Redalyc.Treatment of textile effluent containing indigo

Acta Scientiarum. Technology
ISSN: 1806-2563
eduem@uem.br
Universidade Estadual de Maringá
Brasil
Conceição, Vinicius; Bentes Freire, Flavio; Querne de Carvalho, Karina
Treatment of textile effluent containing indigo blue dye by a UASB reactor coupled with pottery clay
adsorption
Acta Scientiarum. Technology, vol. 35, núm. 1, enero-marzo, 2013, pp. 53-58
Universidade Estadual de Maringá
Maringá, Brasil
Available in: http://www.redalyc.org/articulo.oa?id=303226544008
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ISSN printed: 1806-2563
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Doi: 10.4025/actascitechnol.v35i1.13091
Treatment of textile effluent containing indigo blue dye by a UASB
reactor coupled with pottery clay adsorption
Vinicius Conceição1*, Flavio Bentes Freire2 and Karina Querne de Carvalho3
1
Departamento Acadêmico de Química e Biologial, Universidade Tecnológica Federal do Paraná, Rua Deputado Heitor Alencar Furtado, 4900, 81280-340,
Curitiba, Paraná, Brazil. 2Departamento Acadêmico de Construção Civil, Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brazil.
3
Universidade Tecnológica Federal do Paraná, Campo Mourão, Paraná, Brazil. *Author for correspondence. E-mail: viniciusmasquetti@hotmail.com
ABSTRACT. This study aimed to evaluate the treatment of a synthetic textile wastewater containing the
blue indigo dye in a UASB (upflow anaerobic reactor), on a bench scale, followed by pottery clay
adsorption. The system monitoring was verified by the following physical and chemical parameters: pH,
alkalinity, volatile acids, COD and removal of color. The adsorption tests using pottery clay (construction
debris) as an alternative adsorbent material were performed on a jar test equipment. The results showed
satisfactory effectiveness in removing color and organic matter (COD) by the UASB, at the order of 69 and
81.2%, respectively. The color removal using ceramic clay as an alternative adsorbent material was 97% for
the concentration of 200 g L-1 of adsorbent, evidencing that the use of pottery clay as adsorbent material
had significant and promising results, and may be used as a post-treatment unit for removal of dyes present
in textile effluents, and since construction debris currently represents a major environmental problem, its
use in wastewater treatment may become an alternative to a proper destination of this waste.
Keywords: UASB reactor, adsorption, Indigo Blue dye, pottery clay.
Tratamento de efluente têxtil sintético contendo corante Azul Índigo em reator UASB,
seguido por adsorção em cerâmica de argila
RESUMO. Este trabalho teve como objetivo avaliar o tratamento de um efluente têxtil sintético, contendo
o corante Azul Índigo, em um reator UASB (reator anaeróbico de fluxo ascendente), em escala de bancada,
seguido por adsorção em cerâmica de argila. O monitoramento do sistema foi verificado pelos seguintes
parâmetros físico-químicos: pH, alcalinidade, ácidos voláteis, DQO e remoção de cor verdadeira.
Os ensaios de adsorção utilizando cerâmica de argila (entulho da construção civil) como material
adsorvente alternativo foram realizados em um aparelho “jar test”. Os resultados obtidos demonstraram
eficiência satisfatória na remoção de cor e matéria orgânica (DQO) pelo UASB, da ordem de 69 e 81,2%,
respectivamente. A remoção de cor, utilizando a cerâmica de argila como material adsorvente alternativo,
foi de 97% para a concentração de 200 g L-1 de adsorvente, constatando-se que, a utilização da cerâmica de
argila como material adsorvente apresentou resultados significativos e promissores, podendo esta ser
utilizada como unidade de pós-tratamento na remoção de corantes presentes em efluentes têxteis. Como o
entulho da construção civil configura-se atualmente em grande problema ambiental, sua utilização no
tratamento de efluentes pode se tornar uma alternativa para um destino adequado desse resíduo.
Palavras-chave: reator UASB, adsorção, corante Azul Índigo, cerâmica de argila.
