammox process for treatment of ammonium-rich streams have also been modelled
(Volcke et al., 2002b; Van Hulle, 2005). What
is more, the continuously aerated ‘partial’
SHARON reactor was examined by establishing a reliable model and simulating the
behaviour of the process (Volcke et al.,
2002a, 2003). The influence of temperature
and pH parameters on obtaining the desired
nitrite-to-ammonium ratio in the effluent and
the prevention of toxic nitrite concentrations
was shown.
The partial nitritation process was also modelled in nitrifying membrane-assisted bioreactor (MBR) treating the digester supernatant
(Wyffels et al., 2004). The modelling of the
process start-up as well as the effects of
changes in the process parameters allowed
for further optimisations of the oxygenlimited partial nitritation process. It was
argued that the modelling could provide a
tool for scaling-up the process by performing
scenario the analyses during simulations.
A mathematical model to evaluate the influence of ammonium surface load (ASL) and
the temperature on a fully autotrophic nitrogen removal process in an aerated biofilm
CANON reactor was studied by Hao et al.
(2002a,b) and Hao and van Loosdrecht
(2004). The ASL was associated with the
biofilm thickness. Simulations with different
loading rates (0.25-4 g NH4-N m-2 d-1) were
run at a constant temperature of 20oC and a
fixed biofilm depth of 0.7 mm. It has been
proven that a thin biofilm has limited capacity for the activity of the Anammox process.
At a constant temperature and defined ASL,
there is always an optimal biofilm depth to
achieve the maximum ammonium nitrogen
removal efficiency. Alternatively, at a defined
biofilm depth a lower temperature requests a
lower ASL and a lower DO for a better nitrogen removal. Relatively high nitrogen
removal efficiency along with the variable
only a periodically increased COD content),
which
makes
traditional
nitrification/denitrification treatment inapplicable or
too expensive. Rotating Biological Contractor
(RBC) systems with a biofilm bacterial
growth have been mainly used for treatment
of landfill leachates in the deammonification
process (Hippen et al., 2001). As for the
supernatant, new biological methods have
recently been put in deployment. Among
these, the applications of the Anammox
process are the most promising for the future. In the supernatant treatment, the investigated systems were both for the activated
sludge growth, e.g. in the SBR reactor (Fux,
2003) and for the biofilm development, e.g.
in a Moving Bed™ Biofilm Reactor (Beier et
al., 1998; Płaza et al., 2003a,b; Szatkowska,
2004).
3.5. Modelling of the systems with
biological wastewater treatment
The modelling, optimisation and simulation
of biological nitrogen removal processes has
been the subject of many publications (Finnson, 1994; Jeppsson, 1996; Gujer et al., 1999;
Ekman, 2005; Samuelsson, 2005; Van Hulle,
2005). An array of tests for the determination
of stoichiometric and kinetic parameters for
the microbial conversions (model calibration)
is a necessity in constructing models for a
full-scale process design (Henze et al., 1987).
A reliable and validated model is a tool for
simulating the different configurations of a
biological system. Modelling tools can be
used at different stages in the process development. They can be applied in advance of
implementing a process in the full scale as
well as can contribute to the optimisation
strategy of an existing system. To give an
example, Finnson (1994) investigated the
usefulness of a computer simulation model at
a full-scale activated sludge biological WWTP
in Sweden. There were also studies using
models to describe the biological processes in
biofilms (Koch et al., 2000; Kreft et al.,
2001).
In research concerning the novel processes
of nitrogen removal from wastewater, the
modelling tools were applied for the process
design and simulation (Van Hulle et al., 2003;
21
Luiza Gut
TRITA LWR LIC 2034
ASL can be achieved in practice by controlling the dissolved oxygen concentration exactly on the requirement of the momentary
ammonium load. On the other hand, at the
defined ammonium surface load, a lower
temperature needs a thicker biofilm and
hence a higher DO concentration to maintain
the nitrogen removal efficiency at a high
level. Therefore, for the full-scale application,
a careful control of the dissolved oxygen
concentration in the bulk liquid along with a
variable ASL in biofilm systems is obligatory
to achieve high nitrogen removal efficiency.
A separate issue concerning modelling of the
biological process is the area of a multivariate
data analysis (MVDA). So-called projection
methods (Eriksson et al., 2001) were studied
extensively with the purpose of modelling the
wastewater treatment systems. In the case of
the biological processes, the MVDA approach is relevant due to the existence of the
correlated variable groups and the necessity
of understanding the covariations between
them. Mossakowska (1994), van Dongen and
Geuens (1998), Hallin (1998), Tomita et al.
(2002), Miettinen et al. (2004) and MacGregor et al. (2005) studied the multivariate
monitoring and the analysis and control of
biological wastewater treatment processes.
Aguado et al. (2005) presents a study of the
MVDA methodology for detecting operational shifts in an SBR process. In the applied
technology, the multivariate monitoring of
variables describing large and correlated time
series provide an insight into the historical
data as well as the prediction of the effluent
quality in terms of changing the design or the
operational scheme.
4.1. Pilot plant description
The technical-scale pilot plant was constructed by the PURAC Company and is
located at the Himmerfjärden WWTP
(SYVAB AB), southwest of Stockholm by
the Himmerfjärden bay. It was continuously
fed with a supernatant from the dewatering
of a digested supernatant. A detailed description of the sludge handling at the Himmerfjärden WWTP can be found in Harabasz
(2004). The system that was preceded by a
buffer tank (0.8 m3) consisted of two reactors
in series (2.1 m3 each), followed by settling
tanks (0.125 m3 each). The pilot plant was
designed as a Moving Bed™ Biofilm Reactor
(MBBR) and filled up to 45-50% with Kaldnes® carriers (AnoxKaldnes Company, the
AnoxKaldnes group web page). The first
reactor (R1) was operated to obtain a partial
nitritation process whereas in the second one
(R2) an Anammox process was established.
The system was therefore named the twostep partial nitritation/Anammox. Both reactors were divided into three zones equipped
with a mechanical vertical mixer (two-blade
propeller) and a blower that was used only in
R1. The first zone of each reactor had a
heater installed. The pH correction in zone 1
of R2 could be done continuously with the
use of an on-line pH-electrode and was applied at the beginning of the experiments.
The pilot plant was built inside of a purposely-furnished container fully equipped
with manual and on-line instruments such as
a pH-meter, a dissolved oxygen meter, a
conductivity meter, and a thermometer to
control the process and collect the data.
The minimum efficient surface of the biofilm
on Kaldnes rings (K1) was estimated as 500
m2 m-3 in the bulk liquid. Therefore, the
filling rate results in an average 500 m2 of an
active biofilm surface in each reactor. The
Kaldnes biofilm carrier elements K1 are
made from polyethylene (PEHD). The material has a specific weight of about 0.95 kg l-1,
thus it floats in water. The density of the
biofilm carrier elements in bulk is 160 kg m-3.
The biofilm carrier elements are formed as
tubes with an internal cross, and with 18
external fins with nominal diameter of 9.1
mm and a nominal length of 7.2 mm
4. M ETHODOLOGY
The deammonification system for nitrogen
removal has been investigated at the technical-scale pilot plant at the Himmerfjärden
WWTP, Grödinge, Sweden. In this section, a
summary of the studies performed, the used
materials and the experimental procedures
will be presented. Further details are given in
Papers I-IV. An extended description of the
modelling tool used in Paper IV is included
in this chapter. The chapter also includes a
typical batch test procedure.
22
Assessment of a partial nitritation/Anammox system for nitrogen removal
(AnoxKaldnes Company, the AnoxKaldnes
group web page).
periods (Paper III). Stepwise decreases of the
dilution rate of the influent flow to the
Anammox reactor (Figure 3) and changes in
the hydraulic retention time (Table 8) were
the strategy aimed at varying loadings. The
internal recirculation was introduced with the
goal of substituting cold tap water used for
the dilution of the influent to R2 with the
effluent from R2. This strategy was discarded
due to the temporal Anammox process inhibition in March 2005. It was assumed that
toxic metabolites were accumulating in R2.
Another strategy was implemented in April
2005. It consisted of the external recirculation of the system effluent to the first zone
of R1 and simultaneous switching-off the
aeration in that zone. The aim of this strategy
4.2.
System
configurations
and
operational approach
Figures 1 and 2 show the technical-scale pilot
plant configurations and operational changes.
The pilot plant was operated at subsequent
aerobic and anaerobic conditions to obtain
the two-step process. The reactors were
initially operated separately for 1 year to
develop nitrifying and Anammox culture in
reactors 1 and 2, respectively (Horeglad,
2001; La Rocca, 2001). When the reactors
were connected, the influent load to the
Anammox reactor was increased during the
June – August 2003 and February – July 2004
Conductivity
Conductivity
pH, T
DO
Settling
tank (buffer)
Settling
tank
Conductivity
Settling
tank
pH, T
Effluent
R1
Air
Deoxidising
Dilution with tap water
column
R2
Internal recirculation
External recirculation
Fig. 1 Pilot plant configurations; R1-partial nitritation reactor, R2-Anammox reactor
(based on Trela et al., 2004d, 2005).
Average temperature
Changes in
parameters
around 35oC
around 30oC
pH correction in R2
No aeration in R1 z1
External
Internal
Recirculation
Dilution of
R2 influent
System
description
2004
2003
2005
Fig. 2 Operational strategies for the partial nitritation/Anammox system over the period
May 2003 – April 2005 (based on Trela et al., 2004d, 2005).
23
22-Apr
20-Jan
22-Feb
22-March
7-Apr
21-Oct
11-Nov
10-Sep
4-May
5-Sep
11-Aug
1-May
Two-step partial nitritation/Anammox system
Luiza Gut
TRITA LWR LIC 2034
5
1.5
Influent load
g N m -2 d-1
1.0
average dilution factor
3
2
0.5
dilution factor
4
dilution factor
1
05
20
-A
pr
-
30
-J
an
-0
5
ov
-0
4
11
-N
23
-A
ug
-0
4
4Ju
n04
04
16
-M
ar
-
ec
-0
3
27
-D
8O
ct
-0
3
0
20
-J
ul
-0
3
1M
ay
-0
3
0.0
date
Fig. 3 Anammox reactor – influent nitrogen load and the dilution factor (based on Trela et al.,
2004d, 2005).
was to denitrify the nitrate nitrogen generated
in the Anammox process.
Additionally, in 2005 the temperature in the
system was gradually decreased from 35oC to
30oC (Figure 2) down to 27oC on average.
Furthermore, the pH correction in the
Anammox reactor was stopped in May 2004.
This strategy resulted in savings of the
chemicals without negative impacts on the
process performance.
The two-step process was operated steadily
for 2 years (Paper I, III, IV). A substantial
nitrogen removal observed in R1 in May
2005 directed the research towards investigating the reaction rates in R1 whilst maintaining the Anammox culture in R2.
4.3. Measurements and analytical
procedures
Table 9 shows a summary of the methods
used in this study. The results from measurements, analyses and the derived variables
presented in Table 10 were used in the papers
appended. The grab samples taken from
different points of the pilot plant were immediately filtrated with a 25-mm prefilter and
a 0.45-μm filter and analysed. The equipment
for the performance of measurements and
analyses is shown in Table 11. The Sludge
Volume Index (SVI) was determined after 30
minutes of sludge settling by measuring the
volume occupied by the sludge.
Table 8. Hydraulic retention time in the
pilot plant operated in different configurations in the period 2003-2005.
Date
Average HRT (d)
R1
R2
28 Apr – 31 Jun 2003
2
3
1 July – 25 Jul 2003
1
3
26 Jul –29 Sep 2003
1
2
30 Sep - 17 Oct 2003
2
2
18 Oct 2003 – 31 April
2005
2
3
Table 9. Summary of the methods and tools used in Papers I-IV and chapter 5 of the thesis.
Method/tool
Oxygen Uptake Rate (OUR) tests
Batch tests
Univariate data analysis
Multivariate data analysis
Pilot-plant operation
Two-step system
Papers:
I
X
II
X
III
IV
X
X
X
X
X
Chapter 5
X
X
X
X
X
X
X
X
X
24
Assessment of a partial nitritation/Anammox system for nitrogen removal
Table 10. Overview of the measurement and analyses performed during pilot plant operation.
Influent
characteristics
Reactor 1 (R1)
Zone 1, 2, 3 and out
Reactor 2 (R2)
Influent, zone 1, 2, 3
and out
Measurements
(Weekdays)
pH, conductivity,
temperature
pH, conductivity;
only in zones:
temperature,
dissolved oxygen
(DO)
pH, conductivity;
only in zones:
temperature, DO
Analyses
(Different time spans)
NH4-N, alkalinity, COD, PO4-P, SS
(total suspended solids), VSS
(volatile suspended solids)
NH4-N, NO2-N, NO3-N, alkalinity,
COD, PO4-P, organic acids,
profiles of Ninorg forms, SS, VSS,
SVI (Sludge Volume Index)
Derived variables
(Different time spans)
Flow rate (Weekdays),
Load
Flow rate (Weekdays),
HRT, Load, NH3,
HNO2; NO2-N/NH4-N
ratio
NH4-N, NO2-N, NO3-N, alkalinity,
COD, PO4-P, organic acids,
profiles of Ninorg forms, SS, VSS,
SVI
Flow rate, dilution rate,
HRT, Load, HNO2
concentration,
NO2-N/NH4-N ratio
Table 11. Equipment for measurements and analyses performance (N/A – not adequate).
Parameter
Manual equipment
Analytical devices
Conductivity meter:
HACH44600
On-line equipment
Analon pH 10,
Contronic (HACHLange AB)
Analon pH 10,
Contronic (HACHLange AB)
Dr Lange Analon Cond
10
pH
pH meter model WTW
pH330
Temperature
Thermometer Hanna
model HI9063
Conductivity
Dissolved oxygen
(DO)
Oxygen meter YSI52CE
Cerlic BB2 - O2X
N/A
NH4-N, NO2-N,
NO3-N, alkalinity,
COD, PO4-P, organic
acids
N/A
N/A
Suspended Solids
(SS) and Volatile
Suspended Solids
(VSS); Sludge
Volume Index (SVI)
Cylinder and stopper
(SVI)
N/A
N/A
N/A
N/A
TECATOR-AQUATEC
5400 Analyser, DrLange
VIS Spectrophotometer
XION 500,
spectrophotometer
HACH model DR/2010
(only COD)
Vacuum filtration
apparatus connected
with a plate supporting
the glass fibre (SS,
VSS)
keep the temperature as in the pilot plant.
The covered test vessels were equipped with
magnetic slow-stirring implements. Measurements of pH value, DO concentration
and conductivity were performed and samples were taken. The test lasted 8 hours on
average with hourly sampling patterns.
4.4. Batch tests
To follow the reaction rates in the pilot-plant
reactors some batch tests were performed.
The test execution methodology was developed by Gut (2003) and extended by Gut and
Płaza (2003), Szatkowska et al. (2003a,b;
2004a), Szatkowska (2004), Siembida (2004),
Cema et al. (2005a,b) and Mele (2005).
Each batch test was run in a 1-litre bottle
50%-full with Kaldnes rings with the biofilm
biomass and poured over with the supernatant from R2. On test days, the biomass
was taken from the Anammox reactor of the
continuously working pilot plant, put into
batch vessels and placed in a water bath to
4.5. Oxygen Uptake Rate (OUR) tests
A methodology to execute an Oxygen Uptake Rate (OUR) test for biofilm bacterial
cultures on Kaldnes has been developed
(Paper I). The method included a modified
procedure of the OUR tests for activated
sludge proposed by Surmacz-Górska et al.
