Journal of Environmental Health and Sustainable Development. 2016; 1(1)
Original Article
Performance Evaluation of Tile Wastewater Treatment with Different
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Coagulants
Tahereh Zarei Mahmoud Abadi 1, Asghar Ebrahimi 2*, Mohammad Taghi Ghaneian 3, Mehdi Mokhtari2, Mohammad
Hossein Salmani4, Parvaneh Talebi 1
1
BSc, Environmental Science &Technology Research Center, Department of Environmental Health Engineering, School of Public
Health, Shahid Sadoughi University of Medical Sciences,Yazd, Iran, [email protected], [email protected]
2
Assistant Professor, Environmental Science &Technology Research Center, Department of Environmental Health Engineering ,
School of Public Health, Shahid Sadoughi University of Medical Sciences,Yazd, Iran, [email protected]
3
Associate Prof. Environmental Science &Technology Research Center, Department of Environmental Health Engineering , School
of Public Health, Shahid Sadoughi University of Medical Sciences,Yazd, Iran, [email protected]
4
Assistant Professor, Environmental Science &Technology Research Center, Department of Environmental Health Engineering,
School of Public Health, Shahid Sadoughi University of Medical Sciences,Yazd, Iran, [email protected]
Received: 18 Jan 2016
Accepted: 29 Feb 2016
Abstract
Introduction: The objective of this study was, wastewater quality investigation and removal efficiency of
contaminants from the wastewater tile factory by using coagulants includes ferric chloride, ferric sulfate and ferrous,
aluminum sulfate and poly aluminum chloride in order to reuse it in the processing line.
Methods: This is an applied study. With regard to shiftwork schedules of the factory, the composite samples of
wasrewater in production line was obtained. Firstly, based on standard methods wastewater parameters were measured .
In the next step by using the jar- test the effect of changing coagulants dosing(0.15, 0.2, 0.25, 0.3, 0.35g/L) and pH
values (7,9,11) on the removal parameters of turbidity, EC, TSS, TS and COD was investigated. Finaly the effective
dose and optimal pH were selected and the best coagulant was determined.
Results:The optimum PH of ferric chloride, ferric sulfate and ferrous that optimum was 11as well as it was 7 for
aluminum sulfate and poly aluminum chloride. The optimum concentration of iron-based coagulants and aluminumbased coagulants was 0.3 g/L and 0.25 g/L, respectively. Poly aluminum chloride with removal of 99.92% , 99.94%,
89.8 and 75% has the best removal efficiency for turbidity, TSS, TS and COD, respectively. In addition, in a lower dose
aluminum sulfate, ferrous sulfate, ferric chloride and ferric sulfate had the best removal efficiency.
Conclusion: Among the five studied coagulants, poly aluminum chloride, aluminum sulfate and ferrous sulfate had
the most efficiency, respectively. Due to the high cost of aluminum chloride, it needs more accuracy to select the most
suitable coagulant.
Keywords: Coagulant, Wastewater treatment, Tile industry, Turbidity, COD
*Corresponding author: Asghar Ebrahimi Email: [email protected] Tel: 09132679641
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Zarei Mahmoud Abadi Tahereh, et al.
Introduction:
be removed just by a simple sedimentation. As a
In recent decades, the growth of consumption and
result, effluent from it can only be returned to the
increasing of industrial production was reflected
ball mill. But have not recycled water quality
in rapid decline of available natural resources (raw
necessary for use in another part especially of the
materials and energy resources). On the other
preparation glazes. As a result, a significant
hand, high quantity of waste generated in which
amount of groundwater is used as the fresh water
most of them not directly recyclable (1). Water is
source in production line for production glaze and
used as an initial material in many industries and
other coatings. However, groundwater supplies is
wastewater is discharged to the environment (2). In
limited. Tile industry should be find solution to
order to achieve conditions for sustainable
decrease its groundwater consumption (5). Water
development, industrial developments align with
recycling and reuse in the consumption cycle not
environmental development is inevitable. Among
only reduce consumption and
the important environmental industrial parks,
efficiency, but not exit wastewater pollutants to
providing the required water industry and entering
surrounding environment as a principle in order to
industrial pollutants into groundwater sources.
prevent contamination of the environment should
Construction of appropriate wastewater treatment
take priority.
systems
the contamination of water
The composition of these tile industry wastewaters
resources and environment and also provide a new
is include clays, frits and insoluble silicates,
source of water for reuse (3). Today, shortage of
electrolytes, anions such as sulfate(100-500 mg/L),
water for both drinking and industrial communities
chloride (100-700mg/L), suspended and dissolved
is a global concern. Therefore, protection of water
heavy metals such as lead and zinc, COD (150-
resources is very important. there are many studies
1000 mg/L) and BOD (50-400 mg/L) (6, 8).
