performance evaluation of tile wastewater...

Journal of Environmental Health and Sustainable Development. 2016; 1(1)

22

Original Article

Performance Evaluation of Tile Wastewater Treatment with Different

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 aluminum-

based 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

Zarei Mahmoud Abadi Tahereh, et al.

23

Introduction: In recent decades, the growth of consumption and

increasing of industrial production was reflected

in rapid decline of available natural resources (raw

materials and energy resources). On the other

hand, high quantity of waste generated in which

most of them not directly recyclable (1). Water is

used as an initial material in many industries and

wastewater is discharged to the environment (2). In

order to achieve conditions for sustainable

development, industrial developments align with

environmental development is inevitable. Among

the important environmental industrial parks,

providing the required water industry and entering

industrial pollutants into groundwater sources.

Construction of appropriate wastewater treatment

systems prevent the contamination of water

resources and environment and also provide a new

source of water for reuse (3). Today, shortage of

water for both drinking and industrial communities

is a global concern. Therefore, protection of water

resources is very important. there are many studies

in water minimizing to solve this problem in

industries with different approaches (4). Water

management is a very important issue in most

industrial sections, (5). Water is a very important

raw material in the manufacture of tiles and its

usage varies greatly between sectors and processes

(6). Water consumed for the operation of various

units preparation and cleaning of equipment such

as slurry and glaze preparation, glazing lines,

washing gases from scrubbers and etc. Major

wastewater produced in these parts is only due to

washing (7). A significant amount of suspended

solids and turbidity in wastewater industries could

be removed just by a simple sedimentation. As a

result, effluent from it can only be returned to the

ball mill. But have not recycled water quality

necessary for use in another part especially of the

preparation glazes. As a result, a significant

amount of groundwater is used as the fresh water

source in production line for production glaze and

other coatings. However, groundwater supplies is

limited. Tile industry should be find solution to

decrease its groundwater consumption (5). Water

recycling and reuse in the consumption cycle not

only reduce consumption and has economic

efficiency, but not exit wastewater pollutants to

surrounding environment as a principle in order to

prevent contamination of the environment should

take priority.

The composition of these tile industry wastewaters

is include clays, frits and insoluble silicates,

electrolytes, anions such as sulfate(100-500 mg/L),

chloride (100-700mg/L), suspended and dissolved

heavy metals such as lead and zinc, COD (150-

1000 mg/L) and BOD (50-400 mg/L) (6, 8).

Organic materials that mainly come from the

additives used in decorate the tiles (5). Contrast

municipal wastewater biological treatment

methods, mainly to respond. Therefore, different

methods based on physico-chemical process are

needed. Physical-chemicals treatment methods can

be used for wastewater tile. Physical-chemical

wastewater treatment including homogenization,

aeration, Sedimentation, filtration, activated carbon

adsorption, coagulation and flocculation, ion

exchange and reverse osmosis (9).Now, coagulants

compound of aluminum is very common in water

and wastewater treatment and the use of these

Tile Wastewater Treatment with Different Coagulants

24

materials increased. In addition, these are materials

very cheap and easily accessible. The selection the

type of coagulation is one the most important

decision for the wastewater treatment and will be

based on the nature of wastewater. Poly aluminum

chloride (PAC) has proven to be more efficient in

low dosages and in a wider pH range acts (10).

Nilsalab investigated the use of the coagulation

process in the ceramic industry wastewater

treatment using aluminum sulfate and reported

most removal efficiency of turbidity at pH 6-7 with

optimal dose 200 mg/L(11). In another study

fahiminia et al, the effect of different doses of

coagulants including Alum, poly aluminum

chloride, Polymer, Ferric chloride (Fecl3) and lime

on turbidity, total suspended solids and total solids,

removal were investigated. The results indicated

that lime in dose 25 ppm is the best coagulant for

turbidity removal (99.8%) and the highest

efficiency for TS removal (82.5%) is related to

using Alum in dose100 ppm (12). paula et al, in

2014 studied concrete industry for wastewater

treatment using a combination of aluminum sulfate

and Moringa oleifera, that turbidity removal

efficiency was 90 percent (13). The aim of this

study was to investigate the quality of wastewater

and use of coagulation-flocculation process with

coagulants ferric chloride, ferric sulfate and

ferrous, aluminum sulfate and poly aluminum

chloride for suspended solids and turbidity

reduction from wastewater in order to reuse it in

the processing line.

