Possibility of Reuse of Waste Water in Dairys

7/31/2019 Possibility of Reuse of Waste Water in Dairys

http://slidepdf.com/reader/full/possibility-of-reuse-of-waste-water-in-dairys 1/12

Desalination 195 (2006) 141–152

0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved

*Corresponding author.

Wastewater treatment in dairy industries — possibility of reuse

Baisali Sarkar, P.P. Chakrabarti, A. Vijaykumar, Vijay Kale*

Lipid Science and Technology Division, Indian Institute of Chemical Technology, Hyderabad 500007, India

Tel. +91 (40) 2719-3370; Fax +91 (40) 2719-3370; email: [email protected]

Received 30 June 2005; accepted 7 November 2005

Abstract

The reuse of wastewater from the dairy industry was investigated using coagulation, adsorption and membrane

separation. Dairy industry was chosen as it requires huge volume of water. In recent times, development of newer

membranes with high flux/rejection characteristics have increased the probability of water reuse and recycling up

to a greater extent. In this investigation thorough pretreatment studies were done using different types of coagulants

categorized as inorganic, polymeric, and organic having biological origins. The coagulant treatment was performed

at various pH using different dosages and it was followed by activated charcoal treatment. The combined effects of these two pretreatment methodologies were evaluated. The color and the odor were removed completely and

permanently after charcoal treatment. The pretreated water was passed through a cross flow reverse osmosis

membrane system and the permeate water was found to have very good quality. This was compared to the process

water used by the dairy farm and was found that the water can be recycled or reused.

Keywords: Dairy wastewater; Coagulants; Powdered activated charcoal (PAC); TDS; COD; Membrane processes

1. Introduction

Ever increasing industrialization and rapid

urbanization have considerably increased the rateof water pollution. The dwindling supplies of natural resources of water have made this a serious

constraint for industrial growth and for a reason-able standard of urban living. The environmental

pro-tection agencies have imposed more stringentregulatory prohibitions and they have started more

strict vigil along with some non governmental

organizations to protect the environment. This hasmade the water treatment more expensive and to

comply with the discharge quality standard itself,

is becoming a huge burden for the industries. Itwas therefore felt that the possibilities of reuse of

the wastewater for various purposes should beinvestigated. The recycling or reuse of water for similar duties mainly depends on availability of suitable process technology for water purification.

Due to wide fluctuations in industrial effluentquality, this becomes more challenging. With theadvent of membrane technology and significant



142 B. Sarkar et al. / Desalination 195 (2006) 141–152

improvements in efficiency and cost effectiveness,the competitiveness of recycling over discharge

has greatly increased.

In dairy industries, water has been a key pro-

cessing medium. Water is used throughout all steps

of the dairy industry including cleaning, sanitiza-

tion, heating, cooling and floor washing — andnaturally the requirement of water is huge. Dairy

wastewater is distinguished by the high BOD and

COD contents, high levels of dissolved or suspended solids including fats, oils and grease, nutri-

ents such as ammonia or minerals and phosphatesand therefore require proper attention before dis- posal.

In recent times, researchers have shifted their

interests in possibilities of reuse or recycling of industrial wastewaters — dairy industries are no

exceptions [1,2]. Dairy wastewater generally does

not contain conventional toxic chemicals likethose listed under EPA’s Toxic Release Inventory.

However, it has high concentration of dissolved

organic components like whey proteins, lactose,fat and minerals [3] and it is also malodorous

because of the decomposition of some of the con-taminants causing discomfort to the surrounding population. To comply with the discharge stan-

dard, the dairy industries are practicing an elabo-

rate effluent treatment protocol which is affectingthe overall economy of the plant. The need of the

hour is a suitable technology for recycling or reuse

at least a reasonable quantity of the wastewater produced in the plant.

Recent studies revealed that membrane sepa-

rations may help in solving problem of attaining

a quality of water that can be recycled back to the

process and it was tested for various chemical

industries and in some food processing industries

also [4–7]. Even the dairy industry effluent was

also treated by membrane process and possibility

of reuse was reviewed [1,8]. However the protein-

ous materials of the dairy wastewater were found

to be severe foulant for the existing membrane

materials [9]. With the advent of the newer mem-

brane materials which are less prone to fouling,

the research thrust in this area has increased tre-mendously. To control the fouling and to improve

the productivity and life of membranes, use of

coagulant and adsorbent before membrane ap-

plication were done in primary and secondary

effluent treatment and in sewage effluent treatment

[10–12]. In the present investigation, thorough

pretreatment studies were performed using con-

ventional coagulants and a few newer coagulants

to evaluate their suitability for treatment of dairy

effluent. The effectiveness of use of Na-CMC and

chitosan as coagulant in the treatment of somefood processing industry wastewater such as inegg processing plant and in fish meal factories

had been reported [13,14]. Not much literature is

available on another polysaccharide — alginicacid as coagulant in the treatment of wastewater.