(1996). Measurements of the dissolved oxy25
Luiza Gut
TRITA LWR LIC 2034
observations. The PCA modelling has been
extended by finding covariations in two
blocks of data, denoted as X and Y with the
aim of predicting Y from X for new observations (Wold et al., 2001). This method is
called the Partial Least Squares projections to
latent structures (PLS) and can be treated as a
regression modelling tool for assessing how
the factors in the X block influence the responses in Y, finding collineation and adjusting factors to get the desired profile for the
responses. The nomenclature used for the
PCA and PLS modelling approach together
with the geometric representation of the
methods is presented in Paper IV.
The PCA method has been used in Paper IV
to show how the observations are related and
hence find any group of observations that
deviate or form separate classes. In the PCA
approach, a line (or a component) is fitted in
the direction of the greatest variability of the
measured variable space. Then, the second
line is approximated in the next greatest
direction of the variability orthogonal to the
first component; hence, a plane is obtained.
If necessary, the subsequent lines orthogonal
to the plane are found. During this process
the goodness of prediction is simultaneously
computed by a cross-validation method. This
is repeated until no systematic variability
remains. A trade-off between the explained
and predicted variation determines the number of components. For details refer to Eriksson et al. (2001).
The most important difference between the
PCA and PLS methods is that PCA describes
the maximum variance in a least square projection of X, whereas PLS is a maximum covariance model of the relationship between X and
Y (Eriksson et al., 2001). The importance of
a given X-variable for Y, where Y can be a
single variable or a block of variables, is
computed as PLS regression coefficients
(bmk). This expresses the relation between the
Y variables and all the terms in the model.
The measure of a variable importance is
identified by the large absolute values in the
PLS regression coefficients. If a variable is
important for the modelling of X (large loadings, pka), a variable importance for the projection (VIP) function should be used. The
gen concentration during its uptake by the
biofilm bacterial culture and during the subsequent addition of selective inhibitors of the
nitrifying bacterial populations were carried
out. The sodium chlorate (NaClO3) inhibited
the nitrite oxidation by Nitrobacter species
whereas allylthiourea (ATU) inhibited the
nitritation process. The respiratory activity of
the heterotrophs was also calculated as the
remaining oxygen uptake after the addition of
a dose of the ATU. This method, however,
does not allow for distinguishing between the
oxygen consumption for the substrate oxidation and the endogenous respiration. For a
more detailed description refer to Długołęcka (2004).
An emphasis has been put on preparing the
equipment for the OUR test, adjusting the
optimal conditions during the test runs, selecting the optimal amount of Kaldnes carriers and checking the inhibitory concentrations of NaClO3 and ATU (Paper I). Second,
the nitrifying activity has been assessed in the
partial nitritation reactor (Papers I and II)
and in the Anammox reactor (Paper II). The
proposed test procedure was successfully
verified (Paper I and II). The inhibiting effect
with 100 Kaldnes carriers has been achieved.
17 mmol l-1 as a final concentration of NaClO3 solution and 43 μmol l-1 as a final concentration of ATU solution were injected
into the bottle when the dissolved oxygen
level was at 4 and 2-3 mg O2 l-1, respectively.
Papers I and II present comprehensive descriptions of the test procedures.
4.6. Modelling of the process data with
the SIMCA-P software
The multivariate data analysis (MVDA) is
designed to extract information from a data
set with the purpose of interpreting covariances and patterns in the variables. An overview of the multivariate character of the data
can be obtained by the Principal Component
Analysis (PCA) method (Wold et al., 1987).
This method can discern deviations in the
data set and gain an understanding of the
relationship between variables. The PCA
method can also reveal groupings amongst
variables. The groups can be used as the
established class models for classifying new
26
Assessment of a partial nitritation/Anammox system for nitrogen removal
VIP summarizes the importance of an Xvariable for both variable data blocks X and
Y. After the inspection of the regression
coefficients and VIP plots, it can be decided
to exclude unimportant variables.
In the Paper IV, the SIMCA-P package was
used to perform the MVDA (Umetrics AB,
Umetrics AB web page). All variables were
pre-processed using the mean centring and
auto scaling to unit variance. The scaling
function gives variables equal influence in the
model. It is necessary that variables are not
expressed in different units and display substantially different numerical ranges. In this
study, the data were both mean centred and
scaled to unit variance (autoscaled). Additionally, the data excluded from the model
form the residuals matrix and are of diagnostic interest (Wold et al., 2001). A Distance to
Model in X-space (DModX) value is used to
inspect the model residuals and enables to
detect outliers in the X-space, i.e. process
points that deviate from the stable operation
of the process. In case of the PLS-regression
modelling, the residuals of a Y-block should
form a straight line in a normal probability
plot. If a curvature is detected, the plot may
be improved by transforming parts of the
data, e.g. by using a logarithmic function. A
normal distribution of the data for a single
variable is the goal in the transformation
procedure.
The validation of an output model is done by
means of cross-validation (CV), response
permutation testing for checking the statistical significance of the prediction in case of
PLS modelling. An external validation can be
also applied and consists of using a test data
set that is obtained through the use of the
multivariate design. The CV method for
validation is commonly used in the SIMCA-P
software and is applicable in both PCA and
PLS approaches. Dividing the data into a
number of groups, usually from five to nine,
and developing a number of parallel models
for each of the group deleted perform the
CV validation.
5. R ESULTS
AND DISCUSSIONS
5.1. Bacterial identification and activity
5.1.1. FISH tests
The Fluorescence In Situ Hybridisation
(FISH) is a technique that can be used to
detect specific groups of microorganisms. It
uses fluorescent probes that only bind selectively to the 16 S rRNA. As a result of using
probes for particular bacteria, it is possible to
detect individual cells of a specific type of
microorganisms. The FISH method is a
useful tool in molecular ecology. Individual
bacteria of targeted species are detected microscopically, located and quantified in the
B. Anammox reactor;
Anammox: AMX-820/CY3, pink
Eubacterial probe: CY5, purple
A. Partial nitritation reactor;
Nitrifiers: NSE-1472, fluos, green
Eubacterial probe: CY5, purple
Anammox: AMX-820/CY3, pink
Fig. 4 Results from FISH analyses (photos Wouter van der Star).
27
Luiza Gut
TRITA LWR LIC 2034
background of a complex population.
By courtesy of the research group from the
Delft University of Technology, Kluyver
Laboratory for Biotechnology, the Netherlands, the FISH technique was applied to the
samples taken from both reactors of the pilot
plant in June 2004. Figure 4 shows the results
from the FISH analyses. Only the biofilm
bacteria were the subjects to the analyses; the
formamide concentration was 35% at the
hybridisation temperature 47oC.
The partial nitritation reactor was tested for
the presence of nitrifiers. The sample from
the biofilm mainly hybridises with the NSE1472 probe, Figure 4A. This probe is very
specific for Nitrosomonas europeae, Nitrosomonas
eutropha and Nitrosomonas halophila, meaning
that one of these three organisms is dominant in the nitrifying population. It was analysed that there are some Anammox bacteria
present also in the partial nitritation reactor.
It has been proved that the population in the
Anammox reactor indeed contained Anammox bacteria. The AMX-820 probe hybridises both with Brocadia anammoxidans and
Kuenenia stuttgartiensis (Figure 4B). Therefore,
it was not determined during these investigations which of these Anammox species are
present. The Anammox population was
roughly estimated as 20-30% of the whole
bacterial community in the Anammox reactor.
Later tests performed in June 2005 by a research group of the Gothenburg University,
Department of Chemistry, Sweden (Hulth,
2005) confirmed that Brocadia anammoxidans is
present in the Anammox reactor. The BAN162 probe was used to assert the presence of
this bacteria strain.
(1996). Daily aeration of the media in the
initial tests resulted in achieving the predominance of nitrite oxidation over the ammonia oxidation. The enhanced Nitrobacter
activity was therefore induced by the aeration
procedure before the test. Such behaviour of
the bacterial population did not however
occur in the partial nitritation reactor as the
nitrite oxidation was suppressed (Paper I, II,
III). The shortened aeration showed the
prevailing Nitrosomonas group activity in all
the zones of R1 with the zone 1 being the
most active. In Paper I, the most adequate
ammonia concentration for oxidation of
ammonia only to nitrite was calculated in that
zone.
The successful development of the OUR
methodology enabled to check the presence
of nitrifiers in the Anammox reactor and
compare the nitrifying activity results between reactors in Paper II. The nitrifying
activity in R1 was related to the biofilm on
the Kaldnes rings (Paper I and II), whereas in
R2 the presence of nitrifiers was proved to
predominantly exist in the activated sludge
(Paper II). Occurrence of the Nitrosomonas
community in the activated sludge of the
Anammox reactor is advantageous due to its
contribution in supplying nitrite for the
Anammox culture in the biofilm and sustaining oxygen-limited conditions (Paper II). The
main findings show that Nitrosomonas species
are more active than Nitrobacter bacteria in
both reactors of the pilot plant. The nitrifying
activity in the Anammox reactor should not,
however, be overestimated. The activities in
R1 are on average 20 times higher when
compared with the biofilm culture and 10
times higher in the activated sludge from R1
(Paper II). Irrespective of the order of magnitude, the Nitrosomonas activity was 2.5 times
higher than the Nitrobacter activity, measured
as OUR in both reactors.
The monitoring potential of the OUR tests
to reflect the changes in the activity profile of
the nitrifying bacterial culture in R1 was
shown in Paper I. Paper II demonstrated also
the applicability of the OUR tests to detect
changes in the nitrification activity over time.
A variable nitrifying activity was expected as
the result of changes in the moving-bed
5.1.2. Application of OUR tests
Paper I focused on establishing a reliable
monitoring tool for the assessment of the
nitrifying activity in the biofilm partial nitritation reactor. It was demonstrated that 100
Kaldnes carriers are an optimal number for
achieving reliable results. Separate tests verified that the 17 mmol l-1 final concentration
of NaClO3 was adequate. The ATU final
concentration was kept at 43 μmol l-1, as
recommended by Surmacz-Górska et al.
28
Assessment of a partial nitritation/Anammox system for nitrogen removal
system configuration. Nitrifying activity in
the activated sludge of the Anammox reactor
showed an increasing tendency but it was low
in comparison with activities in R1 over one
year.
Surmacz-Górska et al. (2003) also applied the
OUR tests to measure the respiratory activity
of the nitrifying activated sludge present in
the membrane-assisted bioreactor with the
Anammox process during its start-up. It was
found that after the introduction of the
Anammox process, the ammonia- and nitriteoxidizing bacteria increased their activity. It
was suspected that the Nitrosomonas-like bacteria could find more suitable conditions in a
mixed biocoenosis or changed their metabolism to be able to denitrify under anoxic
conditions. The enhancement of the Nitrobacter-like bacteria activity can be explained by
the high persistence of these bacteria in the
activated system. Moreover, it was deduced
that other groups of bacteria can have the
same vulnerability to sodium chlorate and for
this reason the activity results could be overvalued with regards to the activity in the
reactor. It however gives some insight into
the high nitrite-oxidizing bacteria activity
presented in Paper I.
eration of the two-step partial nitritation/Anammox system.
The stoichiometrical demand of supplying
the Anammox reactor with a proper influent
directs the reliability of efficient nitrogen
removal towards the stable operation of the
partial nitritation reactor (Papers III, IV).
Formation of nitrite at the suitable rate with
ammonium (a nitrite-to-ammonium ratio
about 1.3) is a result of the interplay between
influent ammonium nitrogen concentration,
DO concentration in the bulk liquid and
adequate pH drop for a given reactor configuration (Papers I, III, IV). Conductivity
measurements are highly applicable for monitoring of both processes (Papers III, IV). In
case of R1, the oxidation of ammonium and
consumption of alkalinity are parallel to the
conductivity decrease, whereas in R2 the
transformation of formed ions into molecules results in a conductivity decrease at a
stable rate. During the operation of the fully
mixed Anammox reactor, monitoring of the
effluent nitrite nitrogen concentration is
obligatory (Paper III, IV) as it is an inhibitory
compound for the Anammox culture. The
results of the univariate data analysis presented in Paper III were confirmed in Paper
IV by applying the multivariate approach to
the same data set. The optimisation strategy
of shortening the HRT, introducing internal
and external recirculation as well as changes
5.2. Factors affecting system efficiency
Table 12 shows the factors that were recognized as the most significant for proper op-
Table 12. Recognition of factors affecting the deammonification system performance.
Process
Partial
nitritation
Anammox
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Factors
Supernatant characteristics
Oxygen supply to nitritation reactor
Effluent nitrite-to-ammonium ratio
pH decrease and alkalinity consumption
Hydraulic retention time
Temperature
Free ammonia and free nitrous acid concentrations
The influent nitrogen load
Oxygen-limited conditions
Nitrite-to-ammonium ratio in the influent
pH increase
Nitrite nitrogen concentration in the reactor
Activity of the Anammox bacterial culture (reaction rates)
Hydraulic retention time
Temperature
29
Paper
I, III, IV
III, IV
Luiza Gut
TRITA LWR LIC 2034
IV repeatedly confirmed the stability of the
pH parameter in the influent. It did not
greatly influence the models describing both
the start-up period and the stable operation
of the partial nitritation/Anammox system.
The average alkalinity/NH4-N ratio was 1.1
(Paper I) and 1.6 (Paper III) for the described
periods, respectively, confirms the excess of
alkalinity in the digester supernatant to obtain
a stable oxidation of half of the ammonium
to nitrite. An average alkalinity/NH4-N ratio
for the experimental period presented in this
thesis is 1.4. Fux (2003) reported an alkalinity/NH4-N ratio of 1.2 in the digester supernatant, which is consistent with the results
presented in Paper I. The mean COD/N
ratio in the influent supernatant for the
whole period amounted to 0.5, which proved
that
the
traditional
nitrification
/denitrification treatment is inapplicable for
the supernatant stream. The temperature
range was 19-26oC and depended on seasonal
changes. The organic acids concentration
in the temperature in the system was successful. It allowed for assessing the different twostep system configurations.
5.2.1. Supernatant characteristics
The characteristics of the influent supernatant are presented in Papers I and III.
Comparing the results from these papers, the
average ammonium nitrogen concentration
was over 600 and 700 mg l-1, respectively and
for the whole period described it varied in
between 270 and 920 mg l-1. The ammonium
nitrogen variability occurs at the same time as
the changes in the alkalinity, which was also
confirmed in studies by Szatkowska et al.
(2005). Variability of the influent ammonium
nitrogen concentration determines to a high
extent the nitrite-to-ammonium ratio (Figure
5). Based on the results presented in Paper
IV (Trial 1) the relationship takes into account the effect of a pH drop and demonstrates a necessity of coping with the variable
concentration of the ammonium nitrogen.
Moreover, the modelling results from Paper
Fig. 5 Relationship between the influent ammonium nitrogen concentration, effluent (out)
pH value and nitrite-to-ammonium ratio (NAR) in the partial nitritation reactor.
30
Assessment of a partial nitritation/Anammox system for nitrogen removal
fluctuated in the supernatant and for the
whole period described was equal to 61 mg l1
. This value suggests that the digesters were
periodically overloaded with the biological
sludge. The sludge generation pattern at the
Himmerfjärden WWTP, the fermentation
efficiency and operation of the sludge dewatering units affect the quality and quantity of
the supernatant.
Conductivity changes at the inflow reflected
the variability of the influent ammonium
concentration, which is presented in Paper
III and IV, and confirmed in the studies by
Szatkowska et al. (2004b, 2005). Moreover,
Fux (2003) reported that conductivity measurements could be used to follow the nitrogen concentration in an SBR cycle.