Methods:

In this study sample was composed of wastewater

processing line according to shift work and

changes taking it. Measuring parameters pH, EC

(multi-parameter model 40HQ company HACH)

and temperature were determined at the spot of

sampling due to changes over time. Samples were

collected in 20-L plastic containers and transported

to the laboratory and stored at 4°C. Experiments

were carried out according to standard method for

water and wastewater tests (14). Physical and

chemical raw wastewater is mentioned in table 1.

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

Zarei Mahmoud Abadi Tahereh, et al.

25

The study was performed in laboratory scale using

the jar by five coagulant ferric chloride, ferric

sulfate and ferrous, aluminum sulfate as metal salts

and Poly aluminum Chloride (PAC) as hydrolyzed

aluminum salt. This was compounded of Merck

Germany. Hydrochloric acid 1 normal and lime Ca

(OH) 2 solution were used for adjusting the pH

value of wastewater during the treatment

processes. Details coagulants used are described in

table 2.

Table 2: Characteristics of coagulants used in the study

Coagulants Formula Molecular weight (g/mole) No. Artie Concentration (%)

ferric chloride Fecl3.6H2O 270.30 3943 10

ferric sulfate Fe2(SO4)3.H2O 399.88 3926 10

sulfate ferrous FeSO4·7H2O 278.02 3965 10

aluminium sulfate AL2(SO4)2 666.42 1102 10

Poly aluminum Chloride Al 2(OH)nCl6-n 10

The coagulation-flocculation process carried out

using a jar test manufactured by HACH (model

402-7790). The samples were after out of the

refrigerator for 2 hours at room temperature, until

temperature reaches to 22°C. The sample was

given 100 minutes sedimentation time. In order to

determine the optimum pH coagulant materials,

evaluated the different pH (7, 9, 11) in the fixed

amount of coagulants (iron-based compounds 0.25

g/L and aluminum-based compounds 0.2 g/L). By

measuring parameters turbidity, EC, TSS, TS,

COD for each pH, a sample with the highest

removal efficiency for the desired parameters, pH

of the sample as optimum pH was considered.

Then wastewater pH regulation at the optimum

value and Followed by various amounts of

coagulants materials (0.15, 0.2, 0.25, 0.3, 0.35 g/L)

simultaneously added to the wastewater to the

volume of one liter and it was determined the

optimal amount. Wastewater and coagulants were

stirred at room temperature first with rapid mixing

for 1 min at 100 rpm and slowly mixing for 10

minutes at 20 rpm. At the end of slow mixing, was

considered 30 minutes sedimentation for sample.

After the sedimentation period, the supernatant

wastewater into the beakers extracted using a

plastic syringe and Measured parameters turbidity

(turbidity meter TB100 model manufactured by

Eutech), EC, TSS, TS, COD. Finally, optimal dose

each coagulant was determined. To draw the

relevant diagrams software Excel 2010 was used.

In this research, in order to increase the accuracy

of experiments, all experiments were repeated

twice and the mean values were reported as the

final result.

Results: Figure 1 shows the efficiency of turbidity removal

during the sedimentation, before coagulation

process. According to this figure, sedimentation

different times were tested on the tile raw

wastewater before adding coagulants. The

sedimentation time of 100 minutes, the turbidity of

wastewater from 10500 to 6310 NTU decreased

(39.9% of turbidity removal efficiency). Turbidity


removal efficiency almost unchanged after

minutes. Figures 2 to 6 show the results optimum

pH about coagulants used. Ferric chloride has

effective in alkaline pH, by doing a jar test for each

sample three pH, the optimum pH

obtained. The results showed that the optimum pH

of ferric sulfate and ferrous the most appropriate

pH obtained, is equal to 11. The results of the

experiments of coagulant aluminum sulfate and

poly aluminum chloride showed the optimum pH

for these two coagulants is 7. For the investigat

the effect of different dosages of coagulants

remove contaminants by ferric chloride, ferric

sulfate and ferrous, aluminum sulfate and poly

aluminum chloride at pH fixed at doses

0.25, 0.3, 0.35 g/L), Jar tests were performed.