Activated charcoal treatment was done after

coagulation as it is known to remove the color and odor of the surface water and improve the

taste of drinking water combined with some other

treatment options [15,16]. To optimize the con-ditions for chemical pretreatment of dairy waste-

water, studies were undertaken to evaluate theeffects of dosages of coagulants and adsorbents, pH, contact time, settling time etc. before the

membrane processing. Preliminary results of each

chemical pretreatment were evaluated with respectto percent reduction of total dissolved solids (TDS)

and chemical oxygen demand (COD) of treated

water. Membrane separation studies were per-formed in both the dead end system (for labora-

tory-scale studies) and cross flow system (for

pilot-scale studies) and the water quality obtainedafter membrane separations were compared to the

process water actually used by some dairy indus-

tries.

2. Experimental

2.1. Materials

Raw wastewater was collected from A.P. Dairy,

Hyderabad, India at an interval of 15 days and



B. Sarkar et al. / Desalination 195 (2006) 141–152 143

stored in the refrigerator, if required to be usedfor long periods.

2.1.1. Reagents

For the pretreatment studies before membrane

processing different types of coagulants like in-

organic (alum and ferric chloride), polymeric(polyaluminium chloride) and natural organic

(sodium carboxymethyl cellulose commonly

known as Na-CMC, alginic acid, and chitosan)were tested. Alum was purchased from local mar-

ket. Ferric chloride LR grade was procured fromS.D. Fine Chem Ltd., Mumbai whereas poly-aluminium chloride was obtained from Permionics

Pvt. Ltd., Vadodara, Gujarat, India. Alginic acid

(LR grade) was obtained from Loba Chemie Pvt.Ltd., Mumbai, India. Chitosan and Na-CMC were

purchased from Sigma Aldrich Inc., St. Louis,

USA. Powdered activated charcoal (LR grade)was obtained from S.D. Fine Chem Ltd., Mumbai,

India. Commonly used chemicals to maintain the

pH of the medium NaOH and HCl both LR grade

were procured from S.D Fine Chem Ltd, Mumbai

and Ranbaxy Fine Chemicals Ltd, New Delhi,

India respectively.

2.1.2. Membranes

Cellulose acetate flat sheet membranes of 44 cm2 surface area having 10,000 Da and 1,000 Da

molecular weight cut off were supplied by Milli-

pore Corporation, MA, USA. Permionics Pvt.Ltd., Vadodara, India had supplied nanofiltration

membrane of 300 Da molecular weight cut off

(MWCO) and RO flat sheet membrane as complimentary samples. The membranes are poly-

amide on non oven polyester. The ceramic micro-

filtration membrane having 0.45 micron pore sizeused in pilot plant was purchased from Orelis,

France. It is having tubular configuration with 19

channels and 0.167 m2 surface area. Spiral woundRO membrane with 2 m2 surface area was pro-

cured from Osmonics, USA. The membrane is

made up of cellulose acetate and having more than99% NaCl rejection.

2.1.3. Membrane units

The ultrafiltration experiments were performed

in a dead-end test cell supplied by Millipore Cor-

poration, MA, USA. The nanofiltration/reverseosmosis experiments were done in a stainless steel

test cell of dead-end type having maximum pres-

sure limit of 50 bar. This test cell was supplied bySnowtech Pvt. Ltd., Mumbai, India. Both the test

cells were fitted with magnetic stirrer. The trans-

membrane pressure (TMP) was generated bynitrogen gas. Pilot scale cross flow membrane unit

had a feed tank of 50 L capacity and was supplied by Nishotech Systems Pvt. Ltd., Mumbai. Themembranes used in pilot scale studies were housed

in stainless steel casing.

2.2. Analytical methods

Wastewater samples and various water samples

after treatment were analyzed for suspended solid,

total dissolved solid content (TDS), chloride, sul-fate, hardness, oil and grease content (FOG), and

phosphorus content according to the standard

method [17]. pH and conductivity were measuredwith the help of digital pH meter (model: DI 707),

supplied by Digisun Electronics, Secunderabad,India and digital conductivity meter (DCM 900)

supplied by Global Electronics, Hyderabad, India

respectively. Turbidity measurement was donewith Digital Nephelo-Turbiditymeter 132. For

COD estimation the digestion of the sample was

done in a COD reactor, supplied by HACH,Colorado, USA followed by titration with standard

ferrous ammonium sulfate. 5 day 20°C BOD

values were estimated using YSI5100 dissolvedoxygen meter, supplied by YSI Incorporated,

Ohio, USA.