The analyses of the total suspended solids
(SS) and volatile suspended solids (VSS) were
introduced to control the supernatant quality.
The average values at the influent to the pilot
for the period described in Paper I were 173
mg SS l-1 and 145 mg VSS l-1 whereas for the
whole evaluated period the average values
were very similar (178 mg SS l-1 and 152 mg
VSS l-1). Additionally, there were periodical
discharges of a large quantity of sludge from
the centrifuges that resulted in disturbances
in the operation of the pilot plant. The concentration of the suspended solids in the
influent was varying in the range 100-5000
mg SS l-1 and the discharge of solids was
removed in the buffer tank.
5.2.2. Partial nitritation process
Figure 6 presents conversions of the inorganic nitrogen forms in the partial nitritation
reactor. The partial nitritation reactor was
operated as a preceding step to remove nitrogen in the Anammox reactor. Other authors
(van Dongen 2001a; Volcke et al., 2003; Fux,
2004) argue also that a stable partial nitritation is an essential prerequisite for the
Anammox process. The initial underproduction of nitrite to supply to the Anammox
reactor in the start-up period was exchanged
in 2004 with a stable oxidation of more than
half of ammonia to nitrite (NAR=1.2 as
average value for the 2004) (Paper III). Until
March 2005, NO3-N concentration at the
effluent was on average 16 mg l-1, which
confirms stability of the process. An increase
of the nitrate nitrogen concentration in the
end of the described period was caused by
the external recirculation of the system effluent. Occasional losses of nitrogen were calculated through the whole experimental period
(Paper I, II, III). Examples of routine profiles
of inorganic nitrogen forms presented in
Paper I and II demonstrated that the most
robust nitritation occurred in zone 1 and 2 of
the reactor.
Seeding with the Anammox in the end of the
described period and no aeration in zone 1
1000
NH4-N in
N inorg out
NH4-N out
NO2-N out
NO3-N out
900
mg N l -1
800
700
600
500
400
300
200
100
1M
ay
1- -03
Ju
n
1- -03
Ju
1- l -0
Au 3
g
1- -03
Se
p
1- -03
O
c
1- t-03
N
o
1- v-0
D 3
ec
1- -03
Ja
n
1- -04
Fe
1- b-0
M 4
a
1- r-04
Ap
1- r-04
M
ay
1- -04
Ju
n
1- -04
Ju
1- l -0
Au 4
g
1- -04
Se
p
1- -04
O
c
1- t-04
N
o
1- v-0
D 4
ec
1- -04
Ja
n
1- -05
Fe
1- b-0
M 5
a
1- r-05
Ap
r05
0
date
Fig. 6 Variations of nitrogen forms in the partial nitritation reactor (based on Trela et al., 2004d,
2005).
31
Luiza Gut
TRITA LWR LIC 2034
resulted in high nitrogen removal and
changes in the distribution of the nitrifying
activity in the system (Paper II). As a result
of changes, a substantial nitrogen removal in
R1 was obtained in the period May-August
2005 in oxygen-limited conditions as well in
aerobic conditions. This phenomenon is now
subjected to further investigations. Rosenwinkel et al. (2005) described a similar trend.
Unscheduled deammonification in the nitritation reactor occurred at the full-scale deammonification plant at the Hattingen WWTP,
Germany. As a consequence, the operation
was changed into intermittent aeration to
attain subsequent aerobic and anoxic periods
for nitritation and Anammox, respectively,
occurring in one reactor.
The mean concentration of SS in R1 for the
whole period was equal to 294 mg l-1 with
85% of the organic part. The accumulation of
the solid particles might have been due to
hydraulic conditions in the reactor and occasional discharges of scum from centrifuges.
The sludge volume index of the sludge generated in reactor 1 was checked to amount on
average to 82 ml g-1, which indicates quite
good settling properties.
Effluent nitrite-to-ammonium ratio (NAR) ratio
The importance of stable operation of the
partial nitritation reactor with regard to the
NAR influence on the nitrogen removal in
the following step was emphasised in Papers
I, III and IV. The results showed that the
variability of the influent ammonium concentration could be coped with by adjusting the
oxygen supply. On this basis, the aeration
rate influences the pH drop. The drop of the
pH value by the unit of 1.5 conditions the
NAR equal to 1.3. Paper I and III describe
successful operation of the reactor with regard to obtaining the NAR oscillating around
1.3.
pH parameter
A typical drop of the pH value during the
nitritation process through using up the
alkalinity and carbon dioxide stripping was
confirmed in Paper I, III and IV. It appeared
to be applicable to monitor the partial oxidation of ammonia to nitrite in the first reactor
of the pilot plant and was included in the
control-monitor system for the partial nitritation/Anammox system given by Szatkowska
et al. (2005). The drop of pH value by the
unit of 1.5 is sufficient to obtain the nitriteto-ammonium ratio at the effluent around
the required value of 1.3. The logarithmic
correlation is characteristic for the pH parameter as the hydrogen ions are still produced when the buffering capacity is nearly
depleted. Values lower than the pH value of
6 are not expected due to natural inhibition
by free ammonia and free nitrous acid (Paper
I). The results described by Fux (2003) concerning the drop of the pH value buffered by
the alkalinity present in the supernatant to
obtain the NAR of 1.3 was comparable with
results presented in Paper I and III.
Dissolved oxygen (DO) concentration
The stratification of the dissolved oxygen
(DO) concentration in the partial nitritation
reactor showed in Paper I was part of the
strategy for achieving the washout of the
nitrite-oxidising bacteria. The DO value in
zone 1 was in the range 1.0-1.5 mg O2 l-1
whereas in zones 2 and 3 (periodically connected) in the range of 0.5-1.0 mg O2 l-1. The
supply of oxygen to the partial nitritation
reactor regulated the adequate pH drop (Paper I, III) and the value of 1 mg O2 l-1 was
found as satisfactory for a suitable pH regulation effect. Due to manual regulation of the
air supply, nitrate nitrogen concentration
sporadically appeared in the effluent. The online DO electrode installed in September
2004 resulted in more accurate DO adjustment in the range 0.6-1.5 mg O2 l-1 depending
on the operation strategy. In April 2005 the
aeration in zone 1 was temporarily switched
off in order to attain anoxic conditions for
denitrification when the recirculation of the
effluent to that zone was introduced.
Hydraulic Retention Time (HRT)
In the partial nitritation reactor, the HRT
fluctuated from 1 to 2 days and was changed
in order to vary the influent load. The decrease of the HRT to 1 day did not substantially affect the system efficiency. However,
during that time (July-September 2003) the
average NAR was 0.8, which was caused by
the underproduction of nitrite.
32
Assessment of a partial nitritation/Anammox system for nitrogen removal
HNO2 l-1 in zone 2 and 3 of R1 that can be
an additional inhibiting effect on further
ammonia oxidation and suppression of nitrite
oxidation. In Paper II, the correlation between the activity of ammonia-oxidizing
bacteria and free ammonia concentration
showed no short-term inhibition of ammonia
oxidation during the OUR test performance.
Fux (2003) calculated also nitrite nitrogen
oxidation at levels as high as 80 mg NH3 l-1.
Temperature
The temperature parameter was kept in the
range of 30-35oC for most of the period
described in order to maintain stable oxidation of ammonia to nitrite (Paper III). Temperature was gradually lowered starting from
February 2005 to reach values around 30oC in
April 2005. It was aimed at operating the
reactor without additional heat supply and
making use of the natural temperature of the
influent supernatant.
5.2.3. Anammox process
Free ammonia and free nitrous acid
Figure 7 presents the results of the Anammox reactor performance over the investigation period. The initial total inorganic nitrogen concentration was gradually increased
until the Anammox reactor capacity reached
0.9 g N m-2 d-1 in the initial months of the
two-step system operation. Nitrite nitrogen
concentrations exceeding 30 mg l-1 appeared
in the reactor at several instances and significantly affected the process. After process
inhibition in August 2003, a slow enhancement of the reactor capacity was obtained
during the year 2004. For the year 2004, the
efficiency of the process was on average 84%
(Paper III). The internal recirculation of the
effluent started in November 2004 caused
accumulation of the nitrate nitrogen, which
was a probable cause of the process disturbance in March 2005. But no previous studies proved this effect (Strous et al., 1999; Fux,
Concentrations of free ammonia that exceeded 20 mg NH3 l-1 in the partial nitritation
reactor did not cause inhibition of Nitrosomonas species (Paper I). This observation could
signify the acclimation of ammonia-oxidizing
bacteria as a result of long-term exposure to
high free ammonia concentrations. Such
observations should be expected in the partial nitritation reactors highly loaded with
ammonium. Additionally, based on the results of routine profiles (Trela et al., 2004d,
2005) (examples presented in Paper I and II)
performed through the whole operational
period, it was calculated that free ammonia
concentration was stratified along the zones
with the average values of 22 mg NH3 l-1
(zone 1), 6 mg NH3 l-1 (zone 2) and 4 mg
NH3 l-1 (zone 3). Free nitrous acid concentration was occasionally elevated up to 5 mg
mg N l -1
800
700
N inorg in
600
N inorg out
500
400
300
200
100
01
-M
a
01 y -0
-J 3
u
01 n-0
-J 3
01 u l-A 03
u
01 g -S 03
e
01 p -0
-O 3
01 ct-0
-N 3
01 ov -D 03
e
01 c -0
-J 3
a
01 n-0
-F 4
01 eb-M 04
01 ar-0
-A 4
01 pr-0
-M 4
a
01 y -0
-J 4
un
01 -0 4
-J
01 u l-A 04
u
01 g -0
-S 4
e
01 p -0
-O 4
01 ct-0
-N 4
01 ov -D 04
e
01 c -0
-J 4
a
01 n-0
-F 5
01 eb-M 05
01 ar-0
-A 5
pr
-0
5
0
date
Fig. 7 Total inorganic nitrogen concentrations at the inflow and outflow of the Anammox reactor (based on Trela et al., 2004d, 2005).
33
Luiza Gut
TRITA LWR LIC 2034
2003).
Stable nitrate nitrogen production at the rate
NO3-N/(NH4-N+NO2-N) around 0.6 (theoretical value of 0.11) confirmed that also a
minor simultaneous nitrification could take
place as the conditions were not strictly anaerobic. The presence of nitrifying activity in
the suspension from the Anammox reactor
was demonstrated in Paper II and confirms
the previous calculations. Parallel removal of
nitrite and ammonium nitrogen was analysed
as well in Paper III. The average ratio NO2Nremoved/NH4-Nremoved equal to 1.22 was calculated for the year 2004, which confirms the
established Anammox process. The results
are promising for the full-scale operation
(Paper III and IV).
Total SS in the Anammox reactor established
as a moving-bed reactor was high and was
caused by the seeding with nitrifiers from R1
(Paper II). The changes in the hydraulics of
the Anammox reactor resulted in fluctuations
in the SS concentration from 65 to 6440 mg l1
(53-89% of VSS). An average value of SVI
amounting to 97 ml g-1 of the sludge accumulated in the Anammox reactor showed acceptable settling properties. To compare
other values, Dapena-Mora et al. (2005) gives
the SVI value of 123 ml g-1 to characterise an
SBR Anammox biomass during the start-up
phase. Wett (2005) showed also satisfying
settling properties of the activated sludge in a
SBR with SVI=116 ml g-1.
Dissolved oxygen (DO) concentration
The oxygen-limited conditions were attained
for the whole period described (Paper I, II,
III). The DO concentration was on average
0.1 mg O2 l-1. Occasional enhancement of the
DO concentration up to 0.5 mg O2 l-1 did not
cause inhibition of the Anammox bacteria
activity. The nitrifiers present in the activated
sludge of the Anammox reactor (Paper II)
coped with the increased oxygen concentration. A column installed after the partial
nitritation reactor played a role of deoxidising
the aerated liquid.
Influent nitrite-to-ammonium ratio (NAR) ratio
Assessment of the stable operation of the
Anammox reactor shown in Paper III demonstrated that the most efficient process
performance (87% of process efficiency) was
in the NAR range from 1.0 to 1.5. The concomitant removal of ammonium and nitrite
for the results presented in Paper III did not
deviate much from the theoretical value of
1.3, which confirmed the stable Anammox
process. Moreover, modelling results presented in Paper IV asserted that the influent
NAR is correlated well with high process
efficiency. These outcomes of the study
emphasise the importance of the partial nitritation process effectiveness.
pH parameter
The pH value was initially corrected in the
Anammox reactor by the addition of a base
solution to keep the pH value around 8.2.
According to the stoichiometry of the
Anammox process, it was expected that the
pH value increase in the Anammox process
would compensate for the pH value decrease
in the preceding step. Therefore in 2004, the
experiment of ceasing the pH correction was
performed. It appeared that the pH correction is not necessary in the system (Paper
III). During highly efficient nitrogen removal
the Anammox reactor was operated without
the pH correction and during that time
(2004) the pH increase between the influent
and effluent by the unit of 1 was calculated.
Similar to results presented in Paper III, Fux
(2003) reported as well an increase of the pH
value in the SBR with an established Anammox process. Wett (2005) demonstrated that
a single-stage SBR system with the Anammox
Influent load
The extension of the Anammox reactor
capacity is viable by imposing higher influent
nitrogen load with a concomitant monitoring
of nitrite nitrogen concentration in the reactor (Paper III, IV). The shortened HRT and
the decreased dilution rate were two direct
operational strategies to vary loading. The
introduction of higher nitrogen load was
analysed in parallel with the increase of total
inorganic nitrogen removal (Paper III, IV).
The highest influent load was calculated as
1.2 g N m-2 d-1 and corresponded to the highest system capacity 0.9 g N m-2 d-1 (August
2003).
34
Assessment of a partial nitritation/Anammox system for nitrogen removal
process could be operated with an intermittent aeration controlled by the pH signal.
April 2005. The activity of the Anammox
bacteria was not substantially lower due to
changes. It brings possibilities of savings on
heating.
NO2-N concentration in the reactor
Over the period of the Anammox reactor
operation the nitrite nitrogen concentration
was maintained on average below 30 mg l-1.
An inhibition of the Anammox bacteria
occurred when a long-term exposure to the
concentrations above 100 mg l-1 was analysed. The covariations between the variables
describing the 20-month operation of the
Anammox reactor presented in Paper IV
showed that the enhanced nitrite nitrogen in
the effluent decreases efficiency of nitrogen
removal in the Anammox reactor. Paper IV
scrutinized for the importance of monitoring
the NO2-N concentration during the start-up
period and the lessened inhibiting effect
during the stable operation of the Anammox
reactor. Fux (2003) demonstrated that the
conductivity gradient between the cycles in
the Anammox SBR reactor could be used as
a warning indicator before nitrite nitrogen is
measured in the effluent. Moreover, the
author demonstrates that a temporal enhancement of nitrite nitrogen concentration
up to 50 mg l-1 did not cause long-term inhibition during the operation of an Anammox
fixed-bed reactor. The exposure time seemed
to have more importance in the nitrite inhibition of Anammox organisms.
Presence of nitrifiers
An initially assumed phenomenon of seeding
the Anammox reactor with nitrifiers was
proved in Paper II. Despite the fact that the
Anammox reactor was established in a moving-bed system, the activated sludge gradually
developed due to detachment of the biofilm.
The nitrifying activity was mainly concentrated in the activated sludge present in the
reactor. When the dissolved oxygen concentration in the suspension taken from the
Anammox reactor was increased before the
OUR test (Paper II), the nitrifying activity
was analysed. This activity was on average 10
times lower than the activities in the partial
nitritation reactor.
