Effect of aeration then granular activated carbon on

International Journal of Computation and Applied Sciences IJOCAAS, Volume 3, Issue 2, October 2017, ISSN: 2399-4509
Effect of aeration then granular activated carbon
on removal efficiency of TOC, COD and
Coliform, Fecal coliform for “Sorkheh Hesar
Canal" water
Amerah A. Radhi and Mahdi Borghei

Abstract—This study describes an experiment in which
aeration and granular activated carbon (GAC) have been used
for removal of dissolved organic matter, bacteria from river
water. River water samples were collected from "Sorkheh Hesar
Canal" east Tehran, Iran and subjected to aeration process then
to granular carbon activated. The aeration process has been
continuously effective during 24 hours followed by granular
carbon activated filter during the treatment process. The sample
treated water was taken to determine of chemical oxygen demand
(COD), total organic carbon and coliform, fecal coliform tests.
the spectrophotometer has been used in the laboratory
experience for measure COD, total organic carbon analyzer for
measure TOC and method total coliform bacteria (TC) for
measure
coliform, fecal coliform. The efficiency of this
experiment has been investigated in the removal COD, TOC and
coliform, fecal coliform significantly decreased as it reached to
77.5, 76.6, 56.7, 56.7% respectively.
Index Terms— Sorkheh Hesar Canal, aeration, granular
activated carbon, organic matter.
w
I. INTRODUCTION
ater is the lifeblood of the first life, so there are no
human, plant or animal without it [1]. Although water
occupies more than 80 percent of the earth area, drinking
water is only 1 percent of it [2]. The distillation and filtering
of water from dirt, impurities, microbes, and algae is very
important to make it fit for human use [3]. Water distillation
and distillation processes take high energy consumption, and
therefore consume fossil fuels for this purpose [4]. The
consumption of fossil fuels causes major environmental
problems. The consumption of this volatile fuel is also a threat
to national economic security [5]. The shift to the use of
renewable and alternative energies for fossil fuels to produce
potable water is very important [6, 7]. Solar energy can be
Corresponding Author: Amerah A. Radhi, Energy and Renewable Energies
Technology Center, University of Technology, Baghdad, Iraq.
(e-mall: amera1312@yahoo.com).
Dr. Mahdi Borghei, professor of Department Chemical and Petroleum
Engineering, Sharif University of Technology, Tehran, Iran.
(e-mail: mbroghei@sharif.edu).
considered an excellent alternative to water production and
distillation and has been used for thousands of years to obtain
potable water [8, 9, and 10].
Water quality observation is a main tool in the administration
of freshwater resources, allowing the identification of sources
of pollution, which can help maintain pollution resources free from microorganisms and chemicals [11]. As indicators
which representing the level of organic matter, biochemical
oxygen demand (BOD) and chemical oxygen demand (COD)
have been used mainly. Total organic carbon (TOC) is the
most important parameter for measuring organic pollution in
water [12-13].
The method of chemical oxygen demand
(COD) you need (a few hours) to complete compared with
BOD test [14-18]. In comparison, TOC measurement can be
treated more quickly, without the need for large quantities of
reagents. This is possible because the TOC analysis is done
by measuring carbon dioxide resulting from the direct
oxidation of the organics [19]. Total organic carbon (TOC) is
generally derived from decaying vegetation, bacterial growth,
and metabolic activities of living organisms [20]. The
chemical oxygen demand (COD) test is usually used to
measure the amount of organic compounds in water [21].
COD, TOC reduction is the most important parameter when
evaluating filter performance in water treatment. COD, TOC
is the most significant contaminant in surface water.
Therefore, its effective reduction is particular importance [22,
23]. Aeration is a process that collects water and air in closed
contact, these processes, which use dissolved oxygen, help to
make the waste harmless, break organic waste into simple
substances to make it a food for bacteria [24]. Operations by
aeration lead to effective removal of the unwanted gas and
remove many organic pollutants such as hydrocarbons, some
pesticides and halogenated organic compounds [25]. Activated
carbon is a solid substance Non-porous, it consists of wide
layers of graphite and has a high surface area; It has been
treated in special ways to make it porous. It has a high ability
to adsorb gases and toxins, especially micro-organic pollutants
from water in addition to the removal of other background
organic compounds measured as total organic carbon [26-28].
It is also used to purify contaminated water and wastewater,
also used to kill bacteria and improves taste, odor and color
associated with organic matter found in water. Carbon consists
of a positive charge and is designed to attract negatively
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charged water pollutants [27, 29, 30]. Activated carbon has
two types powdered or granular. Granular activated carbon
(GAC) is used in dedicated columns in the form of a filter
[31]. In Europe and North America, the use of granular
activated carbon is common seeking to remove micropollutants from drinking water [32]. Activated carbon
adsorption is one of the recommended processes for removal
of byproducts precursor decontamination, organic micropollutants, and compounds that transmit taste and odor to
drinking water [33]. It has been activated in special ways to
obtain a large surface area (500-1500 g/m2) and almost one
gram of activated carbon has a surface area in excess of 3,000
m2. Activated carbon particle consists of particles of the size
of each of them about one millimeter - ie, greater than 10 to
100 times of the powder granules and typical particle sizes
that can be removed by carbon filters range from 0.5 to 50 μm
[28]. Activated coal is used as an absorbent material for
organic and non-polar materials, as well as in the treatment of
gases and water. It is the most used substance as a sorbent for
gases. Furthermore, it seems very effective for the removal a
wide groups of artificial volatile organic [34-37]. The
Objective of this research was to assess the effect of aeration
and granular activated carbon filter for reducing of water
contaminants content to find the effective treatment process of
“Sorkheh Hesar Canal” water. Physical & chemical properties
of water were measured before and after treatment and these
water parameter tested were: Chemical Oxygen Demand
(COD), Total Organic Carbon (TOC) and Coliform and fecal
coliform.