2.3. Experimental procedure

2.3.1. Chemical pretreatment of dairy waste-

water

Wastewater sample collected from dairy farm

was filtered and the filtered water samples were

then subjected to coagulant and PAC treatment.




400 ml of filtered wastewater was taken in 500ml beaker.

a.Optimization of the coagulant dosages:

Coagulant dosages were varied from 100 to

1000 mg/L. Addition of coagulant was followed

by stirring for 5 min on magnetic stirrer and settl-

ing for 120 min. Depending on the analytical re-sults the dosages were further reduced to 10–

100 mg/L in case of chitosan.

b.Optimization of pH for an individual co-agulant : pHs selected were 4.0, 6.5 and 8.0. pH

of the wastewater was maintained with the helpof 1:1 HCl and 0.1N NaOH, whenever required.c. Optimization of settling time after coagula-

tion: The settling time intervals were varied be-

tween 30–150 min to get the best possible results.d. Studies on powdered activated charcoal

treatment: Variable dosages (0.5–2.0 g/L) of PAC

were added to the wastewater sample and stirredon magnetic stirrer for 90 min. The pH of the

wastewater was also varied in the same manner

as mentioned in the coagulant treatment. Thestirring time was varied from 30 to 120 min. The

optimum conditions of PAC treatment wereselected depending on TDS and COD values of the treated water.

2.3.2. Selection of pretreatment sequence

The effects of coagulant treatment followed

by the PAC treatment were evaluated and the

sequence of operation was finalized based on the

percent reduction of TDS and COD.

2.3.3. Membrane processing of pretreated

water

After coagulant and PAC treatment the pH of

the water was adjusted to 6.5, and was passedthrough UF and RO membranes separately in the

test cells and checked for TDS and COD reduc-

tion. For UF treatment the pressure was main-tained at 3–3.5 bar. For RO experiments as high

as 35 bar transmembrane (TMP) pressure was

created to get a reasonably good flux.

In the pilot unit, the wastewater sample after chemical pretreatment and pH adjustment was first

passed through a tubular ceramic microfiltration

membrane having 0.45 micron pore size. Trans-

membrane pressure of 1.75–2 bar was maintained.

The permeate of the MF membrane was then

passed through a spiral wound RO membranewhere the TMP was maintained at 18–20 bar.

3. Results and discussion

The quality of raw dairy wastewater collectedfrom A.P. Dairy, Hyderabad, India varied batch-

wise according to the production of the dairy farm.

Generally it had bad smell and was light greenishin color. Water pH was in the neutral to slight

alkaline range. The high BOD and COD values

indicated that it is heavily contaminated withorganic matter.

The quality of raw dairy wastewater is given

in Table 1.

3.1. Coagulant treatment

Coagulation–flocculation is one of the mostimportant physicochemical treatment steps in in-

dustrial wastewater treatment to reduce the sus-

pended and colloidal materials responsible for turbidity of the wastewater and also for the

reduction of organic matters which contributes to

the BOD and COD content of the wastewater [18,19]. Addition of coagulants involves destabili-

zation of the particulate matters present in the

wastewater, followed by particle collision and flocformation which results in the sedimentation or

Table 1

Characteristics of raw dairy wastewater

pH 5.5–7.5

TSS, mg/L 250–600

Turbidity, NTU 15–30

TDS, mg/L 800–1200

COD, mg/L 1500–3000

BOD, mg/L 350–600




flotation. The performance of a particular coagu-lant depends upon the quality of the wastewater.

Different types of coagulants were selected in the

present study to observe their effects on dairy

effluent. Performance of coagulants was primarily

based on pH, conductivity, TDS and COD values

of treated water.

3.1.1. Effects of inorganic coagulants

Alum was found to be effective coagulant inreducing solids, organics and nutrients in the dairy

industry effluent to reuse it in irrigation [2]. Re-moval of 99% suspended solids with appreciableremoval of COD and turbidity were achieved

when slaughterhouse wastewater was treated with

alum in the range of 100–1000 mg/L and pH inthe range of 4–9 [19]. Ferric chloride had shown

better results than alum in the removal of COD

and suspended solid and in the reduction of color in a cost effective way for the clarification of tan-

nery wastewater. The performance of the coagu-

lants was highly dependent on pH and dosages

[20].