Figures 7 to 10 shows the effect of different doses

of coagulant to remove contaminants. The results

of the experiment ferric chloride coagulant showed

that in dosage 0.3 g/L works well in the removal of

the evaluated parameters and rate removal of

turbidity, EC, TSS, TS respectively

99.83, 90.09 Percentage and 50%

Figure 1: Effect of sedimentation, before coagulation process for the removal of turbidity


26

removal efficiency almost unchanged after 100

show the results optimum

Ferric chloride has been

jar test for each

optimum pH of 11 was

obtained. The results showed that the optimum pH

most appropriate

The results of the

experiments of coagulant aluminum sulfate and

poly aluminum chloride showed the optimum pH

For the investigation

the effect of different dosages of coagulants to

remove contaminants by ferric chloride, ferric

sulfate and ferrous, aluminum sulfate and poly

aluminum chloride at pH fixed at doses (0.15, 0.2,

), Jar tests were performed.

shows the effect of different doses

lant to remove contaminants. The results

of the experiment ferric chloride coagulant showed

works well in the removal of

the evaluated parameters and rate removal of

TS respectively 99.84, 20.46,

50% removal of

COD. In the case of ferric sulfate results the effect

of different doses indicate that the rate removal the

studied parameters at doses consumption greater

than 0.3 g/L trends has been fixed and rate removal

of turbidity, EC, TSS, TS respectively

22.45, 99.71, 90.27 Percentage and

of COD. The results of experiment ferrous sulfate

coagulant showed in dosage

well in removing contaminants and rate

turbidity, EC, TSS, TS in ord

90.9 Percentage and 60%

results the effect of different doses aluminum

sulfate and Poly aluminum chloride indicate that

removed studied parameters

then for both coagulation trend has been fixed.

result dose 0.25 g/L was selected as the optimal

dose for the two coagulants.

turbidity, EC, TSS, TS and COD for aluminum

sulfate, respectively 99.88,

60 Percentage. For poly aluminum chloride

respectively 99.92, 17.74

percentage.

Effect of sedimentation, before coagulation process for the removal of turbidity

COD. In the case of ferric sulfate results the effect

of different doses indicate that the rate removal the

studied parameters at doses consumption greater

has been fixed and rate removal

TS respectively 99.69,

Percentage and 72.5% removal

of COD. The results of experiment ferrous sulfate

coagulant showed in dosage 0.3 g/L have worked

well in removing contaminants and rate removal of

turbidity, EC, TSS, TS in order 99.9, 26.47, 99.9,

removal of COD. The

results the effect of different doses aluminum

sulfate and Poly aluminum chloride indicate that

removed studied parameters the dosage 0.25 g/L

then for both coagulation trend has been fixed. The

was selected as the optimal

dose for the two coagulants. The removal of

turbidity, EC, TSS, TS and COD for aluminum

, 24.95, 99.86, 90.68 and

For poly aluminum chloride

74, 99.93, 89.86 and 75

Effect of sedimentation, before coagulation process for the removal of turbidity

Tahereh

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

Tahereh Zarei Mahmoud Abadi, et al.

27

Effect of coagulants on turbidity removal efficiency at different pH

Effect of coagulants on electrical conductivity removal efficiency at different pH

Effect of coagulants on total suspended solids removal efficiency at

Effect of coagulants on turbidity removal efficiency at different pH

Effect of coagulants on electrical conductivity removal efficiency at different pH

Effect of coagulants on total suspended solids removal efficiency at different pH


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

Figure 7: The effect of coagulant dosage on turbidity removal efficiency

99

99.2

99.4

99.6

99.8

100

0

Tu

rbid

ity

Re

mo

val

(%)


28

Effect of coagulants on total solids removal efficiency at different pH

Effect of coagulants on COD removal efficiency at different pH

The effect of coagulant dosage on turbidity removal efficiency

0.1 0.2 0.3 0.4

Coagulant dosage(g/l)

ferric chloride

ferric sulfate

ferrous sulfate

aluminium sulfate

PAC

Effect of coagulants on total solids removal efficiency at different pH

Effect of coagulants on COD removal efficiency at different pH

The effect of coagulant dosage on turbidity removal efficiency

aluminium sulfate

Tahereh

Figure 8: The effect of coagulant dosage on total suspended solids removal efficiency

Figure 9: The effect of coagulant dosage on electrical conductivity removal efficienc

Figure 10: The effect of coagulant dosage on total solids removal efficiency

5

10

15

20

25

30

35

0

EC

Re

mo

val(

%)