Introduction
The growing concern with the preservation of
water resources in the last few years has become
evident both by the establishment of environmental
standards increasingly restrictive, or by the charges,
according to the paying polluter and paying user
principles. Pollution and contamination of the water
bodies by different human activities have caused
several environmental, social, economic and of
public health problems.
Besides the economic importance, the textile
industries are also recognized by the high consumption
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of water and generation of hazardous effluents.
Management measures related to the improvement of
production techniques, which lead to a lower water
consumption, and the treatment and reuse of generated
effluents, certainly enable a reduction of environmental
impacts. The textile industry is one of the largest
producers of liquid effluents. Approximately 80 liters
of water are necessary to produce 1 kg of fabric.
However, there is reference to values in the order of
150 liters, being 80% of this volume discarded as
effluent and only 12% of the total composes the losses
by evaporation (HARRELKAS et al., 2009).
Maringá, v. 35, n. 1, p. 53-58, Jan.-Mar., 2013
54
The characteristics of these effluents depend on
the technology and the industrial processes used and
also the types of fibers and chemical products
employed, but it is known that the major problems
associated with the effluents are related to the high
amount of organic load, color, toxicity and salinity
(HARRELKAS et al., 2009). Several types of dyes
(natural, reactive, acids, cationic, among others) can
be used in textile industry, mainly during the dyeing
and finishing steps. These substances configure in an
important part of the pollution problems, once it is
estimated that 50% of the applied quantity to the
fabric fibers do not fix to them, subsequently forming
the wastewater (HARRELKAS et al., 2009). Besides
the toxicity, effluents with high color absorb the light
in the receiving bodies, affecting the balance of the
aquatic ecosystems (ALINSAFI et al., 2006).
The “AZO” dyes, for example, systematically
investigated by the scientific community, produce
aromatic carcinogenic amines, and were banned by
the textile sector in 2003, following the
recommendation of the European Community.
Several alternatives of treatment for these
effluents were reported in literature. It is worth
highlighting that, in full scale, an isolated unit hardly
will fulfill the restricted levels of discharge required
by the law, being necessary the development of
systems that integrate generally several unities. In
these cases, the main characteristic is the
complementation between the strengths and the
weaknesses points of each component, allowing
more effective results.
In this way, according to Assadi and Jahangirib
(2001), for textile effluents, additionally to the
biological treatment, the physical and chemical
methods are also used to remove coloring substances.
The anaerobic biological processes (HAROUN;
IDRIS, 2009; SANTOS et al., 2004) have been
prioritized, in relation to the aerobics (ALINSAFI
et al., 2006), due to the advantages such as lower
sludge generation, lower energy demand and lower
operational costs, but the studies that consider the
anaerobic/aerobic association also had been carried
out (KAPDAN; ALPARSLAN, 2005).
The chemical methods usually involve
coagulation followed by precipitation and chemical
sludge oxidation and the physical methods involve
mainly the adsorption on activated carbon
(SIRIANUNTAPIBOON et al., 2007) and at lower
scale, the membranes technology.
The various types of coal are widely used in
adsorption operations. The vegetable coal, for
example, is obtained from the burning of wood, i.e.,
derives from an activity that also implies in
environmental degradation.
Acta Scientiarum. Technology
Conceição et al.
Considering that the coal burning is somehow
inevitable, at least in India, due to power
generation plants, Rao and Rao (2006) have studied
the treatment of textile effluent by adsorption
together with the ashes generated in the process,
comparing the results with the activated carbon,
obtaining similar color removals of 96 and 98.5%,
respectively. However, this initiative can be
considered even a “palliative” and the search for
alternative adsorbent materials, also derived from
less aggressive activities, become a need of
researches related to the subject.
The building rubble of building industry is
perhaps the most heterogeneous among the
industrial wastes. It is made up of remains of
practically all-building materials (mortar, sand,
ceramic, concrete, wood, metal, paper, plastic, stone,
brick, ink, among others) and its chemical
composition is bound to the composition of each
one of its constituents.
Given the above, this study analyzed the
treatment of a synthetic textile effluent, through a
UASB reactor followed by an adsorption unit, in
which it was investigated the activated carbon and
the pottery clay as adsorbent materials to verify the
removal of organic material (COD) and color.