The most commonly used inorganic coagulants

in wastewater treatment; alum and ferric chloride

were therefore tried in initial experiments. As the

dosages of the coagulants were increasing, the

formation of floc followed by settling was appre-

ciable in both the cases at pH 6.5 and 8.0. No co-

agulation was observed at pH 4.0 for ferric

chloride which is reflected in Fig. 1a. At 500 mg/L

dosage of ferric chloride the TDS is showing mini-

Fig 1a. Variation of TDS with ferric chloride dosage. Fig. 1b. Variation of TDS with alum dosage.

mum when the starting pH is in the range of 6.5– 8.0. Alum also showed the same trend and at

500 mg/L dosage and at pH 6.5–8, TDS was found

to be minimum (Fig. 1b). Hydrolysis of Al2(SO

4)

3

and FeCl3in the alkaline medium at that particular

dosage results in the formation of corresponding

gel like hydroxides and some positively chargedmononuclear and polynuclear species. These posi-

tively charged compounds combine with nega-

tively charged colloidal particles present in thewastewater by charge neutralization mechanism

and at the time of settling under gravity these hyd-roxides and complexed hydroxides sweep awayremaining uncharged/ charged colloidal particles

of the wastewater with them and precipitates out

[21]. The increase of TDS after that particular dosage may attribute to the optimum hydrolysis

of the coagulants at that particular dosage. The

hydrolysis of these coagulants results in the forma-tion of strong acids which enhances the ionic

strength of the medium.

As a result, pH of the medium was found todecrease and conductivity was found to increase

with coagulant dosages as shown in Figs. 2a and2b. Use of ferric chloride at higher dosages pro-duces orange colored water. These results prompt-

ed us to search for other coagulants.

3.1.2. Effect of polymeric coagulant

Coagulation using inorganic coagulants may

result in the production of huge volume of sludge

and aluminium or iron salts may be retained in




Fig. 2a. Effect of coagulant dosages on the pH of the

medium.

the treated water. It is well known that uptake of

aluminium is associated with Alzheimer’s diseases

[22] and blood cancer. Synthetic polymeric co-

agulants were known to have some advantages

over these inorganic coagulants. Polyaluminium

chloride (PACl) is one of the most commonly used polymeric coagulants used in wastewater treat-

ment. Treatment of secondary effluent from con-

ventional wastewater treatment plant with poly-

aluminium chloride at pH 6.0 resulted in removalof 95% turbidity as compared to alum and ferric

chloride [23]. In our study we observed that, incontrast to alum, poly aluminium chloride kept

the pH of the medium very stable with increase

in dosages and it did not have any significant effecton the reduction of solid content in case of dairy

wastewater.

3.1.3. Study on natural organic coagulants

Polymeric coagulants involve in the produc-

tion of lower volume of sludge and its effective-ness is not very much dependent on the pH of the

water. However, use of these coagulants are re-

stricted because of the production of chlorinated

and several other by-products in water which have

adverse impact on human health [24]. Natural

organic materials are biodegradable and mostly

non toxic in nature and less polluting to environ-

ment. Na-CMC and alginic acid — two members

Fig. 2b. Effect of coagulant dosages on the conductivity

of the medium.

in that category had been reported as coagulant

in treatment of dairy wastewater [25,26]. In this

study, therefore, these two coagulants were also

tried for their effectiveness. However no floc

formation was found in the entire pH range. After

analysis it was observed that although the pH of

the treated water did not change much with

dosages as happened with inorganic coagulants,

the TDS was found to increase with dosages as

shown in Figs. 3a and 3b. Being high molecular weight compounds, Na-CMC and alginic acid

instead of performing as coagulant may lead to

increase the TDS with dosages. The higher rate

of increase of TDS after alginic acid treatmentconfirms the higher average molecular weight of

alginic acid compared to Na-CMC. It was there-

fore decided not to use these coagulants for further studies.

Chitosan is another high molecular weight

organic compound obtained from natural sourcelike shells of shrimp, crab, and lobster and also

biodegradable and non toxic in nature and it hasvery high affinity to proteins [25,27]. 100– 700 mg/L dosages of chitosan had been used in

the treatment of pulp and paper mill wastewater

and 2–15 g/L was applied in distillery wastewater treatment [28,29]. Only 26–28% reduction in total

solid was observed in fisheries wastewater when

treated with chitosan at an optimal 60 mg/L dosageat pH 5.5 [30].




Fig. 3a. Effect of Na-CMC dosages on TDS at different

pHs.

Fig.3b. Effect of alginic acid dosages on TDS at differ-

ent pHs.