in water minimizing to solve this problem in
Organic materials that mainly come from the
industries with different approaches (4). Water
additives used in decorate the tiles (5). Contrast
management is a very important issue in most
municipal
industrial sections, (5). Water is a very important
methods, mainly to respond. Therefore, different
raw material in the manufacture of tiles and its
methods based on physico-chemical process are
usage varies greatly between sectors and processes
needed. Physical-chemicals treatment methods can
(6). Water consumed for the operation of various
be used for wastewater tile. Physical-chemical
units preparation and cleaning of equipment such
wastewater treatment including homogenization,
as slurry and glaze preparation, glazing lines,
aeration, Sedimentation, filtration, activated carbon
washing gases from scrubbers and etc. Major
adsorption, coagulation and flocculation, ion
wastewater produced in these parts is only due to
exchange and reverse osmosis (9).Now, coagulants
washing (7). A significant amount of suspended
compound of aluminum is very common in water
solids and turbidity in wastewater industries could
and wastewater treatment and the use of these
prevent
23
wastewater
has economic
biological
treatment
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Tile Wastewater Treatment with Different Coagulants
materials increased. In addition, these are materials
and
very cheap and easily accessible. The selection the
efficiency was 90 percent (13). The aim of this
type of coagulation is one the most important
study was to investigate the quality of wastewater
decision for the wastewater treatment and will be
and use of coagulation-flocculation process with
based on the nature of wastewater. Poly aluminum
coagulants ferric chloride, ferric sulfate and
chloride (PAC) has proven to be more efficient in
ferrous, aluminum sulfate and poly aluminum
low dosages and in a wider pH range acts (10).
chloride for suspended solids and turbidity
Nilsalab investigated the use of the coagulation
reduction from wastewater in order to reuse it in
process in the ceramic industry wastewater
the processing line.
Moringa oleifera, that turbidity removal
treatment using aluminum sulfate and reported
most removal efficiency of turbidity at pH 6-7 with
Methods:
optimal dose 200 mg/L(11). In another study
In this study sample was composed of wastewater
fahiminia et al, the effect of different doses of
processing line according to shift work and
coagulants
aluminum
changes taking it. Measuring parameters pH, EC
chloride, Polymer, Ferric chloride (Fecl3) and lime
(multi-parameter model 40HQ company HACH)
on turbidity, total suspended solids and total solids,
and temperature were determined at the spot of
removal were investigated. The results indicated
sampling due to changes over time. Samples were
that lime in dose 25 ppm is the best coagulant for
collected in 20-L plastic containers and transported
turbidity
highest
to the laboratory and stored at 4°C. Experiments
efficiency for TS removal (82.5%) is related to
were carried out according to standard method for
using Alum in dose100 ppm (12). paula et al, in
water and wastewater tests (14). Physical and
2014 studied concrete industry for wastewater
chemical raw wastewater is mentioned in table 1.
including
removal
Alum,
(99.8%)
poly
and
the
treatment using a combination of aluminum sulfate
Table 1: Physical - chemical characteristics, raw wastewater tile industry
Parameters
unit
Min
Max
Average ± SD
pH
-
8.2
8.6
8.3±0.6
Temperature
(°C)
30
32
31±1
EC
(us/cm)
2142
2700
2484±299.57
Turbidity
NTU
9500
13300
11100±1969.77
TDS
(mg/L)
1096
1246
1185.33±79
TSS
(mg/L)
13450
34414
21221.33±11485.45
TS
(mg/L)
14546
35628
22390±11529.71
COD
(mg/L)
151.2
490
361.33±183.66
BOD5
(mg/L)
100.8
392.5
266.51±149.58
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Zarei Mahmoud Abadi Tahereh, et al.
The study was performed in laboratory scale using
Germany. Hydrochloric acid 1 normal and lime Ca
the jar by five coagulant ferric chloride, ferric
(OH)
sulfate and ferrous, aluminum sulfate as metal salts
value
and Poly aluminum Chloride (PAC) as hydrolyzed
processes. Details coagulants used are described in
aluminum salt. This was compounded of Merck
table 2.
2
solution were used for adjusting the pH
of
wastewater
during
the
treatment
Table 2: Characteristics of coagulants used in the study
Coagulants
ferric chloride
ferric sulfate
sulfate ferrous
aluminium sulfate
Poly aluminum Chloride
Formula
Molecular weight (g/mole)
No. Artie
Concentration (%)
Fecl3.6H2O
270.30
3943
10
Fe2(SO4)3.H2O
399.88
3926
10
FeSO4·7H2O
278.02
3965
10
AL2(SO4)2
666.42
1102
10
Al2(OH)nCl6-n
10
The coagulation-flocculation process carried out
minutes at 20 rpm. At the end of slow mixing, was
using a jar test manufactured by HACH (model
considered 30 minutes sedimentation for sample.