Figure (1): Map of Tehran City illustrates the study sites on Sorkheh Hesar
Canal
C. Specification of GAC used in the laboratory
II. MATERIALS AND METHODS
Specifications
A. Study Area
This study was conducted in Sorkheh Hesar canal during
August 2015, which is situated in east of Tehran. This canal
runs from Alborz Mountains, through districts of 7, 14 and 20
of Tehran municipality within the city limits which also
named as "Abazar Canal" (as Figure 1). Water from Alborz
Mountain, flow through this canal which collects rain water
and surface waters. During the course of water flow, sewage
and polluted water run into the canal causing wide spread
contamination.
B. Sampling
Water samples were collected from Sorkheh Hesar
Canal water in east Tehran at varying times. Where they were
collected in plastic bottles and transferred to the laboratory.
The parameters have been measured such as chemical oxygen
demand (COD), total organic carbon (TOC) and coliform,
fecal coliform. These parameters have been selected for their
spread in sewage and industrial water. Samples were analyzed
subsequently for determination physical and chemical
variables.
Identity
conforms
Substances soluble in nitric acid
≤5%
Chloride (Cl)
≤ 200 ppm
Cyano compounds (CN)
passes test
Pb (Lead)
≤ 20 ppm
Zn (Zinc)
≤ 100 ppm
Polycyclic aromates
passes test
Tar products
passes test
n-Hexane adsorption
≥ 30 %
Residue on ignition (600 °C)
≤8%
Loss on drying
≤ 10 %
D. Experimental work
The raw water was treated through aeration then granular
activated carbon filter as soon as it arrived at the lab. The
laboratory system consists of the aeration reactor, it consists of
a rectangular tank 70 cm length and 40 cm wide, at the bottom
of tank there is a slot Through which comes out the water
treated by aeration to the granular activated carbon filter. In
this process, activated carbon is used to remove dissolved
organic matter and bacteria. The water is passed through a
filter containing the carbon medium. When water is allowed to
flow through a filter at a slow rate, contaminants are exposed
to filtration medium for a longer period of time. Activated
carbon absorbs dissolved organic matter and bacteria found in
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contaminated water. The filter consists of a length of 60 cm,
diameter of 5 cm, activated carbon granules occupy 50 cm of
the original length of the column and at the bottom of filter
there is a slot, where treated water is collected as shown in
Figure 2. Physical and chemical tests are performed on treated
water. Basic parameters such as total organic carbon (TOC),
chemical oxygen demand (COD), coliform and fecal coliform
contents were measured according to methods used of test
water and wastewater [38].
R% =
(Ci −Cf)
Ci
∗ 100
(1)
Where, Ci = initial concentration, Cf = final concentration, for
each COD, TOC and coliform, fecal coliform before and after
treatment. The parameters measured for “Sorkheh Hesar
Canal” before treatment shown in Table I.
TABLE I
SUMMARIZES THE MEASURED PARAMETERS FOR “SORKHEH HESAR CANAL”
WATER BEFORE TREATMENT
Parameters
Average value
COD
43 mg/L
TOC
20 mg/L
Total coliform
M.P.N/100ml > 1600
Total fecal coliform
M.P.N/100ml > 1600
III. RESULTS AND DISCUSSION
A. Total organic carbon (TOC)
Figure (2): Planned Methodology & Experimental set-up
E. Analysis
•
Chemical oxygen demand: - is an inexpensive and quick
way, used widely to determine the amount of organic
pollutants present in surface water or wastewater which are
subject to oxidation by strong chemical oxidation, making
COD a useful measure of water quality. This is expressed in
milligrams per liter (mg / L).
COD removal was measured by using spectrophotometer
wavelength (420nm) is manufactured by UNICO America,
model UV-2100. Moreover, hot COD meter HACH model
DRB 200 used in Sharif University of Technology/ Iran.
• Total organic carbon: - In order to determine TOC, total
organic carbon analyzer by manufactured Australia (S.G.E)
model ANA TOC used in Sharif University of Technology/
Iran.