Therefore it was decided to check its suitability

for the pretreatment of dairy wastewater and it

was observed that the conductivity and pH of the

medium were appreciably constant with dosages

of chitosan.

The dairy wastewater when treated with

chitosan at a dosage of 100 mg/L had resulted in

TDS values of the wastewater 440–540 mg/L in

the pH range of 4.0–6.5 as shown in Fig. 4a. In

Fig. 4b the change of COD of the wastewater with

dosages of chitosan is observed and at 100 mg/Lof chitosan dosage the COD is in the range of

450–680 mg/L when the pH is in the range of 4.0– 6.5.

Since chitosan is a costly coagulant compared

to other coagulants it was decided to check theeffect of lesser dosages. Dosages were again

varied between 10–100mg/L at pH 6.5 and 4.

A maximum of 22% reduction in TDS and 20%decrease in COD was observed at pH 6.5 when

Fig. 4a. Effect of chitosan dosages on TDS at different

pHs.

Fig. 4b. Effect of chitosan dosages on COD at different

pHs.

treated with chitosan in the dosage range below

100 mg/L. At pH 4.0 these reductions were 48%

in TDS and 57% in COD at 10–50 mg/L chitosan

dosage. To make the treatment protocol cost effec-

tive for industry 10 mg/L dosage was selected at

pH 4.0. Chitosan contains two highly polar –OH

and –NH2

groups and have pK avalue nearly 6.5.

In the acidic medium, i.e. at pH less than 6.5 it is

cationic in nature and forms –NH3

+ group and at-

tracts the negatively charged protein molecules

present in dairy wastewater and reduces the solidcontent appreciably [27].

Once the coagulant and its dosages were select-ed the settling time for coagulation was varied

between 30–150 min at a particular coagulant do-

sage and at a particular pH. After 60 min settlingtime no more further reduction in TDS and COD

was observed with time. Fig. 5 shows approx. 44%

TDS and 40% COD reduction after 60 min settlingtime when treated with 10 mg/L chitosan at pH 4.




Chitosan was found to have significant effectas coagulant for the dairy wastewater taken for

treatment in the present investigation. It had

lowered the TDS and COD values considerablyat very low dosage as compared to the common

coagulants. Since the required dosage was very

less, it might be used commercially as a coagulantin the pretreatment of dairy wastewater. The con-

ductivity did not increase after chitosan treatment

which may help in designing the final reverse os-

mosis step. However odor was still persistent after

treatment with chitosan.

3.2. PAC treatment on raw wastewater

Powdered activated charcoal (PAC) had been

used as adsorbent in various industrial wastewater treatments. Olive mill effluent with high COD,

BOD and phenolic content when treated with PAC

had shown 94% removal of phenols with 83% re-moval of other organic matter at an optimum con-

centration of PAC [31]. Removal of phthalate fromwastewater was done by modified activatedcarbon, performance of which was pH dependent

[32]. Treatment of dairy wastewater with some

low cost adsorbents and PAC had shown that PACwas better in lowering TDS than other pretreated

adsorbents like bagasse, straw dust, saw dust,

coconut coir and fly ash [33]. In our present work,an adsorption study with PAC was done on filtered

Fig. 5. Percent reduction of TDS and COD with coagula-

tion settling time after 10 mg/L chitosan dosage at pH = 4.

raw wastewater to optimize pH, dosage, and con-tact time of PAC.

Fig. 6 shows the effect of pH of the wastewater

on the adsorption properties of PAC. A Maximum

of 40% and 62% reduction of TDS and COD

respectively were observed at pH 4. This may be

due to the generation of positive charge on thesurface of charcoal particles in the acidic pH which

attract negatively charged organic molecules

abundantly present in the wastewater and remove by charge neutralization.

Varied dosages of PAC were added to thewastewater having 730 mg/L and 1532 mg/L TDSand COD respectively at pH 4. Stirring time was

fixed at 90 minutes. Optimum dosage of PAC was

found to be 1.5 g/L as shown in Fig. 7 and the re-duction of TDS and COD were 44% and 60%

Fig. 6. % removal of COD and TDS after 1.5 g/L char-

coal treatment at different pHs.

Fig. 7. Variation of TDS and COD with PAC dosages at

pH 4.0.




respectively. With further increase of PAC dosagethere was no appreciable reduction of TDS and

COD.

The variation of TDS and COD with time using

1.5 g/L PAC at pH 4 is shown in Fig. 8. With in-

creasing time the TDS and COD values were de-

creasing and at 90 min of time maximum removalof 44% and 68% of TDS and COD respectively

were observed.