402-7790). The samples were after out of the
After the sedimentation period, the supernatant
refrigerator for 2 hours at room temperature, until
wastewater into the beakers extracted using a
temperature reaches to 22°C. The sample was
plastic syringe and Measured parameters turbidity
given 100 minutes sedimentation time. In order to
(turbidity meter TB100 model manufactured by
determine the optimum pH coagulant materials,
Eutech), EC, TSS, TS, COD. Finally, optimal dose
evaluated the different pH (7, 9, 11) in the fixed
each coagulant was determined. To draw the
amount of coagulants (iron-based compounds 0.25
relevant diagrams software Excel 2010 was used.
g/L and aluminum-based compounds 0.2 g/L). By
In this research, in order to increase the accuracy
measuring parameters turbidity, EC, TSS, TS,
of experiments, all experiments were repeated
COD for each pH, a sample with the highest
twice and the mean values were reported as the
removal efficiency for the desired parameters, pH
final result.
of the sample as optimum pH was considered.
Results:
Then wastewater pH regulation at the optimum
Figure 1 shows the efficiency of turbidity removal
value and Followed by various amounts of
during the sedimentation, before coagulation
coagulants materials (0.15, 0.2, 0.25, 0.3, 0.35 g/L)
process. According to this figure, sedimentation
simultaneously added to the wastewater to the
different times were tested on the tile raw
volume of one liter and it was determined the
wastewater
optimal amount. Wastewater and coagulants were
sedimentation time of 100 minutes, the turbidity of
stirred at room temperature first with rapid mixing
wastewater from 10500 to 6310 NTU decreased
for 1 min at 100 rpm and slowly mixing for 10
(39.9% of turbidity removal efficiency). Turbidity
25
before
adding
coagulants.
The
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Tile Wastewater Treatment with Different Coagulants
removal efficiency almost unchanged after 100
COD. In the case of ferric sulfate results the effect
minutes. Figures 2 to 6 show the results optimum
of different doses indicate that the rate removal the
pH about coagulants used. Ferric chloride has been
studied parameters at doses consumption greater
effective in alkaline pH, by doing a jar test for each
than 0.3 g/L trends has been fixed and rate removal
sample three pH, the optimum pH of 11 was
of turbidity, EC, TSS, TS respectively 99.69,
obtained. The results showed that the optimum pH
22.45, 99.71, 90.27 Percentage and 72.5% removal
of ferric sulfate and ferrous the most appropriate
of COD. The results of experiment ferrous sulfate
pH obtained, is equal to 11. The results of the
coagulant showed in dosage 0.3 g/L have worked
experiments of coagulant aluminum sulfate and
well in removing contaminants and rate removal of
poly aluminum chloride showed the optimum pH
turbidity, EC, TSS, TS in order
ord 99.9, 26.47, 99.9,
for these two coagulants is 7. For the investigation
investigat
90.9 Percentage and 60% removal of COD. The
the effect of different dosages of coagulants to
results the effect of different doses aluminum
remove contaminants by ferric chloride, ferric
sulfate and Poly aluminum chloride indicate that
sulfate and ferrous, aluminum sulfate and poly
removed studied parameters the dosage 0.25 g/L
aluminum chloride at pH fixed at doses (0.15, 0.2,
then for both coagulation trend has been fixed. The
0.25, 0.3, 0.35 g/L),
), Jar tests were performed.
result dose 0.25 g/L was selected as the optimal
Figures 7 to 10 shows the effect of different doses
dose for the two coagulants. The removal of
of coagulant
lant to remove contaminants. The results
turbidity, EC, TSS, TS and COD for aluminum
of the experiment ferric chloride coagulant showed
sulfate, respectively 99.88,, 24.95, 99.86, 90.68 and
that in dosage 0.3 g/L works well in the removal of
60 Percentage. For poly aluminum chloride
the evaluated parameters and rate removal of
respectively 99.92, 17.74
74, 99.93, 89.86 and 75
turbidity, EC, TSS, TS respectively 99.84, 20.46,
percentage.
99.83, 90.09 Percentage and 50% removal of
Figure 1: Effect of sedimentation, before coagulation process for the removal of turbidity
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Tahereh Zarei Mahmoud Abadi, et al.