5.2.4. Reaction rates
Batch tests were performed to provide information on an actual velocity of the
Anammox reaction in the system and to
check the stability of the process (Siembida,
2004).
During the experiment of the increase in the
influent nitrogen load in the period February
– July 2004 (Figure 3) the series of batch tests
was conducted with the supernatant and the
Kaldnes rings taken from the Anammox
reactor. An example of the course of reaction
in a batch test is shown in Figure 8. The
reaction rates for the Anammox culture obtained in this batch test were 0.7 g NH4-N
m-2 d-1 for ammonium nitrogen, 0.9 g NO2-N
m-2 d-1 for nitrite nitrogen and 1.4 g N m-2 d-1
for total inorganic nitrogen elimination.
These are the highest values calculated during
the whole experimental period. A slight nitrate nitrogen production was also observed
at the rate of 0.22 g NO3-N m-2 d-1. Table 13
summarizes the average values of the reaction rates for 6 consecutive tests. For these
tests the dilution factor H2O/supernatant of
1.5 was set in the Anammox reactor. The
increasing tendency in nitrogen removal rates
was observed with the parallel increase in the
influent nitrogen load (Paper III). It indicates
Hydraulic Retention Time (HRT)
During the start-up period, the HRT was set
at 3 days in order to ensure the efficiency of
the process. The strategy of increasing loadings was done by the decrease of the HRT to
2 days in July 2003. It resulted in an overloading of the system and the inhibition of
the Anammox culture by nitrite. As a result,
the HRT was set again at 3 days and kept at
that level until the end of the investigated
period.
Temperature
The optimal temperature for the Anammox
bacteria in the range of 30-35oC (Egli et al.,
2001; Fux, 2003) was maintained in the
Anammox reactor for most of the investigated period (Paper III). A decrease in the
temperature value was imposed step-by-step
in order to obtain values around 30oC in
35
Luiza Gut
TRITA LWR LIC 2034
160
140
120
180
160
140
100
120
100
80
80
60
mg O2 l-1
mg N l -1
200
COD
Total N
NH4-N
NO2-N
NO3-N
60
40
40
20
20
0
0
0'
0''
1
2
3
4
5
6
hours
Fig. 8 Example of a batch test to assess reaction rates (slope of lines) in the Anammox process
(0’ – sample from reactor; 0’’ – sample after addition of ammonium and nitrite) (based on Siembida, 2004).
Table 13. Average values of nitrogen removal rates for batch tests in the period March-May
2004.
Dilution factor
H2O/supernatant
1.5 : 1
Nitrogen removal rates
Number of tests
-2
-1
-2
-1
-2
-1
g NH4-N m d
g NO2-N m d
g Ninorg m d
0.39
0.40
0.70
6
an increase in the bacterial activity in the
Anammox reactor.
To compare, in August 2003, when the highest removal of the influent nitrogen load was
estimated, the nitrogen removal rate in the
Anammox process amounted to 0.7 g N m-2
d-1. It is in agreement with the values from
Table 13. The reaction rates presented in this
study are somewhat lower that the rate of 2.2
g N m-2 d-1 obtained by Hippen et al. (2001)
in a moving-bed Anammox reactor for
sludge liquor treatment. Moreover, Beier et
al. (1998) and Seyfried et al. (2001) investigated the single-stage deammonification
process in moving-bed pilot plants and found
values around 2 g N m-2 d-1. These are the
rates expressing the simultaneous nitritation
and Anammox processes. Rosenwinkel et al.
(2005) also assumed 2 g N m-2 d-1 of the
surface degradation capacity in the singlestage deammonification system. The comparison of the reaction rates is shown in
Table 7 in chapter 3.4.
6. I MPLICATIONS
FOR FULL SCALE IMPLEMENTATION
In the full-scale operation, an interplay of
two functional purposes of the system must
be taken into account; namely, to optimise a
sustainable and economically feasible fullscale system and to intensify biochemical
reactions. The capacity of a moving-bed
Anammox reactor should be recognised and
therefore there is a need for an established
and reliable reaction rate for the system in
order to calculate the size of the reactor.
6.1. Proposal for system configurations
As a result of this licentiate study, the assessment of options for the moving-bed
biofilm system for nitrogen removal from
ammonium-rich wastewater has been done.
Figure 9 presents the development degrees of
a WWTP initially operated as a traditional
nitrification/denitrification
system
(I)
through nitritation/denitritation (II) to ob36
Assessment of a partial nitritation/Anammox system for nitrogen removal
tain a two-step partial nitritation/Anammox
system with case-specific modifications (III
A-F).
I. Traditional
nitrification/denitrification
system represents a typical biological part
of a WWTP. The existing infrastructure
can be used as a base for introducing the
following modifications presented in options II and III A-F.
II. An intermediate system for establishing
the subsequent nitritation and denitritation processes is a solution for the plants
aiming at introducing in the future a twostep partial nitritation/Anammox system.
Another reason can be savings in operational costs on aeration and chemicals for
the pH control and the addition of carbon source for heterotrophic bacteria.
III. Two-step partial nitritation/Anammox
system.
feeding of the influent supernatant is therefore necessary to steadily operate the partial
nitritation process. The Anammox process
follows and the additional bypassing of the
supernatant to this reactor can mitigate
higher nitrite nitrogen concentration in the
reactor.
III-C. The B-option is modified with regard to
make use of the production of nitrous oxide
(N2O) and carbon dioxide in the nitritation
stage. It was proved during the experiments
that a substantial production of N2O in R1 of
the partial nitritation/Anammox system
occurred (Armand and Vikström, 2005). N2O
could be decomposed into dinitrogen gas. A
closed reactor system with collection of the
gas flow to use it for mixing could be an
operational option for the Anammox reactor.
The shape of the reactor has to be accordingly adjusted in this case. It is not known,
however, whether the Anammox bacteria can
transform nitrous oxide. If N2O is still present in the effluent gas flow, it can be collected separately and treated with other gases.
The excess gas system together with an internal gas recirculation rate should be taken into
account. This proposition is an alternative for
a mechanical stirring operational mode that is
a cause of damaging the biofilm carriers.
III-D. With time, the Anammox reactor
seeded with the nitrifying microorganisms
could be switched to the reactor mode where
a simultaneous partial nitritation/Anammox
(SPNA) process takes place. In this option,
the operation of the partial nitritation reactor
as the first stage must be modified. Less
aeration would be necessary as the effluent
nitrite-to-ammonium ratio could be below
1.3. The bypassing of the influent supernatant to the inflow to R2 is again a safety
measure to cope with the occasional peaks of
nitrite nitrogen concentrations. As the effluent from the system contains nitrate nitrogen,
a pre-denitrification step is proposed. The
advantage of placing the denitrification step
before R1 consists in using the denitrifying
volume for the purpose of coping with occasional insufficient total inorganic nitrogen
elimination. The organic acids present in the
supernatant might be enough to denitrify the
effluent nitrate nitrogen concentration when
As a result of the investigations presented in
this work, the following options for process
configurations are proposed:
III-A. This thesis assesses the most important
findings concerning stable operation of a
system consisting of two steps where a preceding step is operated as a preparatory phase
for the Anammox reaction in the succeeding
part. It is known that in order to establish a
moving-bed biofilm Anammox bacterial
culture the aerobic nitrifiers must be already
enriched on the carrier elements. Therefore,
in order to switch an operation mode from
aerobic to the oxygen-limited must be done
at a proper time during the start-up period by
investigating the biofilm structure. The heterotrophic biofilm culture could be also
initially developed on a support material but
the inhibitory effect of alcohols on the
Anammox culture should be accounted for.
The start-up period can last up to 8 months.
In this system, the effluent nitrogen concentration is expected at the amount of around
10% of the influent nitrogen load.
III-B. Pre-denitrification added to the system
would enable higher total nitrogen removal
efficiency through removal of the residual
NO3-N concentrations in the effluent from
the system. The bypassing with the step
37
Luiza Gut
TRITA LWR LIC 2034
C
C
I
II
Settling
tank
(buffer)
R1
Nitritation
R2
DN
R1
Nitrification
Settling
tank
(buffer)
Settling
tank
Settling
tank
III-A
R1
Par tial
nitritation
Settling
tank
(buffer)
Stepfeeding
III-B
R1
DN Par tial
nitritation
R2
Anammox
Settling
tank
Bypassing
Settling
tank
R2
Anammox
Settling
tank
(buffer)
S ettling
tank
Recirculation
Stepfeeding
Bypassing
III-C
DN
Settling
tank
(buffer)
R1
Partial
nitritation
Excess gases
Bypassing
Settling
Settling
tank
tank
R2
Anammox
Flow of gas for mixing and N 2O removal
Recirculation
Bypassing
III-D
R1
Partial
nitritation
DN
Settling
tank
(buffer)
Recirculation
of gases
Settling
tank
Settling
tank
R2
SPNA
Recirculation
Bypassing
III-E
Settling
tank
Settling
tank
Settling
tank
B ypa ssing
R2
DN
R1
Partial
nitritation
Settling
tank
(buffer)
Settling C
tank
Settling
tank
R2
SPNA
DN
Flow of gas for mixing and N 2O removal
Bypassing
Recirculation
of gases
Settling
tank
III-F
DN
Settling
tank
(buffer)
R2
SPNA
R1
SPNA
Recirculation
Fig. 9 Proposed moving-bed biofilm systems for nitrogen removal from ammonium-rich wastewater (DN – denitrification; SPNA – Simultaneous Partial Nitritation/Anammox).
38
Assessment of a partial nitritation/Anammox system for nitrogen removal
moval in the case of deficiency of the organic
material. The buffer tank is compulsory in all
the options to avoid the influence of detrimental sludge and scum injections to the
system.
It has to be emphasized that the presented
modifications are not exclusive options for
the Anammox system. Case-specific argumentation should be used to choose the most
suitable option for a particular plant with
regard to flexibility of dealing with different
side-streams generated at the plant. Wett
(2005) gives a successful example of a shift
from a functioning nitritation/denitritation
system towards a stepwise enrichment of the
biomass with the autotrophic Anammox
bacteria. The author argues that substantial
savings on aeration, stirring and pumping
energy were obtained. van Loosdrecht and
Salem (2005) propose a decision support
chart that motivates the choice of the sludge
digester liquids treatment process with regard
to three case-specific aspects: the limiting
process, the limiting factor (e.g. sludge retention time, COD availability, aeration costs)
and the presence of a counter ion for ammonium (normally bicarbonate, but sometimes
chloride and fatty acids).
The research conducted at both the Royal
Institute of Technology and the experience
from the operation of a full-scale deammonification plant at the Hattingen WWTP in
Germany (Rosenwinkel and Cornelius, 2005;
Rosenwinkel et al., 2005) show possibilities
to obtain an efficient nitrogen removal in one
moving-bed biofilm reactor. Moving-bed
biofilm reactors are recommended for the
Anammox bacteria as in the biofilm it is
possible to develop internal anoxic zones in
the biofilm layer. Oxygen-limited conditions
in a reactor initially operated in aerobic conditions and seeded with the Anammox bacteria can result in cooperation between aerobic
and anaerobic ammonia oxidizers. Movingbed reactors can be operated with intermittent aeration or different aeration rates can
be set in separate reactors.
it is recycled at the inflow. If the predenitrification is used, the recycled effluent
might contribute to seeding with the Anammox bacteria. Methanol and other alcohols
cannot be used as an external source of carbon because it inhibits the Anammox bacteria.
III-E. In comparison to the D-option, the
denitrification reactor is placed at the end of
the system, after the settling tank. Technically, this option is much easier in operation.
The addition of an external easy biodegradable material might be necessary. The introduction of the internal flow of gases for
mixing and the removal of nitrous oxide
together with the recirculation of gases (similar to the option III-C) is also possible in the
post-denitrification step. The shape of the
reactor must be therefore designed to enable
the proper mixing regime. The aerobic conditions in the SPNA reactor are obligatory for
the process, the DO range 1-2 mg O2 l-1. An
inspection of the biofilm thickness is necessary in the SPNA system. The pH correction
is not necessary; the pH value is the range
7.8-8.2. The temperature from 25oC to 35oC
is optimal for the coexistence of ammonia
oxidising and Anammox bacteria.
III-F. If a stable SPNA process can be established, the influent nitrogen load can be
coped with by a system consisting of two
deammonifying reactors in series. The reactors could be equally loaded with the nitrogen by means of bypassing of the supernatant
flow or the second SPNA reactor might work
as a safety volume. Setting oxygen-limited
conditions by proper adjustment of a mixing
regime would be the bottleneck of such system. A pre-denitrification is the best complement to the system to meet effluent standards.
In the options III-A – III-F, the sludge separation units collect the excess sludge with
predominance of the nitrifying biomass. The
nitrifying and Anammox sludge can be collected separately and used respectively to
facilitate nitrification process in the main
wastewater treatment system and seed the
denitrifying units to support nitrogen re39
Luiza Gut
TRITA LWR LIC 2034
•
6.2. System technology with partial
nitritation/Anammox
A system with a partial nitritation followed by
an Anammox process as one- or two-step
technology may interact with different steps
of the WWTP and may be supplemented by
various pre-treatment or post-treatment
steps. The following examples are given
below.
Post-treatment of the effluent:
•
Excess ammonium may be treated by an
ammonium separation method or be oxidized to nitrite and recycled back to the
partial nitritation/Anammox step.
•
Excess nitrite or nitrate may be removed
by heterotrophic denitrification with an
internal or external carbon source.
Pre-treatment of the influent:
•
Increase of the ammonium content in the
supernatant due to special handling of the
excess sludge before digestion with the
use of mechanical, physical, chemical or
biological sludge minimization methods
(or special handling methods of the digested sludge, like thermal or chemical
conditioning methods).
•
Removal of a part of ammonium before
partial nitritation/Anammox by the use
of methods like ammonia stripping, precipitation of magnesium ammonium
phosphate or ion exchange.
•
Use of a fraction of the supernatant to
oxidize ammonium into nitrite to supply
it to a one-step partial nitritation/Anammox in order to increase the
reaction rates.
•
Improved separation of suspended solids
before a partial nitritation/Anammox
system in order to increase the fraction of
nitritation and Anammox bacteria in the
suspended solids or biofilm in the reactors.
As a final point, a system with partial nitritation/Anammox may meet very high emission
standards by the use of pre-treatment, posttreatment and special handling of the gas
phase. Of course, additional treatment units
imply investments and operational costs.
Savings in the mainstream methods of nitrogen removal must therefore balance these
costs. Some of the potential advantages of a
partial nitritation/Anammox system are
relatively low flows of water and air (in comparison to the main stream processes), high
temperature of the supernatant, low energy
demand, small usage of chemicals and possibilities to significantly improve the mainstream processes by reducing the nitrogen
load and the use of seeding effects of nitritation and Anammox bacteria.
6.3. Overall recommendations
The performed pilot-plant experiments with
the goal to study the influence of different
parameters controlling the two-step partial
nitritation/Anammox process enabled to give
recommendations for full-scale implementations of nitrogen removal from ammoniumrich wastewater. The recommendations are
grouped as follows.
Special handling of the gas phase or produced sludge in the
partial nitritation/Anammox system:
•
•
Formed Anammox bacteria may also
have an important role to improve nitrogen removal efficiency or reduce the necessary amount of carbon source in heterotrophic denitrification.
The gas phase from the partial nitritation
process may contain traces of nitrous oxides; if this stream cannot be handled internally, it may be transferred to a nitrification or denitrification step in the main
stream (e.g. activated sludge basins, postdenitrification step, etc.) or handled separately for instance in a compost filter.
General comments:
•
Formed nitritation bacteria may be important to improve the nitrification process in the main stream and all of the return sludge or its fraction may be seeded
into e.g. the aeration basin.