From the above experiments it may be con-cluded that after treatment of filtered raw dairy

wastewater with 1.5g/L PAC at pH 4 and 90 minstirring time, the reduction of TDS was 40–44%and COD was 60–68%. The color and odor had

been eliminated also. This optimized PAC treat-

ment protocol was tried after coagulant treatedwastewater.

3.3. Optimization of pretreatment protocol

After 10 mg/L chitosan treatment at pH 4.0

the filtered water was treated with already opti-

mized 1.5 g/L dosage of PAC at the same pH and

stirred on magnetic stirrer for 90 min and then

again filtered. Results show 57% reduction in TDS

along with 62% reduction in COD as shown in

Fig. 9. No change in conductivity was observed.

Color and odor were removed completely. The

quality of the treated water was found to be

reasonably good for further processing through

membranes.

Fig. 8. Variation of TDS and COD with stirring time af-

ter 1.5 g/L PAC treatment at pH 4.

3.4. Membrane processing in test cells

The chemically pretreated wastewater was

passed through 10,000 Da followed by 1,000 Da,

and reverse osmosis membranes separately in adead end test cell. Appreciable reduction in TDS

and COD was not seen after UF. After passing

through RO membrane a complete water analysiswas done on the permeate and results obtained

are given in Table 2.

3.5. Pilot-scale membrane separation studies

To reduce the fouling of spiral-wound RO

membrane, a MF pretreatment was given before

reverse osmosis to arrest the charcoal particles,fat molecules having bigger sizes and the micro-

organisms present in the wastewater. 71% FOG

along with 81% BOD reduction was observedafter MF run. Raw water turbidity reduction was

observed 88% only after pH adjustment to 4.0.

This may be due to the coagulation and agglo-meration followed by precipitation of milk protein

particularly casein molecules in acidic pH. Coagu-

lant treatment further removed suspended andcolloidal materials lowering further turbidity. PAC

treatment after coagulant treatment significantlychanged the appearance of the wastewater — it

became clear and odorless. COD in RO feed after

MF came down to 197 mg/L. Reverse osmosistreatment reduced 98% COD from original. BOD

Fig. 9. Treatment of dairy wastewater with 10mg/L

chitosan followed by 1.5g/L charcoal at pH 4.

0

500

1000

1500

2000

2500

0 50 100 150

Stirring time (min)

T D S a n d C O D

( m g / L )

TDS(mg/L)

COD(mg/L)




and COD values of the wastewater came down to

8 mg/L and 16.5 mg/L respectively after reverse

osmosis treatment. Drastic reduction in waste-

water conductivity after RO (96% from the pre-

vious step) signifies the rejection of ionic species

only by reverse osmosis and the results are tabu-

lated in Table 3.

Table 2

Analysis of dairy wastewater after pretreatment and membrane processing in test cell unit

Raw filtered dairy

wastewater

Wastewater

at pH 4

After 10 mg/L

chitosan treatment

After 1.5 g/L PAC

treatment

After RO

processing

pH 5.84–6.71 — 4.09–4.25 4.38–4.71 6.15–6.43

Conductivity, µS/cm 556–880 616 –920 638–797 646– 803 47–111

Turbidity, NTU 15–30 8.4 3.6–3.8 0.3–0.1 0–0.06

TDS, mg/L 696–980 350–950 260–440 100–200 57–90

Hardness, mg/L 150–200 150–200 150–200 150–200 19–28

Chloride, mg/L 58–71 209–264 209 204–209 58–60

Sulphate, mg/L 25–131 84 62–81 50–82 17–30

Phosphorus, mg/L 0–1.64 0–1.68 0–1.64 nil nilCOD, mg/L 405–1308 405–1165 203–583 203–388 81–117

Fat oil and grease, mg/L 86–252 182 83 60 nil

Color White White Turbid Clear Clear

Odor Bad smell Bad smell Reduced Absent Absent

Table 3

Analytical results of dairy wastewater after pretreatment and membrane processing in pilot plant unit

Filtered raw

dairy wastewater

Wastewater

at pH 4

After 10mg/L

chitosan treatment

After 1.5g/L

PAC treatment

MF permeate RO permeate

pH 6.61 4.06 4.21 5.16 6.53 6.55Conductivity, µS/cm 923 920 933 987 1057 40

Turbidity, NTU 16 2.1 1.9 0.3 0.1 0

TDS, mg/L 780 920 470 360 300 33

TSS, mg/L 216 nil nil nil nil nil

Hardness, mg/L 125 125 125 125 125 3

Chloride, mg/L 70.4 309 307 289 260 16

Phosphorous, mg/L 1.5 1.5 1.5 nil nil nil

COD, mg/L 1080.5 884 295 197 197 16.5

FOG, mg/L 216 156 56 50 14 nil

BOD, mg/L 540 540 520 440 85 8

Color White White Turbid Clear Clear Clear

Odor Bad smell Bad smell Reduced Absent No smell No smell

3.6. Comparison of dairy process water with ROwater

The process water sample used in some localdairy industries was collected. These samples wereanalyzed and compared with the permeate of re-verse osmosis studies done earlier. The results areshown in Table 4.