Material and methods
Synthetic textile wastewater
The basis of the wastewater used in the study
was chosen due to the simplicity to prepare large
volumes. Freire et al. (2008) used the same synthetic
wastewater (without adding indigo dyes) for the
performance and the fluid-dynamic analyses,
respectively, in an Anaerobic Fluidized Bed Reactor
(AFBR).
The composition of the synthetic textile effluent
used is presented in the Table 1, with the values based
on a concentration of organic material in terms of
COD in the order of 1,000 mg L-1. For different
concentrations of COD from the stipulated, it was
added the reactants in the desired proportion.
UASB Reactor
The bench-scale upflow anaerobic sludge
blanket reactor (UASB) used in the study, as
illustrated in the Figure 1, was built in acrylic with
volume of 1 L, height of 55 cm and diameter of
4.8 cm. The reactor has three sampling points along
its height, for biomass sampling. Initially, the reactor
was operated with flowrate of 2.5 L day-1 and,
subsequently, with more optimized results, with
flowrate of 4.5 L day-1, corresponding to HRT of
5.3h, at room temperature.
Maringá, v. 35, n. 1, p. 53-58, Jan.-Mar., 2013
Treatment of textile effluent by adsorption
55
Table 1. Composition of the synthetic textile wastewater.
Compound
Glucose
Urea
Nickel sulfate
Ferrous sulfate
Ferric chloride
Cobalt chloride
Selenium oxide
Monobasic potassium phosphate
Potassium phosphate dibasic
Sodium phosphate dibasic
Sodium bicarbonate
Indigo Blue Dye
-1
Concentration (mg L )
1,000
62.5
0.5
2.5
0.25
0.04
0.035
42.5
10.85
16.7
1,000
300
The monitoring of the reactor performance
treating the textile effluent was verified by the
following physical and chemical parameters: pH,
total alkalinity, volatile acids, COD and color
removal.
Figure 1. UASB reactor scheme.
The UASB reactor was inoculated with sludge of
an anaerobic reactor (AFBR) from the wastewater
treatment plant of the city of Umuarama, Paraná
State. The inoculation process through the already
“formed” biomass was adopted to accelerate the
obtainment of satisfactory results in the removal of
Acta Scientiarum. Technology
organic material, once the starting periods without
inoculation are quite long (FREIRE et al., 2008).
Indigo blue dye
The dye used with the wastewater was the
synthetic Blue Indigo, purchased at specialized
commerce. After an adaptation period of the
biomass to the new conditions (30 days), the dye
was added to the affluent solution of the UASB
reactor in the concentration of 300 mg L-1. The
indigo dye concentration and the ratio between the
applied concentration and the respective value of
color were determined in preliminary tests and
literature review.
Adsorbent materials
As adsorbent materials, in the present study were
used, the activated carbon (testimony material) and
the pottery clay (building industry material). The
activated carbon is a material employed widely in
adsorption processes of several classes of dyes. Its
viability not only as an effective adsorbent, but also
as a support media of biological reactors, mainly of
fluidized bed reactors, is systematically presented in
literature.
In general are used coals of vegetable origin,
being activated with CO2, water vapor or phosphoric
acid.
The vegetable coal, for example, is obtained from
the burning of wood, an activity that implies in
environmental degradation, and the search for
alternative adsorbent materials, derived from less
aggressive activities, becomes a need of researches
related to the subject.
Certainly, the choice of pottery clay as an
adsorbent material obeyed to a more speculative
character. By the fact of the clay in its different
forms (bentonite, vermiculite, illite, among others)
is a material with proved adsorbent potential, it is
assumed that the pottery, for being formed from the
burning of clay at 600ºC also manifest such
characteristics.
Thus, the parcel of the building industry rubble
formed by this material (mainly bricks, ceramic tiles
and roof tiles) can be reused in adsorption
operations.