40
Start-up of a full-scale Anammox is a
limiting factor in all system configurations. System with the cultures developed
both as the activated sludge (e.g. SBR
technology) and as the biofilm (e.g. moving-bed biofilm reactor) can be applied.
Assessment of a partial nitritation/Anammox system for nitrogen removal
•
•
Kaldnes rings make the process more
compact and less sensitive. In a movingbed Kaldnes biofilm reactor, the HRT
can be lower than in the SBR reactors,
which will result in savings on reactors’
volumes. The cost of carrier materials
should be regarded as profitable in the
long way run because it results in future
much higher operation flexibility and robustness.
•
Production of N2O is expected in the
partial nitritation reactor due to side reactions occurring together with the suppressed nitrite oxidation.
•
It is 11% of the influent nitrogen load to
the Anammox reactor that is by theory
discharged from the system as nitrate nitrogen. It is thus obligatory to take into
account the nitrate nitrogen production
in the Anammox reactor to meet effluent
standards. Post- or pre-denitrification designed before or after a partial nitritation/Anammox system can be an option
to remove nitrate nitrogen. The effluent
from an Anammox system can be even
directed to the denitrification unit in the
main stream of a WWTP.
•
choice of the system with the Anammox
process.
The research experience from this work
and the full-scale Hattingen WWTP
(Rosenwinkel et al., 2005) shows that the
start-up period can last up to 8 months
with the strategy of developing the
Anammox culture on the previously established nitrifying biofilm. The experience from the STRASS WWTP (Wett,
2005) showed a step-by-step approach in
scaling up the deammonification process
but the total start-up period took as
much as 2.5 years.
The design of the partial nitritation/Anammox system must complement the WWTP design. Quality and
quantity changes of the supernatant must
be taken into account.
•
Mass balance calculations of inorganic
nitrogen forms should be done with regards of designing a partial nitritation/Anammox system in full scale.
•
The distribution of the reactors’ volumes
in the partial nitritation/Anammox system is dependent on the growth rates of
the respective bacterial cultures.
Reaction rates and system capacity:
•
The reaction rates around 1.2 g N m-2 d-1
and HRT=3 d with 1 m3 of the Kaldnes
carriers in the reactor of 2 m3 (50% of
volumetric filling, 500 m2 of the established biofilm and 1.8 m3 of the liquid in
the reactor) can cope with the load oscillating around 0.34 kg N m-3 d-1; it corresponds to the influent nitrogen concentration of as much as 1000 g m-3. The
increase of the reactor volume by around
13% should be taken into account in fullscale design due to Kaldnes filling.
•
Higher load should be imposed as the
strategy for extending system capacity
with a simultaneous monitoring of the
on-line conductivity readouts. A sudden
peak of conductivity may be a signal of
an enhanced nitrogen concentration in
the Anammox reactor.
System configurations:
Biogas generated during sludge digestion
or heat from heat exchangers can be used
as energy source for aeration and heating
purposes in the partial nitritation/Anammox system.
Design:
•
•
A full-scale partial nitritation/Anammox
system design is dependent on the sludge
generation pattern and the size of a
WWTP. Local conditions influence the
41
•
The bypassing of the influent supernatant
to further zones of the partial nitritation
reactor (step feeding) can allow for more
stable culture in that reactor.
•
Bypassing of the influent supernatant at
the inflow to the Anammox reactor can
be used to fulfil stoichiometry of the
Anammox process and as a safety measure in case of an overproduction of nitrite. The rate of the bypass flow can be
adjusted with the help of conductivity
measurements.
Luiza Gut
TRITA LWR LIC 2034
drop of the pH value and alkalinity consumption) is a proposal for an optimal
operation strategy for the partial nitritation reactor.
Avoidance of problems:
•
•
•
A buffer tank is needed in front of the
system to exclude the suspension in the
supernatant and work as a safety step to
prevent dumping of unwanted wastewater.
Storing supernatant and supplying it
during e.g. cleaning of centrifuges can
cope with uneven flows of supernatant.
It is advised to place the system as close
to a sludge processing unit as possible to
take advantage of high supernatant’s
temperature, decrease losses of heat and
avoid seasonal problems with frozen
pipes.
•
Frequent clogging of pipes requires regular maintenance procedure.
•
Other authors (Seyfried et al., 2001;
Dapena-Mora et al., 2005; Rosenwinkel et
al., 2005) reported calcium, iron and
phosphorous precipitation on the Kaldnes material. The content of Ca, Fe and P
salts should be analysed in the influent
stream to prevent the carriers’ damage by
precipitation.
•
Changes in the ammonium nitrogen
concentration in the influent can be
monitored by the conductivity parameter
in the partial nitritation step.
•
On-line control of the system should
consist of a pH-electrode at the outflow
from the partial nitritation reactor to
maintain the proper effluent nitrite-toammonium ratio.
•
On-line monitoring of the inorganic
nitrogen removal in the Anammox reactor can be done by measurements of
conductivity in the influent and effluent,
which could detect deviations from the
optimal nitrogen removal capacity.
•
An increase of the pH value in the
Anammox reactor can be a monitoring
indicator of an undisturbed reaction.
Modelling:
•
If the data for modelling are gathered
purposefully, modelling of the historical
data is a powerful tool in understanding
of covariations in the process variables as
well as allowing for the assessment of different system configurations.
•
Scale-up problems can be simulated by
the use of deterministic models. Calibration of the deterministic models requires
however proper experimental pilot-plant
configuration.
Equipment:
•
Operation of a moving-bed reactor is
dependent on the shear forces imposed
on the biofilm carriers by mixing; therefore, the mixing speed and a type of mixing unit in a full-scale moving-bed reactor
should be chosen carefully.
•
The mixing speed in both reactors should
be different due to the fact that the aeration unit in the partial nitritation reactor
puts carriers into mixing as well. In the
Anammox reactor, however, keeping
oxygen-limited conditions requires different type of mixers or lower speed of mixing to avoid the destruction of Kaldnes
rings.
•
Frequent exchange of electrodes and
rotary piston elements in pumps is necessary due to the reactivity of the liquor.
Control and monitoring:
•
On-line adjustment of the dissolved
oxygen concentration in the bulk liquid
based on the on-line pH readouts (proper
42
Assessment of a partial nitritation/Anammox system for nitrogen removal
7. F INAL
The assessment of the efficient nitrogen
removal in the whole system resulted in the
following conclusions:
CONCLUSIONS
The following conclusions concerning the
partial nitritation reactor can be stated:
•
•
•
•
Suitable adjustments of the parameters
like pH, DO concentration, temperature,
and HRT enabled to obtain two-year stable operation of the partial nitritation reactor.
The proper nitrite-to-ammonium ratio at
the outflow was obtained for most of the
period investigated. OUR tests, profile
performance, univariate and multivariate
data analyses confirmed the stable process operation.
The most robust partial oxidation of
ammonia to nitrite was in the first zone
of the reactor, which was demonstrated
by the OUR tests and profile performance.
A disturbance of the partial nitritation
reactor operation could be due to almost
total alkalinity consumption in zone 1 of
the reactor.
•
All tools used in the study proved to be
applicable in assessing the performance
of the two-step moving-bed partial nitritation/Anammox system.
•
Variable characteristics of the influent
supernatant and an enhanced nitrite nitrogen concentration in the Anammox
reactor are two factors that substantially
influence stable operation of the pilot
plant and can periodically decrease the efficiency of the process.
•
FISH analyses proved the presence of
ammonia-oxidizing bacteria in the partial
nitritation reactor and the Anammox bacteria in the second reactor.
•
Dynamic detachment of the biofilm and
seeding of the reactor with the nitrifying
sludge from the partial nitritation reactor
can explain periodical increases of the
suspended solids in the moving-bed
biofilm Anammox reactor.
•
Nitrifying activity in the partial nitritation
reactor is present in the biofilm whereas
in the Anammox reactor minor contribution of the nitrifying activity was detected
only in the suspended solids.
•
Process bottlenecks were recognised as
the dissolved oxygen concentration in
both reactors and nitrite nitrogen concentration increase in reactor 2.
•
Profiles of inorganic nitrogen forms were
a tool to monitor the system performance.
•
The two-step process can be successfully
monitored by conductivity measurements.
The main findings concerning the Anammox
process are as follows:
•
•
The operation of the Anammox reactor
over the period of two years gave efficient inorganic nitrogen removal.
A proper nitrite-to-ammonium ratio
(NAR) can be in the range 1.0-1.5 for the
most efficient nitrogen removal in the
Anammox reactor. The NAR is dependent on the partial nitritation reactor performance.
•
Dilution of the effluent from the partial
nitritation reactor was a reliable strategy
for extending the capacity of the Anammox reactor.
•
The pH correction appeared to be unnecessary in the Anammox reactor. During stable operation of the reactor an increase of the pH value was calculated.
The literature review and the experimental
work presented in this thesis proved that the
technology with the application of the partial
nitritation/ Anammox system is a sustainable
and cost-effective alternative for nitrogen
removal from ammonium-rich wastewater.
43
Luiza Gut
8. F URTHER
TRITA LWR LIC 2034
the partial nitritation reactor can be lower
than the stoichiometric value of 1.3. It
implies savings on aeration in converting
ammonia to nitrite. It needs further investigations.
RESEARCH WORK
The following implications for further research work can be presented:
•
•
•
•
•
The digestion process at the Himmerfjärden WWTP should be scrutinised
with the aim of recognising factors influencing the quality of the influent supernatant.
There is still lack of information concerning the inhibitory effect of nitrite on
Anammox bacteria. The initial concentration of nitrite nitrogen over 100 mg l-1
during short-term batch test was not inhibitory for the Anammox bacteria. Reliable on-line nitrite monitoring is a future
research goal.
Biochemical reactions of the Anammox
bacteria could be scrutinized for the possibility of utilization of N2O in their metabolism. If this phenomenon were
proved, it would open possibilities of
dealing with the production of an unwanted greenhouse gas.
A possibility of symbiosis of Anammox
and Nitrosomonas bacteria and the distribution of the activity between the activated sludge and biofilm in the reactor
under oxygen-limited conditions should
be checked in batch tests.
Nitrifying activity in the Anammox reactor can positively affect the performance
of the Anammox reactor, as the nitriteto-ammonium ratio in the effluent from
44
•
The research could be extended into an
option to perform partial nitritation and
Anammox processes in one reactor. In
the reactor configuration with a simultaneous partial nitritation/Anammox processes, the intermittent aeration operational mode could be applied.
•
The ability of the Anammox culture to
recover from the time of stress has not
yet been investigated. A possibility of
temporal acclimation of Anammox bacteria to lower temperatures could provide
incentive for future commercial sale of
the bacteria for seeding purposes.
•
The main line of a WWTP can be constantly seeded with the developed
Anammox sludge to increase capacity or
to gradually change the system operational mode from traditional to more
cost-effective. The upgrading procedure
needs further investigations.
•
The inspection of the biofilm thickness
and structure could be a monitoring tool,
especially during the start-up phase. The
effect of changing the feed volume and
agitation speed on the biofilm thickness
is necessary to investigate.
Assessment of a partial nitritation/Anammox system for nitrogen removal
9. R EFERENCES
Abeling U. and Seyfried C. F. (1992) Anaerobic – aerobic treatment of high-strength ammonium
wastewater – nitrogen removal via nitrite. Wat. Sci. Tech., 26(5-6), 1007-1015.
Abma W. R., Mulder J. W., van Loosdrecht M. C. M., Strous M. and Tokutomi T. (2005) Anammox demonstration on full scale in Rotterdam. In: Proceedings of the 3rd Leading Edge Conference on Water and Wastewater Treatment Technologies, 6-8 June 2005, Sapporo, Japan.
Aguado D., Zarzo M., Ferrer J. and Seco A. (2005) A multivariate methodology for detecting
operational shifts: application to a Sequencing Batch Reactor. In: Proceedings of the IWA
Specialized Conference “Nutrient Management in Wastewater Treatment Processes and Recycle
Streams”, 19-21 September 2005, Kraków, Poland, 755-764.
Ahn Y. H. and Kim H. C. (2004) Nutrient removal and microbial granulation in an anaerobic
process treating inorganic and organic nitrogenous wastewater. Wat. Sci. Tech., 50(6), 207215.
Ahn Y. H., Hwang I. S. and Min K. S. (2004) Anammox and partial denitritation in anaerobic
nitrogen removal from piggery waste. Wat. Sci. Tech., 49(5-6), 145-153.
Anthonisen A. C., Loehr R. C., Prakasam T. B. S. and Srinath E. G. (1976) Inhibition of nitrification by ammonia and nitrous acid. Journal WPCF, 48(5), 835-852.
Armand B. and Vikström P. (2005) Mätning av lustgasemission från vätskeytor vid pilotanläggning för
deammonifikation. K-Konsult Arbetsmiljö VVS AB.
Austermann-Haun U., Meyer H., Seyfried C. F. and Rosenwinkel K. H. (1999) Full scale experiences with anaerobic/aerobic treatment plants in the food and beverage industry. Wat.
Sci. Tech., 40(1), 305-312.
Bae W., Baek S., Chung J. and Lee Y. (2002) Optimal operational factors for nitrite accumulation
in batch reactors. Biodegradation, 12, 359-366.
Banas J., Płaza E., Styka W. and Trela J. (1999) SBR technology used for advanced combined
municipal and tannery wastewater treatment with high receiving water standards. Wat. Sci.
Tech., 40(4-5), 451-458.
Beier M., Hippen A., Seyfried C. F., Rosenwinkel K. H. and Johansson P. (1998) Comparison of
different biological treatment methods for nitrogen-rich wastewaters. European Water
Management, 2(1), 61-66.
Bock E., Schmidt I., Strüven R. and Zart D. (1995) Nitrogen loss caused by denitrifying Nitrosomonas cells using ammonium or hydrogen as electron donors and nitrite as electron
acceptor. Arch. Microbiol., 163, 16-20.
Broda E. (1977) Two kinds of lithotrophs missing in nature. Z. Allg. Microbiol., 17, 491-493.
Carrera J., Baeza J. A., Vicent T. and Lafuente J. (2003) Biological nitrogen removal of highstrength ammonium industrial wastewater with two-sludge system. Wat. Res., 37(17),
4211-4221.
Carucci A., Chiavola A., Majone M. and Rolle E. (1999) Treatment of tannery wastewater in a
sequencing batch reactor. Wat. Sci. Tech., 40(1), 253-259.
Cema G., Płaza E., Surmacz-Górska J., Trela J. and Miksch K. (2005a) Study on evaluation of
kinetic parameters for Anammox process. In: Proceedings of the IWA Specialized Conference
“Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 19-21 September
2005, Kraków, Poland.
Cema G., Płaza E., Surmacz-Górska J. and Trela J. (2005b) Activated sludge and biofilm in the
Anammox reactor – cooperation or competition? In: Integration and optimisation of urban
sanitation systems, Joint Polish-Swedish Reports, No 12. Royal Institute of Technology, Stockholm, 2005, TRITA-AMI.REPORT, in press.
45
Luiza Gut
TRITA LWR LIC 2034
Chen P. H. (1996) Assessment of leachates from sanitary landfills: impact of age, rainfall, and
treatment. Environment International, 22(2), 225-237.
Choi E., Eum Y., Gil K. I. and Oa S. W. (2004) High strength nitrogen removal from nightsoil
and piggery wastes. Wat. Sci. Tech., 49(5-6), 97-104.