4. Conclusion

Chitosan at very low dosage, 10 mg/L was found

to be a better coagulant compared to inorganic

and organic coagulants. PAC treatment after chito-

san was found to be useful in complete removal

of color and odor of the wastewater before mem-

brane processing. Performance of chitosan and

PAC is pH dependent. Chitosan and PAC work

efficiently at the same pH 4.0 and comprise the

RO pretreatment step suitable for dairy waste-

water. Pilot scale experiment using spiral woundRO membrane yields better water quality com-

pared to flat sheet membranes used in bench scale

experiments. The quality of water after reverseosmosis was found to be comparable to that of

process water used in the Dairy and can be re-

cycled back.

Acknowledgement

B.S. and A.V. acknowledge the Council of Sci-entific and Industrial Research (CSIR), India for

awarding senior research fellowship and junior

research fellowship respectively. The authors arethankful to A.P. Dairy, Hyderabad, India for their

cooperation in supplying wastewater during the

course of this study. The authors wish to thank Permionics, Vadodara, India for giving polyalumi-

nium chloride and RO flat sheet membrane used

in the experiment as a complimentary sample.

Table 4

Comparison of RO water with dairy process water

Process water RO permeate

pH 7.3 6.5

Conductivity, µS/cm 242 40

Turbidity, NTU 0.2 0.0

TDS, mg/L 128 33Hardness, mg/L 88 3

FOG, mg/L Nil Nil

Chloride, mg/L 58 16COD, mg/L 24.7 16.5

References

[1] B. Balannec, G. Gesan-Guiziou, B. Chaufer, M.

Rabiller-Baudry and G. Daufin, Treatment of dairy

process waters by membrane operations for water

reuse and milk constituents concentration, Desalina-

tion, 147 (2002) 89–94.

[2] M.F. Hamoda and S.M. Al-Awadi, Improvement of

effluent quality for reuse in a dairy farm, Water Sci.

Tech., 33(10–11) (1996) 79–85.

[3] R. Mukhopadhyay, D. Talukdar, B.P. Chatterjee and

A.K Guha, Whey processing with chitosan and isola-

tion of lactose, Process Biochem., 39 (2003) 381–

385.[4] K.H. Ahn, J.H. Song and H.Y. Cha, Application of

tubular ceramic membranes for reuse of wastewater

from buildings, Water Sci. Tech., 38(4–5) (1998)

373–382.

[5] V. Mavrov and E. Belieres, Reduction of water con-

sumption and wastewater quantities in the food in-

dustry by water recycling using membrane pro-

cesses, Desalination,131 (2000) 75–86.

[6] M. Marcucci, G. Nosenzo, G. Capannelli, I. Ciabatti,

D. Corrieri and G. Ciardelli, Treatment and reuse of

textile effluents based on new ultrafiltration and

other membrane technologies, Desalination, 138

(2001) 75–82.[7] M.D. Afonso and R. Borquez, Nanofiltration of

wastewaters from the fish meal industry, Desalina-

tion, 151 (2002) 131–138.

[8] I. Koyuncu, M. Turan, D. Topacik and A. Ates,

Application of low pressure nanofiltration mem-

branes for the recovery and reuse of dairy industry

effluents, Water Sci. Tech., 41(1) (2000) 213–221.

[9] S.S. Madaeni and Y. Mansourpanah, Chemical

cleaning of reverse osmosis membranes fouled by

whey, Desalination, 161 (2004) 13–24.

[10] D. Abdessemed and G. Nezzal, Treatment of primary

effluent by coagulation–adsorption–ultrafiltration

for reuse, Desalination, 152 (2002) 367–373.[11] S.L. Kim, J. Paul Chen and Y.P. Ting, Study on feed

pretreatment for membrane filtration of secondary

effluent, Sep. Purif. Tech., 29 (2002) 171–179.