Experimental procedure
Initially, the synthetic wastewater was prepared
to present COD of about 500 mg L-1. The synthetic
textile effluent was stored in a 50 liter-container and
transported to the UASB reactor through solenoid
dosing pump (Prominent). The reactor feeding was
initially performed with extremely reduced
flowrates, aiming the adaptation of the biomass
Maringá, v. 35, n. 1, p. 53-58, Jan.-Mar., 2013
56
Acta Scientiarum. Technology
Results and discussion
UASB reactor performance
COD (mg L-1)
The monitoring results of the reactor performance
on the removal and the removal efficiency of COD are
illustrated in Figures 2 and 3, respectively.
Time (days)
Figure 2. Temporal variation of influent and effluent COD
values in the UASB.
COD removal efficiency (%)
(inoculum sludge) to the provided substrate.
After passing through the UASB, the wastewater
was collected in an output reservoir.
During the first days, only the UASB reactor was
put into operation. This strategy is due to distinct
reasons. The idea is that, besides respecting the time
limits of biomass adaptation to the synthetic
wastewater, the input parameters should be varied in
such a way to reach more optimized operational
conditions.
Also, the physical operations and the chemical
processes of treatment usually present much faster
responses than the biological processes, not
requiring in this way, the same time of operation.
Completed the period of the UASB operational
optimization, a volume of the reactor effluent was
accumulated for the conduction of the tests in the
adsorption unit.
The adsorption tests were performed in “Jar test”
equipment (Nova Ética, model 218-6LDB), capable
of 6 simultaneous tests. The two adsorbent materials
used (activated carbon and pottery clay) were
selected by the sieving, particles with about 2 mm of
diameter.
Before the tests, the activated carbon was oven
dried at 60 ± 2°C for 12h and the pottery clay for
24h at 103 ± 2ºC. Both the analyzed adsorbents
were submitted to an effluent with the same
characteristics to obtain greater reproducibility of
the results.
For each adsorbent, four simultaneous batch
tests were performed for the pre-determined masses
of 70, 100, 150 and 200 g of adsorbent in contact
with 1 liter of effluent in each container.
The jars (2.5 liters capacity) were submitted to a
constant rotation speed of 120 rpm and the total test
duration of 6h. Aliquots of the effluent were
withdrawn every 120 minutes (stirring switched off
temporarily) for the reading of color removal.
The samples of each container were centrifuged
for 5 minutes at 2500 rpm in centrifuge MTD III
PLUS to separate the solid part of the supernatant.
For the color removal estimation, readings of initial
and final absorbance were performed in the UASB
reactor and in the adsorption tests in a
spectrophotometer 600 PLUS – FEMTO with
wavelength of 560 nm.
All the analyses were performed at the Pollution
and Sanitation Laboratory of the DTC/UEM. The
methodologies of analyses and the procedures for
collection and preservation of samples followed the
patterns described in the Standard Methods for the
Examination of Water and Wastewater (APHA;
AWWA;WEF, 2005).
Conceição et al.
Time (days)
Figure 3. COD removal efficiency in the UASB reactor.
In the period of the UASB reactor operation
that treats the synthetic textile effluent, it was
obtained mean affluent COD of 461.24 mg L-1
with standard deviation of 88.51 mg L-1, obtaining
input values of COD similar to the initial values
stipulated (500 mg L-1). The mean effluent COD for
the same period was 88.41 mg L-1, showing
considerable removal of the organic matter (Figure 2).
Analyzing the Figure 3, it was verified that the
mean removal efficiency of COD in the UASB
throughout the observation period was 81.2%, with
peaks up to 96.4%.
In the Figures 4, 5 and 6 are presented the values
of pH, alkalinity and volatile acids, respectively,
obtained from the reactor performance monitoring.
The mean values of affluent and effluent pH in
the UASB reactor (Figure 4) were 7.6 and 8.0,
respectively, indicating the consumption of acids
and alkalinity generation in the biochemical
reactions inside the UASB.
Maringá, v. 35, n. 1, p. 53-58, Jan.-Mar., 2013
Treatment of textile effluent by adsorption
57
adsorbent, in the masses of 70, 100, 150 and 200 g
are presented in Table 2.
pH
Table 2. Absorbance values and final efficiency of color removal
obtained in the adsorption test, using activated carbon for the
masses of 70, 100, 150 and 200 g.