Ciudad G., Robilar O., Muñoz P., Ruiz G., Chamy R., Vergara C. and Jeison D. (2005) Partial
nitrification of high ammonia concentration wastewater as a part of a shortcut biological
nitrogen removal process. Process Biochem., 40, 1715-1719.
Cornelius A. and Rosenwinkel K.-H. (2002) Aerob/anoxische Deammonifikation stickstoffhaltiger Abwässer im KALDNES®-Biofilmverfahren. KA-Wasserwirtschaft, Abwasser, Abfall,
49, 1398-1403. (In German).
Dapena-Mora A., Trigo C., Fernández I., Vázquez-Padín J. R., Figureoa M., Arrojo B., Garrido J.
M., Mosquera-Corral A., Campos J. L. and Méndez R. (2005) Start-up of Anammox
process: different reactor configurations. In: Proceedings of the IWA Specialized Conference
“Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 19-21 September
2005, Kraków, Poland, 855-864.
Dapena-Mora A., Campos J. L., Mosquera-Corral A., Jetten M. S. M. and Méndez R. (2004) Stability of the ANAMMOX process in a gas-lift reactor and a SBR. Journal of Biotech.,
110(2004), 159-170.
Dalsgaard T., Thamdrup B. and Canfield D. E. (2005) Anaerobic ammonium oxidation (anammox) in the marine environment. Research in Microbiology, 156, 457-464.
Dalsgaard T., Canfield D. E., Petersen J., Thamdrup B. and Acuña-González J. (2003) N2 production by the anammox reaction in the anoxic water column of Golfo Dulce, Costa
Rica. Nature, 422, 606-608.
Dalsgaard T. and Thamdrup B. (2002) Factors controlling anaerobic ammonium oxidation with
nitrite in marine sediments. Applied and Environmental Microbiology, 68(8), 3802-3808.
de Silva D. G. and Rittmann B. E. (2001) Simultaneous nitrification and denitrification in onestage activated sludge systems. In: Proceedings of the Water Environment Federation Conference
“Plant Operations & Maintenance: Meeting the Challenges at Small & Medium-Sized Industrial and
Municipal Wastewater Treatment Plants”, June 18–20, 2000, Portland, Oregon.
Devol A. H. (2003) Solution to a marine mystery. Nature, 422, 575-576.
Dijkman H. and Strous M. (1999) Process for ammonia removal from wastewater. Patent
PCT/NL99/00446.
Długołęcka M. (2004) Experimental study on nitrogen removal system with deammonification process. Master
of Science Thesis, Gdańsk University of Technology, Poland.
Domínguez B., Lobo A., Moreno-Ventas X. and Tejero I. (2005) Model-based evaluation of
heterotrophs and anammox population competition coexistence in a N-removal reactor.
In: Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment
Processes and Recycle Streams”, 19-21 September 2005, Kraków, Poland, 1197-1202.
Dong X. and Tollner E. W. (2003) Evaluation of Anammox and denitrification during anaerobic
digestion of poultry manure. Bioresource Technology, 86, 139-145.
Egli K. (2003) On the use of anammox in treating ammonium-rich wastewater. PhD Thesis, Swiss Federal
Institute of Technology, Zurich. DISS. ETH NO. 14886.
Egli K., Fanger U., Alvarez P. J. J., Siegrist H., van der Meer J. R. and Zehnder A. J. B. (2001)
Enrichment and characterization of an anammox bacterium from a rotating biological
contactor treating ammonium-rich leachate. Arch. Microbiol., 175, 198-207.
Ekman M. (2005) Modelling and control of bilinear systems. Application to the activated sludge process. PhD
thesis, Uppsala University, Sweden.
46
Assessment of a partial nitritation/Anammox system for nitrogen removal
Engström P. (2004). The importance of anaerobic ammonium oxidation (Anammox) and anoxic nitrification
for N removal in coastal marine sediments. PhD thesis, Göteborgs Universitet, Sweden.
Eriksson L., Johansson E., Kettaneh-Wold N. and Wold S. (2001) Multi- and Megavariate Data
Analysis. Principles and Applications. Umetrics AB, Sweden.
Finnson A. (1994) Computer simulations of full-scale activated sludge processes. Licentiate thesis, Royal
Institute of Technology, Stockholm, Sweden. TRITA-VAT-1941.
Fukarawa K., Rouse J. D., Imajo U., Sugino H. and Fujii T. (2001) Establishment of an anaerobic
ammonium-oxidizing culture in continuous flow treatment with non-woven biomass carrier. In: Proceedings of the Water Environment Federation Conference “Plant Operations & Maintenance: Meeting the Challenges at Small & Medium-Sized Industrial and Municipal Wastewater Treatment Plants”, June 18–20, 2000, Portland, Oregon.
Fux C., Marchesi V., Brunner I. and Siegrist H. (2004) Anaerobic ammonium oxidation of ammonium-rich waste streams in fixed-bed reactors. Wat. Sci. Tech., 49(11-12), 77-82.
Fux C. (2003) Biological nitrogen elimination of ammonium-rich sludge digester liquids. PhD Thesis, Swiss
Federal Institute of Technology, Zurich, Switzerland. DISS. ETH NO. 15018.
Fux C., Boehler M., Huber P., Brunner I. and Siegrist H. (2002) Biological treatment of ammonium-rich wastewater by partial nitritation and subsequent anaerobic ammonium oxidation (anammox) in a pilot plant. Journal of Biotech., 99, 295-306.
Gebara F. (1999) Activated sludge biofilm wastewater treatment system. Wat. Res., 33(1), 230238.
Glixelli T. M. (2003) Treatment of ammonium-rich waste streams with deammonification process. Master of
Science Thesis, Cracow University of Technology, Poland.
Gujer W., Henze M., Takashi M. and van Loosdrecht M C. M. (1999) Activated sludge model
No. 3. Wat. Sci. Tech., 39(1), 183-193.
Gut L. (2003) Deammonification as a novel biological process for treatment of ammonium-rich wastewater –
experimental study. Master of Science Thesis, Royal Institute of Technology, Stockholm,
Sweden, TRITA-LWR-EX-03-21.
Gut L. and Płaza E. (2003) Laboratory-scale study on treatment of high-strength ammonium
wastewater. In: Integration and optimisation of urban sanitation systems, Joint Polish-Swedish Reports, No. 11. TRITA-LWR REPORT 1650-8610-SE, 98-108.
Güven D., Dapena A., Kartal B., Schmid M. C., Maas B., van de Pas-Schoonen K., Sozen S.,
Mendez R., Op den Camp H. J. M., Jetten M. S. M., Strous M. and Schmidt I. (2005)
Propionate oxidation by and methanol inhibition of anaerobic ammonium-oxidizing bacteria. Applied and Environmental Microbiology, 71(2), 1066-1071.
Güven D., van de Pas-Schoonen K., Schmid M. C., Strous M., Sozen S., Orhon D., Jetten M. S.
M., and Schmidt I. (2004) Effects of carbon compounds on the activity of Anammox. In:
Proceeding of “EU 5th framework IcoN Symposium: Anammox: new sustainable N-removal from waste
water”. 21-23 January 2004, Ghent, Belgium.
Hallin S. (1998) Dynamics of denitrifying populations in activated sludge processes with nitrogen removal. PhD
Thesis, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Hao X. and van Loosdrecht M. C. M. (2004) Model-based evaluation of COD influence on a
partial nitrification-Anammox biofilm (CANON) process. Wat. Sci. Tech., 49(11-12), 8390.
Hao X. and van Loosdrecht M. C. M. (2003) A proposed sustainable BNR plant with the emphasis on recovery of COD and phosphate. Wat. Sci. Tech., 48(1), 77-85.
Hao X., Heijnen J. J. and van Loosdrecht M. C .M. (2002a) Model-based evaluation of temperature and inflow variations on a partial nitrification–ANAMMOX biofilm process. Wat.
Res., 36, 4839-4849.
47
Luiza Gut
TRITA LWR LIC 2034
Hao X., Heijnen J. J. and van Loosdrecht M. C. M. (2002b) Sensitivity analysis of biofilm model
describing a one-stage completely autotrophic nitrogen removal (CANON) process. Biotechnol. Bioeng., 77(3), 266-277.
Hassanzadeh R. (2005) Partial nitritation/anammox as a biological process for treatment of high-strenght
nitrogen wastewater. Master of Science Thesis, Royal Institute of Technology, Stockholm,
Sweden, LWR-EX-05-32.
Harabasz J. (2004) The ways of minimizing sludge production in wastewater treatment plants with nutrient
removal. Master of Science Thesis, Cracow University of Technology, Poland.
Heijnen J. J. and van Loosdrecht M. C. M. (1999) Patent. Application N.: 09/237.603. Patent
No.: US 6.183.642 B1.
Heijnen J. J. and van Loosdrecht M. C. M. (1997) Patent. Application N.: 97202539.9. Patent
No.: EP 0 826 639 A1.
Hellinga C., van Loosdrecht M. C. M. and Heijnen J. J. (1999) Model based design of a novel
process for nitrogen removal from concentrated flows. Mathematical and Computer Modelling
of Dynamic Systems, 5(4), 351-371.
Hellinga C., Schellen A. A. J. C., Mulder J. W., van Loosdrecht M. C. M. and Heijnen J. J. (1998)
The SHARON process: an innovative method for nitrogen removal from ammoniumrich wastewater. Wat. Sci. Tech., 37(9), 135-142.
Helmer C., Tromm C., Hippen A., Rosenwinkel K. H., Seyfried C. F. and Kunst S. (2001) Single
stage biological nitrogen removal by nitritation and anaerobic ammonium oxidation in
biofilms systems. Wat. Sci. Tech., 43(1), 311-320.
Helmer C., Kunst S., Juretschko S., Schmid M. C., Schleifer K-H. and Wagner M. (1999) Nitrogen loss in a nitrifying biofilm system. Wat. Sci. Tech., 39(7), 13-21.
Helmer C. and Kunst S. (1998) Simultaneous nitrification/denitrification in an aerobic biofilm
system. Wat. Sci. Tech., 37(4-5), 183-187.
Henze M., Harremoёs P., Jansen J. la C. and Arvin E. (2002) Wastewater treatment: Biological and
Chemical Processes. Springer, Heidelberg, 430 p.
Henze M., Grady C. P. L., Gujer W., Marais G. V. R. and Matsuo T. (1987) A general model for
single-sludge wastewater treatment systems. Wat. Res., 21(5), 505-515.
Hippen A. (2001) Einsatz der Deammonifikation zur Behandlung hoch stickstoffhaltiger Abwässer. PhD
Thesis, des Institutes für Siedlungswasserwirtschaft und Abfalltechnik der Universität
Hannover (in German).
Hippen A., Helmer C., Kunst S., Rosenwinkel K. H. and Seyfried C. F. (2001) Six years’ practical
experience with aerobic/anoxic deammonification in biofilm systems. Wat. Sci. Tech.,
44(2-3), 39-48.
Hippen A., Johansson P., Beier M., Rosenwinkel K. H. and Seyfried C. F. (1999) Direct deammonification, a novel cost effective biological removal process for nitrogen-rich wastewaters. In: Proceedings of the “Nitrogenfjerning og biologisk fosforfjerning”. Oslo, 2-4 February 1999.
Hippen A., Rosenwinkel K. H., Baumgarten G. and Seyfried C. F. (1997) Aerobic deamonification: a new experience in the treatment of wastewaters. Wat. Sci. Tech., 35(10), 111-120.
Horeglad P. (2001) Pilot plant study at Himmerfjärden – evaluation of start-up operation. Master of Science Thesis, Royal Institute of Technology, Sweden, AVAT-EX-2000-03.
Huang Y., Yuan Y. and Li Y. (2004) The enrichment and cultivation of Anammox microorganisms from sludge of wastewater treatment plant. In: Proceedings of the “4th IWA World Water
Congress and Exhibition”, Marrakech, 19-24 September 2004.
48
Assessment of a partial nitritation/Anammox system for nitrogen removal
Hwang B. H., Hwang K. Y., Choi E. S., Choi D. K. and Jung J. Y. (2000) Enhanced nitrite buildup in proportion to increasing alkalinity/NH4+ ratio of influent in biofilm reactor. Biotechnology Letters, 22, 1287-1290.
Hwang I. S., Min K. S., Choi E. and Yun Z. (2004) Nitrogen removal from piggery waste using
the combined Sharon and Anammox process. In: Proceedings of the “4th IWA World Water
Congress and Exhibition”, Marrakech, 19-24 September 2004.
Imajo U., Tokutomi T. and Furukawa K. (2004) Granulation of Anammox microorganisms in
up-flow reactors. Wat. Sci. Tech., 49(5-6), 155-163.
Jansen J. C., Nyberg U., Aspegren H. and Andersson B. (1993) Handling of anaerobic digester
supernatant combined with full nitrogen removal. Wat. Sci. Tech., 27(5-6), 391-403.
Jeppsson U. (1996) Modelling aspects of wastewater treatment processes. PhD thesis, Lund Institute of
Technology, Lund, Sweden.
Jardin N., Hippen A., Seyfried C.F., Rosenwinkel K.-H. and Greulich F. (2001) Deammonifikation des Schlammwassers auf der Kläranlage Hattingen mit Hilfe des Schwebebettverfahrens. GWF, 142, 479-484. (In German).
Jetten M. S. M., Sliekers O., Kuypers M., Dalsgaard T., Van Niftrik L., Cirpus I., Van De PasSchoonen K., Lavik G., Thamdrup B., Le Paslier D., Op Den Camp H. J., Hulth S., Nielsen L. P., Abma W., Third K., Engstrom P., Kuenen J. G., Jorgensen B. B., Canfield D.
E., Sinninghe Damsté J. S., Revsbech N. P., Fuerst J., Weissenbach J., Wagner M.,
Schmidt I., Schmid M. and Strous M. (2003) Anaerobic ammonium oxidation by marine
and freshwater planctomycete-like bacteria. Appl Microbiol Biotechnol., 63, 107-114.
Jetten M. S. M., Schmid M., Schmidt I., Wubben M., van Dongen U., Abma W., Sliekers O.,
Revsbech N. P., Beaumont H. J. E., Ottosen L., Volcke E., Laanbroek H. J., Campos
Gomez J. L., Cole J., van Loosdrecht M., Mulder J. W., Fuerst J., Richardson D., Van de
Pas K., Mendez-Pampin R., Third K., Cirpus I., van Spanning R., Bollmann A., Nielsen L.
P., den Camp H. O., Schultz C., Gundersen J., Vanrolleghem P., Strous M., Wagner M.
and Kuenen J. G. (2002) Improved nitrogen removal by application of new nitrogencycle bacteria. Re/views in Environmental Science and Bio/Technology, 1, 51-63.
Jetten M. S. M., Wagner M., Fuerst J., van Loosdrecht M. C. M., Kuenen G. and Strous M. (2001)
Microbiology and application of anaerobic ammonium oxidation (‘anammox’) process.
Current Opinion in Biotechnology, 12, 283-288.
Jetten M. S. M., Strous M., van de Pas-Schoonen K. T., Schalk J., van Dongen U. G. J. M., van de
Graaf A. A., Logemann S., Muyzer G., van Loosdrecht M. C. M. and Kuenen J. G. (1999)
The anaerobic oxidation of ammonium. FEMS Microbiol. Rev., 22, 421-437.
Jetten M. S. M., Horn S. J. and van Loosdrecht M. C. M. (1997) Towards a more sustainable
municipal wastewater treatment system. Wat. Sci. Tech., 35(9), 171-180.
Jianlong W. and Jing K. (2005) The characteristics of anaerobic ammonium oxidation
(ANAMMOX) by granular sludge from an EGSB reactor. Process Biochemistry, 40, 19731978.