Figure 2: Effect of coagulants on turbidity removal efficiency at different pH
Figure 3: Effect of coagulants on electrical conductivity removal efficiency at different pH
Figure 4: Effect of coagulants on total suspended solids removal efficiency at different pH
27
Figure 5: Effect of coagulants on total solids removal efficiency at different pH
Figure 6: Effect of coagulants on COD removal efficiency at different pH
100
Turbidity Removal (%)
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Tile Wastewater Treatment with Different Coagulants
ferric chloride
99.8
ferric sulfate
99.6
ferrous sulfate
99.4
aluminium sulfate
99.2
PAC
99
0
0.1
0.2
0.3
0.4
Coagulant dosage(g/l)
Figure 7: The effect of coagulant dosage on turbidity removal efficiency
28
Figure 8: The effect of coagulant dosage on total suspended solids removal efficiency
35
EC Removal (%)
30
ferric chloride
25
ferric sulfate
20
ferrous sulfate
15
aluminium sulfate
PAC
10
5
0
0.1
0
0.2
0.3
0.4
Dosage(g/l)
Figure 9: The effect of coagulant dosage on electrical conductivity removal efficiency
91
90.5
TS Removal(%)
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Tahereh Zarei Mahmoud Abadi, et al.
ferric chloride
ferric sulfate
90
ferrous sulfate
aluminium sulfate
PAC
89.5
89
0
0.1
0.2
0.3
0.4
Dosage(g/l)
Figure 10: The effect of coagulant dosage on total solids removal efficiency
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Tile Wastewater Treatment with Different Coagulants
80
COD Removal (%)
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70
60
50
ferric chloride
40
ferric sulfate
30
ferrous sulfate
20
aluminium sulfate
10
PAC
0
0
0.1
0.2
0.3
0.4
Coagulant dosage(g/l)
Figure 11: The effect of coagulant dosage on COD removal efficiency
Discussion:
0.5 g/L turbidity removal 99.4 percentage while in
According to figure 1, sedimentation time of 100
this study despite the turbidity 16 times more ferric
minutes was selected as the best time remained
chloride at dose 0.3 g/L Shown more efficiency for
before the coagulation process. The results research
turbidity (99.84%). In the study Paula (13) despite
showed that aluminum sulfate and PAC better
the combination of aluminum sulfate with other
performance at pH 7. The important reason for such
coagulants removal efficiency had 90% while this
behavior is: 1- at low pH, Presence monomers
study only aluminum sulfate, have been able to
particles, aluminum causing neutralization of
remove 99.88% for turbidity. COD removal rate
anionic particles contaminants and sedimentation of
increased with increasing coagulants.These findings
doing better. 2- at low pH, concentration of
show that for remove significant COD, required
dissolved aluminum decreased with decreasing the
high doses of coagulants. This could be due to the
Al
(OH)4-
and reduce this ratio lead to the
presence of large amounts of organic matter in
sedimentation process improvement and this anionic
effluent and their reaction is with coagulants that
aluminum hydroxide reducing the effects of
causes the suspended matter in effluent oxidized,
coagulation (10). But at alkaline pH due to the
signed and eliminate this process can reduce
formation of fine flocs, less sedimentation and also
wastewater COD (15). The results showed the
decrease efficiency. Coagulants aluminum sulfate
electrical conductivity increases by increasing
and PAC compared with other coagulants in the
coagulants. Comparison of the effects these
lower dose showed most of the removal efficiency
coagulants to remove contaminants showed poly
of turbidity, TSS, COD. The pH and optimal dose of
aluminum chloride has a better performance
aluminum sulfate were consistent with studies
compared to other coagulants. Poly aluminum
Nilsalab (11). However, in study Mr. Fahiminia (12)
chloride compared with other coagulants such as
with much less turbidity ferric chloride in dosage
aluminum sulfate, ferric chloride, etc. in medium
30
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Tahereh Zarei Mahmoud Abadi, et al.
and high turbidity of better performance. For
for remove turbidity and COD wastewater.
example, requires a lot less due to ionic load charge
- Due to the high turbidity wastewater tiles, this
more, coarse clots, reduces settling time flukes, less
method has a high potential for practical
sludge production, without the need to regulate the
application in wastewater with high COD and
pH, its better performance at lower temperatures. In
turbidity.
recent years, poly aluminum chloride is used widely
-Having regard to the high efficiency of this method
as an alternative to the traditional aluminum sulfate
and inexpensive and does not require advanced
and
technology as a solution for wastewater treatment
ferric
chloride
coagulant.
In
practical
applications showed that PAC coagulant effect
producing line factories tile is recommended.
produced 2-3 times better than are conventional
aluminum salts (16). According to consumption less
Acknowledgments:
in the same terms such the initial turbidity and
The support President of the School of Public
suspended solids and etc, using a PAC the ultimate
Health and laboratory experts which provide
cost is more economical.
laboratory the possibility to carry out the research
Conclusion:
to be provided and their valuable guidance in this
-Coagulation and flocculation is a suitable method
study helped us to appreciate.
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