Time (min.)
0
120
240
360
Ef. (%)
M1 70 g
0.249
0.011
0.004
0.003
99.0
M2 100 g
0.249
0.012
0.008
0.001
99.6
M3 150 g
0.249
0.011
0.003
0.001
99.6
M4 200 g
0.249
0.003
0.002
0.001
99.6
Time (days)
Volatile acids (mg L-1)
Figure 5. Temporal variation of influent and effluent values of
partial alkalinity of the UASB.
Color removal (%)
Time (days)
The results in the Table 2 pointed out that the
activated carbon used in the adsorption tests
presented great efficiency in the removal of the Blue
Indigo dye for the four masses analyzed of
adsorbent. The efficiencies obtained for the masses
of 70, 100, 150 and 200 g were 99.0, 99.6, 99.6 and
99.6%, respectively.
For the three last masses of analyzed carbon, it
was obtained the same values of color removal
(Figure 7), indicating removal stabilization by using
100 g of the adsorbent.
Activated carbon mass (g)
Partial alkalinity (mg L-1)
Figure 4. Temporal variation of influent and effluent pH values
of the UASB.
Samples
Activated carbon mass (g)
Color removal (%)
Figure 7. Color removal using activated carbon for the masses of
70, 100, 150 and 200 g.
Pottery Clay
Time (days)
Figure 6. Temporal variation of influent and effluent volatile
acids values of the UASB.
The alkalinity generation throughout the
anaerobic process is a good indicative of stability.
The higher values in the effluent (mean value of 307
± 23 mg L-1) than in the affluent (225 ± 56 mg L-1)
represented the efficiency in the removal of volatile
acids from the system.
Adsorption units performance
Activated carbon
The data obtained by means of the readings of
color removal, and the final efficiency of removal for
the adsorption tests using the activated carbon as
Acta Scientiarum. Technology
The Table 3 lists the absorbance results obtained
with the adsorption tests in pottery clay and the final
efficiency of color removal for the four masses
analyzed.
The color removal using different masses of
ceramic clay is shown in the Figure 8.
Analyzing the data of the Table 3 and Figure 8, it
was observed that the largest amounts of clay have
also provided higher efficiencies, being the highest
(97%) obtained from the test with 200 g.
A shortcoming verified in these tests was the
detachment of material from the adsorbent to the
solution, material that even after centrifugation was
not completely removed, undermining the
absorbance readings, being performed previous
washing of adsorbent (before the drying), to eliminate
the finest particles, minimizing this problem.
Maringá, v. 35, n. 1, p. 53-58, Jan.-Mar., 2013
58
Conceição et al.
Table 3. Absorbance values and final efficiency of color removal
obtained in the adsorption test using pottery clay for the masses
of 70, 100, 150 and 200 g.
M1 70 g
0.222
0.167
0.128
0.097
56
M2 100 g
0.222
0.130
0.119
0.073
67
M3 150 g
0.222
0.153
0.062
0.041
82
M4 200 g
0.222
0.128
0.075
0.006
97
Color removal (%)
Pottery clay mass (g)
Time (min.)
0
120
240
360
Ef. (%)
Samples
Pottery clay mass (g)
Color removal (%)
Figure 8. Color removal using pottery clay for the masses of 70,
100, 150 and 200 g.
Conclusion
The mean efficiencies of COD and color
removal were 81.2 and 69%, respectively. The
reactor presented stability, even with increasing
flowrate and dye concentration.
The activated carbon and the pottery clay
removed 99.6 and 97.0% of color, respectively, for
200 g of adsorbent.
Greater amount of adsorbent masses in the batch
tests promoted higher efficiencies of color removal.
The results indicated the potential of the pottery
clay as adsorbent under the studied conditions,
representing an alternative for its adequate disposal,
with benefits for the field of effluents treatment.
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Received on April 6, 2011.
Accepted on December 5, 2011.
License information: This is an open-access article distributed under the terms of the
Creative Commons Attribution License, which permits unrestricted use, distribution,
and reproduction in any medium, provided the original work is properly cited.
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