[12] W.S. Guo, S. Vigneswaran, H.H. Ngo and H. Chap-

man, Experimental investigation of adsorption–

flocculation–microfiltration hybrid system in waste-

water reuse, J. Membr. Sci., 242 (2004) 27–35.

[13] L.J. Xu, B.W. Sheldon, R.E. Carawan, D.K. Larick

and A.C. Chao, Recovery and characterization of

by-products from egg processing plant wastewater




using coagulants, Poultry Sci., 80 (2001) 57–65.

[14] L. Guerrero, F. Omil, R. Mendez and J.M. Lema,

Protein recovery during the overall treatment of

wastewaters from fish-meal factories, Bioresource

Technol., 63 (1998) 221–229.

[15] B. Ericsson and G. Trägårdh, Treatment of surface

water rich in humus — Membrane filtration vs. con-

ventional treatment, Desalination, 108 (1996) 117–

128.

[16] E.E. Hargesheimer and S.B Watson, Drinking water

treatment options for taste and odor control, Wat.

Res., 30(6) (1996) 1423–1430.

[17] APHA, Standard Methods for the Examination of

Water and Wastewater, 20th ed., 1998.[18] M. Rossini, J.G. Garrido and M. Galluzzo, Optimi-

zation of the coagulation–flocculation treatment:

influence of rapid mix parameters, Wat. Res., 33(8)

(1999) 1817–1826.

[19] N.Z. Al-Mutairi, M.F. Hamoda and I. Al-Ghusain,

Coagulant selection and sludge conditioning in a

slaughterhouse wastewater treatment plant, Biore-

source Technol., 95 (2004) 115–119.

[20] Z. Song, C.J. Williams and R.G.J. Edyvean, Treat-

ment of tannery wastewater by chemical coagula-

tion, Desalination, 164 (2004) 249–259.

[21] National Water Quality Management Strategy,

Australian Drinking Water Guidelines, DrinkingWater Treatment Chemicals, Draft for Public Con-

sultation, February 2005.

[22] C. Huang, S. Chen and J. Ruhsing Pan, Optimal con-

dition for modification of chitosan: a biopolymer

for coagulation of colloidal particles, Wat. Res.,

34(3) (2000) 1057–1062.

[23] S. Delgado, F. Diaz, D. Garcia and N. Otero, Behavi-

our of inorganic coagulants in secondary effluents

from a conventional wastewater treatment plant,

Filtr. Sep., Sept (2003) 43–46.

[24] J.F. Lee, P.M. Liao, D.H. Tseng and P.T. Wen, Be-

haviour of organic polymers in drinking water purifi-

cation, Chemosphere, 37(6) (1998) 1045–1061.

[25] E.S. Olsen, H.C. Ratnaweera and R. Pehrson, A

novel treatment process for dairy wastewater with

chitosan produced from shrimp-shell waste, Wat.

Sci. Tech., 34(11) (1996) 33–40.

[26] S. Taha, D. Tremaudan and G. Dorange, Comparative

study of coagulation–decantation and UF for elimi-

nation of organic carbon from dairy wastewater,

Recent Prog. Genie Proced., 9 (1995) 55–60.

[27] B. Krajewska, Membrane-based processes perform-

ed with use of chitin/chitosan materials, Sep. Purif.

Technol., 41(3) (2005) 305–312.[28] H. Ganjidoust, K. Tatsumi, T. Yamagishi and R.N.

Gholian, Effect of synthetic and natural coagulant

on lignin removal from pulp and paper wastewater,

Wat. Sci. Tech., 35(2–3) (1997) 291–296.

[29] I.G. Lalov, I.I. Guerginov, M.A. Krysteva and K.

Fartsov, Treatment of waste water from distilleries

with chitosan, Wat. Res., 34(5) (2000) 1503–1506.

[30] C.V. Genovese and J.F. Gonzalez, Solids removal

by coagulation from fisheries waste waters, Water

SA, 24(4) (1998) 371–372.

[31] M.O. Azzam, K.I. Al-Malah and N.I. Abu-Lail, Dy-

namic post-treatment response of olive mill effluent

wastewater using activated carbon, J. Environ. Sci.Health Part A, 39(1) (2004) 269–280.

[32] N. Adhoum and L. Monser, Removal of phthalate

on modified activated carbon: application to the

treatment of industrial wastewater, Sep. Purif.

Technol., 38 (2004) 233–239.

[33] M. Rao and A.G. Bhole, Removal of organic matter

from dairy industry wastewater using low-cost ad-

sorbents, J. Indian Chem. Eng. Section A, 44(1)

(2002) 25–28.

Documents

Possibility of Reuse of Waste Water in Dairys