Jianlong W. and Ning Y. (2003) Partial nitrification under limited dissolved oxygen conditions.
Process Biochemistry, 39, 1223-1229.
Johansson P., Nyberg A., Beier M., Hippen A., Seyfried C. F. and Rosenwinkel K-H. (1998) Cost
efficient sludge liquor treatment. In: Integration and optimisation of urban sanitation systems, Joint
Polish-Swedish Reports, No 3. Royal Institute of Technology, Stockholm, TRITA-AMI Report 3048, 65-72.
Jönsson K., Grunditz C., Dalhammar G. and Jansen J. la C. (2000) Occurrence of nitrification
inhibition in Swedish municipal wastewaters. Wat. Res., 34(9), 2455-2462.
49
Luiza Gut
TRITA LWR LIC 2034
Keller J., Subramaniam K., Gösswein J. and Greenfield P. F. (1997) Nutrient removal from industrial wastewater using single tank sequencing batch reactors. Wat. Sci. Tech., 35(6), 137144.
Koch G., Egli K., Van der Meer J. R. and Siegrist H. (2000) Mathematical modelling of autotrophic denitrification in a nitrifying biofilm of a rotating biological contractor. Wat. Sci.
Tech., 41(4-5), 191-198.
Kreft J.-U., Picioreanu C., Wimpenny J. W. T. and van Loosdrecht M. C. M. (2001) Individualbased modelling of biofilms. Microbiology, 147, 2897-2912.
Kuai L. and Verstraete W. (1980) Ammonium removal by the oxygen-limited autotrophic nitrification-denitrification system. Appl. Environ. Microbiol., 64(11), 4500-4506.
Kuenen J. G. and Jetten M. S. M. (2001) Extraordinary anaerobic ammonium-oxidizing bacteria.
ASM News, 67, 456-463.
Kuypers M. M. M., Sliekers A. O., Lavik G., Schmid M., Jorgensen B. B., Kuenen J. G., Damsté
J. S. S., Strous M. and Jetten M. (2003) Anaerobic ammonium oxidation by anammox
bacteria in the Black Sea. Nature, 422, 608-611.
La Rocca N. (2001) Deammonification process with a pre-nitritation step to treat supernatant. Master of
Science Thesis, Royal Institute of Technology, Sweden, AVAT-EX-2000-02.
Li X., Zen G., Rosenwinkel K. H., Kunst S., Weichgrebe D., Cornelius A. and Yang Q. (2004)
Start up of deammonification process in one single SBR system. Wat. Sci. Tech., 50(6), 1-8.
MacGregor J. F., Yu H., Muñoz S. G. and Flores-Cerrillo J. (2005) Data-based latent variable
methods for process analysis, monitoring and control. Computers and Chemical Engineering,
29, 1217-1223.
Maurer M., Schwegler P. and Larsen T. A. (2003) Nutrients in urine: energetic aspects of removal
and recovery. Wat. Sci. Tech., 48(1), 37-46.
Mele G. (2005) Towards an effective and sustainable Anammox process: a pilot plant study.
Master of Science Thesis, Royal Institute of Technology, Sweden, TRITA-LWR-EX-0527.
Miettinen T., Hurse T. J., Connor M. A., Reinikainen S.-P. and Minkkinen P. (2004) Multivariate
monitoring of a biological wastewater treatment process: case study at Melbourne water’s
western treatment plant. Chemometrics and Intelligent Laboratory Systems, 73, 131-138.
Mohan S., Dennison V., Schmidt M., Richardson D. and Cole J. (2004) We all need friends – but
why can’t Anammox bacteria live alone? In: Proceeding of “EU 5th framework IcoN Symposium:
Anammox: new sustainable N-removal from waste water”. 21-23 January 2004, Ghent, Belgium.
Mossakowska A. (1994) Nitrifiering av rejektvatten med SBR-teknik på Bromma reningsverk. Licentiate
Thesis, Royal Institute of Technology, Stockholm, TRITA-VAT-1942 (in Swedish).
Mulder A. (2003) The quest for sustainable nitrogen removal technologies. Wat. Sci. Tech., 48(1),
67-75.
Mulder A., van der Graaf A. A., Robertson L. A. and Kuenen J. G. (1995) Anaerobic ammonium
oxidation discovered in a denitrifying fluidized bed reactor. FEMS Microbiol. Ecol., 16(3),
177-184.
Mulder M. W., van Loosdrecht M. C. M., Hellinga C. and Kempen R. (2001) Full-scale application of the SHARON process for treatment of rejection water of digested sludge dewatering. Wat. Sci. Tech., 43(11), 127-134.
Mulder A. (1992) Anoxic ammonium oxidation. US patent documents 427849(5078884). United
States patent.
Musiał A. (2000) Charakterystyka cieczy osadowych powstających w wyniku przeróbki osadów ściekowych.
Master of Science Thesis, Cracow University of Technology, Poland (in Polish).
50
Assessment of a partial nitritation/Anammox system for nitrogen removal
Nielsen M., Bollmann A., Sliekers O., Jetten M., Schmid M., Strous M., Schmidt I., Larsen L. H.,
Nielsen L.P. and Revsbech N. P. (2005) Kinetics, diffusional limitation and microscale
distribution of chemistry and organisms in a CANON reactor. FEMS Microbiol. Ecol., 51,
247-256.
Nikolić A. and Hultman B. (2003) Combined nitritation and chemical denitrification - a new
treatment system for nitrogen removal from landfill leachates. Vatten, 59(1), 39-45.
Obrzut L. (1997) Odcieki z wysypisk komunalnych. Ekoprofit, 5, 32-36, (in Polish).
Ochoa J. C., Colprim J., Palacios B., Paul E. and Chatellier P. (2002) Active heterotrophic and
autotrophic biomass distribution between fixed and suspended systems in a hybrid biological reactor. Wat. Sci. Tech., 46(1-2), 397-404.
Orantes J. C. and González-Martínez S. (2003) A new low-cost biofilm carrier for treatment of
municipal wastewater in a moving bed reactor. Wat. Sci. Tech., 48(11-12), 243-250.
Ottosen L., Nielsen L. P., Larsen L. H. and Revsbech N. P. (2004) On-line sensors for Anammox
control. In: EU 5th framework IcoN Symposium: Anammox: new sustainable N-removal
from waste water. In: Proceeding of “EU 5th framework IcoN Symposium: Anammox: new sustainable N-removal from waste water”. 21-23 January 2004, Ghent, Belgium.
Płaza E., Trela J., Gut L., Löwén M., Szatkowska B. (2003a) Deammonification process for
treatment of ammonium rich wastewater. In: Integration and optimisation of urban sanitation
systems, Joint Polish-Swedish Reports, No 10. Royal Institute of Technology, Stockholm,
TRITA-AMI REPORT 3004-SE, 77-87.
Płaza E., Trela J., Löwén M., Szatkowska B. and Gut L. (2003b) Nitrogen removal from ammoniumrich waste streams with low content of biodegradable organic matter. ÅFORSK Final Report, Project
01-41.
Płaza E., Trela J. and Hultman B. (2002) Treatment of ammonium-rich waste streams with low
content of organic matter. In: Proceedings of the “Enviro 2002 IWA World Water Congress”.
Melbourne, 7-12 April 2002.
Płaza E., Bosander J., Dahlberg A. G. and Hellström B. G. (1990) Operational experience with
phosphorus and nitrogen removal at the Himmerfjärden Plant, Sweden. Wat. Sci. Tech.,
22(7-8), 283-284.
Płaza E., Bosander J. and Trela J. (1989) Factors affecting biological nitrogen removal efficiency
in a large wastewater treatment plant. Wat. Sci. Tech., 24(7), 121-131.
Płaza E., Trela J. and Hultman B. (2001) Impact of seeding with nitrifying bacteria on nitrification process efficiency. Wat. Sci. Tech., 43(1), 155-163.
Poth M. and Focht D. D. (1985) 15N kinetic analysis of N2O production by Nitrosomonas europaea: an examination of nitrifier denitrification. Appl. Environ. Microbiol., 49(5), 11341141.
Pynaert K., Wyffels S., Sprengers R., Boeckx P., Van Cleemput O. and Verstraete W. (2002)
Oxygen-limited nitrogen removal in a lab-scale rotating biological contractor treating an
ammonium-rich wastewater. Wat. Sci. Tech., 45(10), 357-363.
Rittmann B. E. and McCarty P. L. (2001) Environmental Biotechnology: Principles and Applications.
International Edition, 2001. McGraw-Hill Education.
Rosenwinkel K.-H. and Cornelius A. (2005) Deammonification in the moving-bed process for
the treatment of wastewater with high ammonia content. Chem. Eng. Technol., 28(1), 49-52.
Rosenwinkel K.-H., Cornelius A. and Thöle D. (2005) Full-scale application of the deammonification process for the treatment of sludge water. In: Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 19-21 September 2005, Kraków, Poland, 483-491.
51
Luiza Gut
TRITA LWR LIC 2034
Ruiz G., Jeison D., Rubilar O., Ciudad G. and Chamy R. (2005) Nitrification-denitrification via
nitrite accumulation for nitrogen removal from wastewaters. Bioresource Technology, in press.
Ruiz G., Jeison D. and Chamy R. (2003) Nitrification with high nitrite accumulation for the
treatment of wastewater with high ammonia concentration. Wat. Res., 37(6), 1371-1377.
Rysgaard S., Glud R. N., Risgaard-Petersen N. and Dalsgaard T. (2004) Denitrification and
anammox activity in Arctic marine sediments. Limnology and Oceanogrraphy, 49(5), 1493–
1502.
Salem S., Berends D. H. J. G., van der Roest H. F., van der Kuij R. J. and van Loosdrecht M. C.
M. (2004) Full-scale application of the BABE technology. Wat. Sci. Tech., 50(7), 87-96.
Salem S., Berends D. H. J. G., Heijnen J. J. and van Loosdrecht M. C. M. (2003) Bioaugmentation by nitrification with return sludge. Wat. Res., 37, 1794-1804.
Samuelsson P. (2005) Control of nitrogen removal in activated sludge processes. PhD thesis, Uppsala University, Sweden.
Schmid M., Walsh K., Webb R., Rijpstra C., van de Pas-Schoonen K., Verbruggen M. J., Hill T.,
Moffett B., Fuerst J., Schouten S., Damsté J. S. S., Harris J., Shaw P., Jetten M. S. M. and
Strous M. (2003) Candidatus “Scalindua brodae”, sp. nov., Candidatus “Scalindua wagneri”, sp. nov., two new species of anaerobic ammonium oxidizing bacteria. System. Appl.
Microbiol., 26, 529-538.
Schmidt I, Batstone and Angelidaki I. (2004) Improved nitrogen removal in upflow anaerobic
sludge blanket (UASB) by incorporation of Anammox bacteria into the granular sludge.
Wat. Sci. Tech., 49(11-12), 69-76.
Schmidt I., Sliekers O., Schmid M., Bock E., Fuerst J., Kuenen J. G., Jetten M. S. M. and Strous
M. (2003) New concept of microbial treatment process for the nitrogen removal in
wastewater. FEMS Microbiol. Rev., 27, 481-492.
Schmidt I., Hermelink C., van de Pas-Schoonen K., Strous M., op den Camp H. J., Kuenen J. G.
and Jetten M. S. M. (2002a) Anaerobic ammonia oxidation in the presence of nitrogen
oxides (NOx) by two different lithotrophs. Applied and Environmental Microbiology, 68(11),
5351-5357.
Schmidt I., Sliekers O., Schmid M., Cirpus I., Strous M., Bock E., Kuenen J. G. and Jetten M. S.
M. (2002b) Aerobic and anaerobic ammonia oxidizing bacteria – competitors or natural
partners? FEMS Microbiology Ecology, 39, 175-181.
Schmidt I. and Bock E. (1997) Anaerobic ammonia oxidation with nitrogen dioxide by Nitrosomonas eutropha. Arch. Microbiol., 167, 106-111.
Seyfried C. F., Rosenwinkel K.-H. and Hippen A. (2002) Deammonification: a cost-effective
treatment process for nitrogen-rich wastewaters. In: WEFTEC 2002 Proceedings 75th Annual Conference and Exposition. McCormick Place, Chicago, Illinois, USA, 28 September – 2
October 2002.
Seyfried C. F., Hippen A., Helmer C., Kunst S. and Rosenwinkel K.-H. (2001) One-stage deammonification: nitrogen elimination at low cost. Wat. Sci. Tech.: Water supply, 1(1) 71-80.
Siegrist H., Reithaar S., Koch G. and Lais P. (1998) Nitrogen loss in a nitrifying rotating contactor treating ammonium-rich wastewater without organic carbon. Wat. Sci. Tech., 38(8-9),
241-248.
Siegrist H. (1996) Nitrogen removal from digester supernatant - comparison of chemical and
biological methods. Wat. Sci. Tech., 34(1-2), 399-406.
Siembida B. (2004) An experimental study of an innovative nitrogen removal system for digester supernatant.
Master of Science Thesis, Cracow University of Technology.
Sinninghe-Damsté J. S., Strous M. and Abma W. (2002) Linearly concatenated cyclobutane (ladderane)
lipids. European patent application EP02079327.9
52
Assessment of a partial nitritation/Anammox system for nitrogen removal
Sliekers A. O., Haaijer S., Schmid M., Harhangi H., Verwegen K., Kuenen J. G. and Jetten M. S.
M. (2004) Nitrification and Anammox with urea as the energy source. System. Appl. Microbiol., 27, 271-278.
Sliekers A. O., Third K. A., Abma W., Kuenen J. G. and Jetten M. S. M. (2003) CANON and
Anammox in a gas-lift reactor. FEMS Microbiol. Lett., 218, 339-344.
Sliekers A. O., Derwort N., Campos Gomez J. L., Strous M., Kuenen J. G. and Jetten M. S. M.
(2002) Completely autotrophic nitrogen removal over nitrite in one single reactor. Wat.
Res., 36, 2475-2482.
Strous M., Fuerst J. A., Kramer E. H. M., Logemann S., Muyzer G., van de Pas-Schoonen K. T.,
Webb R., Kuenen J. G. and Jetten, M. S. M. (1999) Missing lithotroph identified as new
planctomycete. Nature, 400, 446-448.
Strous M., Kuenen J. G. and Jetten M. S. M. (1999) Key physiology of anaerobic ammonium
oxidation. Appl. Environ. Microbiol., 65, 3248-3250.
Strous M., Heijnen J. J., Kuenen J. G. and Jetten M. S. M. (1998) The sequencing batch reactor as
a powerful tool for the study of slowly growing anaerobic ammonium-oxidizing microorganisms. Appl. Microbiol. Biotechnol., 50, 589-596.
Strous M., van Gerven E., Zheng P., Kuenen J. G. and Jetten M. S. M. (1997) Ammonium removal from concentrated waste streams with the anaerobic ammonium oxidation
(Anammox) process in different reactor configuration. Wat. Res., 31(8), 1955-1962.
Surmacz-Górska J., Żabczyński S. and Miksch K. (2003) The start-up of the Anammox process
in the membrane-assisted bioreactor. In: Integration and optimisation of urban sanitation systems,
Joint Polish-Swedish Reports, No. 10. Royal Institute of Technology, Stockholm, 2003,
TRITA-LWR.REPORT 3004-SE, 67-76.
Surmacz-Górska J., Cichoń A. and Miksch K. (1997) Nitrogen removal from wastewater with
high ammonia nitrogen concentration via shorter nitrification and denitrification. Wat.
Sci. Tech., 36(10), 73-78.