•
Total coliform bacteria (TC):-This examination is
performed for the purpose of detecting coliform bacteria group
in water. Multi-pipe method is used because analysis depends
on small sample they are taken from a large sample, all
methods depend on the rules of statistical (Most
probable number (M.P.N)) and it is considered one of the
oldest methods used. The bacteria were tested in the biological
laboratory at Sharif University of Technology / Iran. The
removal efficiency (% Removal) was calculated from the
following equation:
The results showed that aeration and granular activated
carbon filter was more effective for removal of TOC from the
Sorkheh Hesar Canal water. The reduction in content TOC
was from 20 mg/l in raw water to 2.27 mg/l in treated water
with a mean removal efficiency of 76.6 %. The principle of
absorption requires water to come in contact with the granular
activated carbon and increased contact time also increases the
TOC removal. The higher removal efficiency of TOC is
observed at 110 Days in this study. Water is pumped from
aeration into a column which contains granular activated
carbon; the water comes out through the column constantly,
which gives an accumulation of substances on the filter.
Processes involve the transfer of the pollutant from the water
to the carbon. During certain periods of 10, 30, 50, 70, 90 and
110 Days, the removal efficiency of TOC was 24, 18.7, 34.7,
31.5, 60.3, 76.6 % respectively. Increasing time after 90 Day
resulted in significant improvement in TOC removal
efficiency. Also, this work has shown that the removal of
TOC by aeration then granular activated carbon filter appears
to reach up to removal efficiency of 76.6 % at time 110 Day as
shown in the Figure 3. Therefore the removal here does not
indicate a complete degradation of organic matter. The study
results agree with those of previous studies [39-41] that
examined the performance of granular activated carbon in
removal of organic matter.
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C.
Figure (3): Effect of aeration then granular activated carbon filter on (IN,
OUT, Removal) Total organic carbon
B.
Chemical oxygen demand (COD)
The results showed that aeration and granular activated
carbon filter was more effective for removal of COD from the
Sorkheh Hesar Canal water. The reduction in COD content
was from 43 mg/l in raw water to 4 mg/l in treated water with
a mean removal efficiency of 77.5 %. The principle of
absorption requires water to come in contact with the granular
activated carbon. And increased contact time also increases
the COD removal. The higher removal efficiency of COD is
observed at 110 Days in this study. Water is pumped from
aeration into a column which contains granular activated
carbon; the water comes out through the column constantly,
which gives an accumulation for materials in the filter.
Processes involve the transfer of the pollutant from the water
to the carbon. During certain periods of 10, 30, 50, 70, 90 and
110 Days, the removal efficiency of COD was 36, 37.8, 46,
58, 72.7, 77.5% respectively. Increasing the aeration then
granular activated carbon filter time after 70 Day resulted in
significant improvement in COD removal efficiency.
Total Coliform and Fecal coliform
Also, this work has shown that the removal of COD by
aeration and granular activated carbon filter appears to reach
up to removal efficiency of 77.5 % at time 110 Day as shown
in the Figure 4. Therefore the removal here does not indicate a
complete degradation of organic matter. The study results
agree with those of previous studies [29-31] that examined the
performance of granular activated carbon in removal of
organic matter.
The results showed that aeration then granular activated
carbon filter was effective for removal of both bacteria from
the Sorkheh Hesar Canal water. Where it has gave both
bacteria the mean removal efficiency of 56.7 % at 110 Day.
Increased contact time also increases the bacteria removal.
Note, increasing adsorption time after 90 Day resulted in
significant improvement in both bacteria removal efficiency
up to 44%. The higher removal efficiency of both bacteria is
observed at 110 Days as shown the Figure 5. Also, this work
has shown that the removal of both bacteria via aeration
follow granular activated carbon filter appears to have good
removal efficiency. It seems very clear that both bacteria
removal efficiency was also similar. The study results agree
with those of previous studies [29-31] that examined the
performance of granular activated carbon in removal of
coliform, fecal coliform.
Figure (5): Effect of aeration then granular activated carbon filter on removal
efficiency coliform, fecal coliform
The study results show the performance of aeration then
granular activated carbon filter on as follows: The highest
removal efficiency was for COD, TOC, and Coliform, Fecal
coliform 77.5, 76.6, 56.7, 56.7% respectively, As Figure 6
manifests.
Figure (4): Effect of aeration then granular activated carbon filter on (IN,
OUT, Removal) Chemical oxygen demand
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Figure (6): Effect of granular activated carbon filter after aeration on removal
efficiency TOC, COD and coliform, fecal coliform
IV. CONCLUSIONS
Finally, it can be concluded that the aeration then the
granular activated carbon process can be considered as a
reliable method, flexible, efficient and economical to river
water treatment. The source of contamination by various
chemicals are generated such as industrial waste as well as
domestic wastewater, which are released to Sorkheh Hesar
Canal that has raised a wide pollution and this in turn sources
great concern because affects human health and the
environment. Based upon the experiment results in this study,
the following observations and conclusions could be drawn:
1-The aeration and granular activated carbon have an
important impression on water and sewages treatment, special
for organic matter and bacteria.
2- The efficiency of the deletion with increasing the contact
time has a direct relationship.
3-where chemical oxygen demand was correlated with total
organic carbon value. However, the decrease of total organic
carbon level leads to lower chemical oxygen demand of
treated water.
4- It also removes coliform and fecal coliform in an acceptable
manner.
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