89

89.5

90

90.5

91

91.5

92

0

TS

R

em

ova

l(%

)


29

The effect of coagulant dosage on total suspended solids removal efficiency

The effect of coagulant dosage on electrical conductivity removal efficienc

The effect of coagulant dosage on total solids removal efficiency

0.2 0.4


ferric chloride

ferric sulfate

ferrous sulfate

aluminium sulfate

PAC

0.1 0.2 0.3 0.4

Coagulante dosage(g/l)

ferric chloride

ferric sulfate

ferrous sulfate

aluminium sulfate

PAC

The effect of coagulant dosage on total suspended solids removal efficiency

The effect of coagulant dosage on electrical conductivity removal efficiency

The effect of coagulant dosage on total solids removal efficiency

ferric chloride

ferrous sulfate

aluminium sulfate

ferric chloride

ferric sulfate

ferrous sulfate

aluminium sulfate


30

Figure 11: The effect of coagulant dosage on COD removal efficiency

Discussion:

According to figure 1, sedimentation time of 100

minutes was selected as the best time remained

before the coagulation process. The results research

showed that aluminum sulfate and PAC better

performance at pH 7. The important reason for such

behavior is: 1- at low pH, Presence monomers

particles, aluminum causing neutralization of

anionic particles contaminants and sedimentation of

doing better. 2- at low pH, concentration of

dissolved aluminum decreased with decreasing the

Al (OH)4- and reduce this ratio lead to the

sedimentation process improvement and this anionic

aluminum hydroxide reducing the effects of

coagulation (10). But at alkaline pH due to the

formation of fine flocs, less sedimentation and also

decrease efficiency. Coagulants aluminum sulfate

and PAC compared with other coagulants in the

lower dose showed most of the removal efficiency

of turbidity, TSS, COD. The pH and optimal dose of

aluminum sulfate were consistent with studies

Nilsalab (11). However, in study Mr. Fahiminia (12)

with much less turbidity ferric chloride in dosage

0.5 g/L turbidity removal 99.4 percentage while in

this study despite the turbidity 16 times more ferric

chloride at dose 0.3 g/L Shown more efficiency for

turbidity (99.84%). In the study Paula (13) despite

the combination of aluminum sulfate with other

coagulants removal efficiency had 90% while this

study only aluminum sulfate, have been able to

remove 99.88% for turbidity. COD removal rate

increased with increasing coagulants.These findings

show that for remove significant COD, required

high doses of coagulants. This could be due to the

presence of large amounts of organic matter in

effluent and their reaction is with coagulants that

causes the suspended matter in effluent oxidized,

signed and eliminate this process can reduce

wastewater COD (15). The results showed the

electrical conductivity increases by increasing

coagulants. Comparison of the effects these

coagulants to remove contaminants showed poly

aluminum chloride has a better performance

compared to other coagulants. Poly aluminum

chloride compared with other coagulants such as

aluminum sulfate, ferric chloride, etc. in medium

0

10

20

30

40

50

60

70

80

0 0.1 0.2 0.3 0.4

CO

D R

em

ova

l (%

)


ferric chloride

ferric sulfate

ferrous sulfate

aluminium sulfate

PAC


31

and high turbidity of better performance. For

example, requires a lot less due to ionic load charge

more, coarse clots, reduces settling time flukes, less

sludge production, without the need to regulate the

pH, its better performance at lower temperatures. In

recent years, poly aluminum chloride is used widely

as an alternative to the traditional aluminum sulfate

and ferric chloride coagulant. In practical

applications showed that PAC coagulant effect

produced 2-3 times better than are conventional

aluminum salts (16). According to consumption less

in the same terms such the initial turbidity and

suspended solids and etc, using a PAC the ultimate

cost is more economical.

Conclusion:

-Coagulation and flocculation is a suitable method

for remove turbidity and COD wastewater.

- Due to the high turbidity wastewater tiles, this

method has a high potential for practical

application in wastewater with high COD and

turbidity.

-Having regard to the high efficiency of this method

and inexpensive and does not require advanced

technology as a solution for wastewater treatment

producing line factories tile is recommended.

Acknowledgments:

The support President of the School of Public

Health and laboratory experts which provide

laboratory the possibility to carry out the research

to be provided and their valuable guidance in this

study helped us to appreciate.

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