Surmacz-Górska J., Gernaey K., Demuynak C., Vanrolleghem P. and Verstraete W. (1996) Nitrification monitoring in activated sludge by oxygen uptake rate (OUR) measurements. Wat.
Res., 30(5), 1228-1236.
Szatkowska B., Płaza E., Trela J., Bosander J. and Hultman B. (2005) Application of conductivity
measurements for monitoring of nitrogen removal in partial nitritation/Anammox process. In: Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 19-21 September 2005, Kraków, Poland, 717-724.
Szatkowska B. (2004) Treatment of ammonium-rich wastewater by partial nitritation/Anammox in a biofilm
system. Licentiate thesis, Royal Institute of Technology, Stockholm, Sweden. TRITALWR.LIC 2023.
Szatkowska B., Płaza E. and Trela J. (2004a). Nitrogen removal rates in the deammonification
process: batch experiments. In: Proceedings of the “4th IWA World Water Congress and
Exhibition”, Marrakech, 19-24 September 2004.
Szatkowska B., Płaza E., Trela J. and Hultman B. (2004b) Monitoring of nitrogen removal processes by use of conductivity measurements. Vatten, 60(2), 111-118.
Szatkowska, B., Płaza, E. and Trela, J. (2003a) Preliminary studies on deammonification process
kinetics. In: Integration and optimisation of urban sanitation systems, Joint Polish-Swedish Reports,
No. 10. Royal Institute of Technology, Stockholm, 2003, TRITA-LWR.REPORT 3004SE, 89-97.
Szatkowska B., Płaza E., Trela J. and Bąkowska A. (2003b) Influence of dissolved oxygen concentration on deammonification process performance. In: Integration and optimisation of ur53
Luiza Gut
TRITA LWR LIC 2034
ban sanitation systems, Joint Polish-Swedish Reports, No 11. Royal Institute of Technology,
Stockholm, 2003, TRITA-LWR.REPORT 3007 –SE, 121-131.
Tendaj-Xavier M. (1985) Biologisk behandling av rejektvatten från centrifugering av rötslam.
Licentiate thesis, Royal Institute of Technology, Stockholm, Sweden. TRITA-VAT-1851.
Thamdrup B. and Dalsgaard T. (2002) Production of N2 through anaerobic ammonium oxidation
coupled to nitrate reduction in marine sediments. Appl. Environ. Microbiol., 68(3), 13121318.
Third K. A. (2003) Oxygen management for optimisation of nitrogen removal in a sequencing batch reactor.
PhD Thesis, School of Biological Sciences and Biotechnology, Murdoch University,
Western Australia.
Third K. A., Sliekers A. O., Kuenen J. G. and Jetten M. S. M. (2001) The CANON system
(Completely Autotrophic Nitrogen-removal Over Nitrite) under ammonium limitation:
interaction and competition between three groups of bacteria. System. Appl. Microbiol., 24,
588-596.
Tomita R. S., Park S. W. and Sotomayor O. A. Z. (2002) Analysis of activated sludge process
using multivariate statistical tools – PCA approach. Chemical Engineering Journal, 90, 283290.
Trela J., Płaza E., Gut L., Szatkowska B. and Hultman B. (2005) Deammonification, en ny process för
behandling av avloppsströmmar med hög kvävehalt – fortsatta experiment i pilot-skala. VA-Forsk
Rapport, Nr 2005-14, (In Swedish).
Trela J., Płaza E., Szatkowska B., Hultman B., Bosander J. and Dahlberg A-G. (2004a) Deammonifikation som en ny process för behandling av avloppsströmmar med hög kvävehalt.
Vatten, 60(2), 119-127, (in Swedish).
Trela J., Płaza E., Szatkowska B., Hultman B., Bosander J. and Dahlberg A-G. (2004b). Swedish
experience with combined nitritation and anammox: pilot plant experiments. In: Proceedings of the “EU 5th framework IcoN Symposium: Anammox: new sustainable N-removal from waste
water”, Ghent, Belgium, 21-23 January 2004.
Trela J., Płaza E., Szatkowska B., Hultman B., Bosander J. and Dahlberg A. G. (2004c). Pilot–
plant experiments with combined nitritation and anaerobic ammonium oxidation
(Anammox) in biofilm system. In: Proceedings of the “IWA World Water Congress and exhibition”, Marrakech, 19-24 September 2004.
Trela J., Płaza E., Szatkowska B., Gut L. and Hultman B. (2004d) Deammonifikation som en ny process för behandling av avloppsströmmar med hög kvävehalt – experiment i pilot-skala. VA-Forsk Rapport. Nr 2004-09, (In Swedish).
Trela J. (2000) Intensification of biological nitrogen removal in a two-phase activated sludge process with predenitrification. PhD Thesis, Royal Institute of Technology, Stockholm, TRITA-AMI Report
3081.
Trimmer M., Nicholls J. C. and Deflandre B. (2003) Anaerobic ammonium oxidation measured
in sediments along the Thames estuary, United Kingdom. Appl. Environ. Microbiol., 69,
6447-6454.
Turk O. and Mavinic D. S. (1989) Maintaining nitrite build-up in a system acclimated to free
ammonia. Wat. Res., 23, 1383-1388.
Udert K. M., Fux C., Münster M., Larsen T. A., Siegrist H. and Gujer W. (2003) Nitrification and
autotrophic denitrification of source-separated urine. Wat.Sci.Tech., 48(1), 119-130.
van Benthum W. A. J., Garrido J. M., Mathijssen J. P. M., Sunde J., van Loosdrecht M. C. M. and
Heijnen J. J. (1998) Nitrogen removal in intermittently aerated biofilm airlift reactor. Journal of Environmental Engineering, 124, 239-248.
54
Assessment of a partial nitritation/Anammox system for nitrogen removal
van de Graaf A. A. , de Bruijn P., Robertson L. A., Jetten M. S. M. and Kuenen J. G. (1996)
Autotrophic growth of anaerobic ammonium-oxidizing micro-organisms in a fluidized
bed reactor. Microbiology UK, 142, 2187-2196.
van de Graaf A. A., Mulder A., de Bruijn P., Jetten M. S., Robertson L. A. and Kuenen J. G.
(1995) Anaerobic oxidation of ammonium is a biologically mediated process. Appl. Environ. Microbiol., 61, 1246-1251.
van der Zandt E., Claessen V., Hommel B. and Berends D. (2005) First outing for the BABE
process. Water 21, 4, 36-37.
van Dongen L. G. J. M., Jetten M. S. M. and van Loosdrecht, M. C. M. (2001a) The combined
Sharon/Anammox Process, A sustainable method for N-removal from sludge water. STOWA Report, IWA Publishing, London, UK.
van Dongen L. G. J. M., Jetten M. S. M. and van Loosdrecht M. C. M. (2001b). The SharonAnammox process for treatment of ammonium rich wastewater. Wat.Sci.Tech., 44(1), 153160.
van Dongen G. and Geuens L. (1998) Multivariate time series analysis for design and operation
of a biological wastewater treatment plant. Wat. Res., 32(3), 691-700.
Van Hulle S. (2005) Modelling, simulation and optimisation of autotrophic nitrogen removal processes. PhD
Thesis, University of Ghent.
Van Hulle S., Maertens J. and Vanrolleghem P. A. (2003) Performance of a CANON and an
Anammox biofilm under different hydrodynamic conditions. In: Proceedings of IWA Biofilm
symposium. Cape Town, South Africa, September 14-18 2003.
van Kempen R., Mulder J. W., Uijterlinde C. A. and van Loosdrecht M. C. M. (2001) Overview:
full scale experience of the SHARON process for treatment of rejection water of digested
sludge dewatering. Wat. Sci. Tech., 44(1), 145-152.
van Loosdrecht M. C. M. and Salem S. (2005) Biological treatment of sludge digester liquids. In:
Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment Processes and Recycle Streams”, 19-21 September 2005, Kraków, Poland, 13-22.
van Loosdrecht M. C. M., Hao X., Jetten M. S. M. and Agama W. (2004) Use of Anammox in
urban wastewater treatment. Wat. Sci. Tech.: Water Supply, 4(1), 87-94.
van Loosdrecht M. C. M., Van Benthum W. A. J. and Heijnem J. J., (2000) Integration of nitrification and denitrification in biofilm airlift suspension reactors. Wat. Sci. Tech., 41(4-5), 97103.
van Loosdrecht M. C. M. and Jetten M. S. M. (1998) Microbiological conversions in nitrogen
removal. Wat. Sci. Tech., 38(1), 1-7.
van Loosdrecht M. C. M. and Jetten M. S. M. (1997) Method for treating ammonia-comprising
wastewater. Patent PCT/NL97/00482.
van Loosdrecht M. C. M., Jetten S. M. M. and Horn S. J. (1997) Towards a more sustainable
municipal wastewater treatment system. Wat. Sci. Tech., 35(9), 171-180.
Van Niftrik L. A., Fuerst J. A., Damsté S. J. S., Kuenen J. G., Jetten M. S. M. and Strous M.
(2004) The anammoxosome: an intracytoplasmic compartment in anammox bacteria.
FEMS Microbiology Letters, 233, 7-13.
Verstraete W. and Philips S. (1998) Nitrification-denitrification processes and technologies in
new contexts. Environmental Pollution, 102, S1, 717-726.
Volcke E. I. P., Van Hulle S. W. H., van Loosdrecht M. C. M. and Vanrolleghem P.A. (2003)
Generation of Anammox-optimal nitrite:ammonium ratio with Sharon process: usefulness of process control? In: 9th IWA Specialised Conference Design, Operation and Economics of
Large Wastewater Treatment Plants. 1-4 September 2003, Praha, Czech Republic.
55
Luiza Gut
TRITA LWR LIC 2034
Volcke E. I. P., Hellinga C., Van Den Broeck S., van Loosdrecht M. C. M. and Vanrolleghem
P.A. (2002a) Modelling the SHARON process in view of coupling with Anammox. In:
Proceedings of the 1st International Scientific and Technical Conference on Technology, Automation and
Control of Wastewater and Drinking Water Systems (TiASWiK’02). Gdańsk-Sobieszewo, Poland, June 19-21 2002, 65-72.
Volcke E. I. P., van Loosdrecht M. C. M. and Vanrolleghem P.A. (2002b) Influence of operating
parameters on the performance of a continuously aerated Sharon reactor. Med. Fac. Landbouww., Univ. Gent, 67/4, 209-212.
Wang C, Wang B and Wang L. (2004) Nitrogen loss in a BAF by autotrophic denitrification
(ANAMMOX) with oxygen limitation. In: Proceedings of the “4th IWA World Water Congress
and Exhibition”, Marrakech, 19-24 September 2004.
Welander U. (1998) Characterization and treatment of municipal landfill leachates. Licentiate thesis. Dep.
of Biotechnology, Lund University, Sweden.
Wett B. (2005) Solved scaling problems for implementing deammonification of rejection water.
In: Proceedings of the IWA Specialized Conference “Nutrient Management in Wastewater Treatment
Processes and Recycle Streams”, 19-21 September 2005, Kraków, Poland, 389-396.
Wett B. and Alex J. (2003) Impacts of separate rejection water treatment on the overall plant
performance. Wat. Sci. Tech., 48(4), 139-146.
Wilsenach J. A., Maurer M., Larsen T. A. and van Loosdrecht M. C. M. (2003) From waste treatment to integrated resource management. Wat. Sci. Tech., 48(1), 1-9.
Wold S., Sjöström M and Eriksson L. (2001) PLS-regression: a basic tool of chemometrics.
Chemometrics and Intelligent Laboratory Systems, 58, 109-130.
Wold S., Esbensen K. and Geladi P. (1987) Principal Component Analysis. Chemometrics and Intelligent Laboratory Systems, 2, 37-52.
Wyffels S., van Hulle S. W. H., Boeckx P., Volcke E. I. P., van Cleemput O., Vanrolleghem P. A.
and Verstraete W. (2004) Modelling and simulation of oxygen-limited partial nitritation in
a membrane-assisted bioreactor (MBR). Biotechnol. Bioeng., 86(5), 531-542.
Wyffels S., Boeckx P., Pynaert K., Volcke E. I. P., Verstraete W. and van Cleemput O. (2003)
Sustained nitrite accumulation in a membrane-assisted bioreactor (MBR) for the treatment of ammonium-rich wastewater. J. Chem. Technol. Biotechnol., 78, 412-419.
Yang W., Vollertsen J. and Hvitved-Jacobsen T. (2003) Nitrite accumulation in the treatment of
wastewaters with high ammonia concentration. Wat. Sci. Tech., 48(3), 135-141.
Ye R. W. and Thomas S. M. (2001) Microbial cycles: physiology, genomics and applications.
Current Opinion in Microbiology, 4, 307-312.
Yoo H., Ahn K. H., Lee H. J., Lee K. H., Kwak Y. J., Song K. G. (1999) Nitrogen removal from
synthetic wastewater by simultaneous nitrification and denitrification (SND) via nitrite in
an intermittently-aerated reactor. Wat. Res., 33(1), 145-154.
Ødegaard H., Gisvold B. and Strickland J. (2000) The influence of carrier size and shape in the
moving bed biofilm process. Wat. Sci. Tech., 41(4-5), 383-391.
Ødegaard H., Rusten B. and Westrum T. (1994) A new moving bed biofilm reactor – applications
and results. Wat. Sci. Tech., 29(10-11), 157-165.
Other references
AnoxKaldnes group web page: <www.anoxkaldnes.com> (September 2005).
BIOMATH web page <http://biomath.ugent.be/lab/> (September 2005).
Cranfield University web page , Institute of Water and Environment
<http://www.silsoe.cranfield.ac.uk/iwe/iwe.htm> (October 2005).
56
Assessment of a partial nitritation/Anammox system for nitrogen removal
Genoscope web page, the French National Sequencing Center
<http://www.genoscope.cns.fr/> (September 2005).
Grontmij Water and Reststoffen web page <http://www.grontmij.nl> (August 2005).
Hulth S. (2005) Personal communications. Institutionen för Kemi, Göteborgs Universitet, Göteborg.
IcoN project web page <http://biomath.ugent.be/projects/infopage.php?EG-ICON1> (October 2005).
Kurita Water Industries Ltd., Japan, web page <http://www.kurita.co.jp/english/> (September
2005).
Nagaoka University web page <http://ecolab.nagaokaut.ac.jp/~envaio_e/> (October 2005)
Paques home page <http://www.paques.nl/> (September 2005) and the “Major breakthrough in
nitrogen removal” web page
<http://www.paques.nl/paques/webPages.do?pageID=200427> (April 2005).
SNAP process web page: <http://www.civil.kumamotou.ac.jp/suishitu/paper/snap/snap02.htm> (August 2005).
Strous M. (2004) The online Anammox resource: pioneering microbiology for a sustainable future. <www.anammox.com> (October 2005).
Umetrics AB web page <http://www.umetrics.com/> (September 2005).
Unisense A/S web page <http://www.unisense.com> (October 2005).
United States Department of Agriculture web page; Coastal Plains, Soil, Water and Plant Research Center; Research Project: Development of New Generation Low-Cost Treatment
of Ammonia to Benefit the Environment and Promote Sustainable Livestock Production
<http://www.ars.usda.gov/research/projects/projects.htm?ACCN_NO=408509> (October 2005).
University of München web page <http://www.mytum.de/navigation_view> (October 2005).
University of Queensland web page, Centre for Bacterial Biodiversity and Identification
<http://www.smms.uq.edu.au/index.html?page=17441&pid=0> (October 2005).
University of Vienna web page, Department of Microbial Ecology <http://www.microbialecology.net/envgenomics.asp> (October 2005).
57
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Related manuals

Download PDF

advertisement