Recycling of wastewaters of textile dyeing industriesusing advanced treatment technology and

cost analysis—Case studies

K. Ranganathan ∗, K. Karunagaran, D.C. SharmaCentral Pollution Control Board, Southern Zonal Office, Rajajinagar, Bangalore 560 086, India

Received 30 January 2006; received in revised form 22 June 2006; accepted 22 June 2006Available online 26 July 2006

Abstract

Textile dyeing industries in Tirupur and Karur of Tamil Nadu (India) usually discharge effluentsranging between 80 and 200 m3/t of production. Dyeing is performed either by conventional winchprocess or by advanced soft flow reactor process. Hypochlorite, the commonly used bleaching chem-ical is being gradually phased out by alkaline hydrogen peroxide solution that generates less effluentand fewer solids in the effluents. Coloring of yarn/cloth takes place in the presence of high concentra-tion of sodium chloride or sodium sulphate (25–75 kg/m3) in dye solutions. Dye bath wastewaters andwash waters are the process effluents of dyeing industry which are collected separately or togetherand follow the advanced treatment for maximum recycling of recovered waters.

Dye bath water after treating by sand and nanofiltrations (NF), the permeate is used in process fordye bath preparation and the reject of about 20–30% is sent to multi effect evaporator (MEE)/solarevaporation pond (SEP). Wash waters treated using a sequence of physicochemical and biological unitprocesses are passed into two stages reverse osmosis (RO) membrane systems and then the permeate isreused in the processes. The rejects about 15–20% of the inlet volume is subject either to nanofiltrationfor salt recovery or sent to evaporators. The final rejects from nanofilter systems is directed to multieffect evaporator system where condensed waters are recovered. The removal of total dissolved solids(TDS), chemical oxygen demand (COD), chloride and sodium are in the range of 80–97%, 91–97%,

Abbreviations: INR, Indian rupees (one USD equal to INR 44); CPCB, Central Pollution Control Board;APHA, American Public Health Association; RO, reverse osmosis; NF, nanofiltration; MEE, multiple effectevaporators; TDS, total dissolved solids; BOD, biochemical oxygen demand; COD, chemical oxygen demand;SAR, sodium absorption ratio; TH, total hardness

∗ Corresponding author. Tel.: +91 80 23495981; fax: +91 80 23498207.E-mail address: rangacpcb@yahoo.com (K. Ranganathan).

0921-3449/$ – see front matter © 2006 Elsevier B.V. All rights reserved.doi:10.1016/j.resconrec.2006.06.004

76–97% and 96%, respectively. Multiple effect evaporators out flows of about 2–3% of the effluentvolume are allowed for solar evaporation and the solids are disposed off. The cost of operation ofMEE is about INR 400/m3 of the rejects. The cost of water recovery is about INR 60–80/m3 includingcommissioning and maintenance whereas price of raw-water in Tirupur is about INR 100/m3.© 2006 Elsevier B.V. All rights reserved.

Keywords: Dyeing industry; Wastewater recycling; Reverse osmosis; Membrane process; Nanofiltration

1. Introduction

Next to food the second basic needs of man ‘cloth’ is supplied by processing of naturaland synthetic fibers in the industries called textiles. Increased population and modernizedcivilization trend gave rise to blooming of textile sectors in India. An estimate shows thattextiles account for 14% of India’s industrial production and around 27% of its exportearnings. India is the second largest producer of cotton yarn and silk and third largestproducer of cotton and cellulose fiber (Report of Business India, 2004). The total productionof yarn during the year 2003–2004 was 3051 kt (Annual Report of Ministry of Textiles,2004). There are about 10,000 garment manufacturers and 2100 bleaching and dyeingindustries in India. Majority are concentrated at Tirupur and Karur in Tamil Nadu, Ludiyanain Punjab and Surat in Gujarat. The processes followed in textile industries are spinning offiber to yarn, sizing to improve stiffness, scouring, kiering and desizing to remove excesssizing materials, bleaching to remove pectin and wax from the yarn and fabric and coloringand printing to provide desired color and design to the cloth. Dyeing is a combined process ofbleaching and coloring, which generates voluminous quantities of wastewaters and in turncauses environmental degradation. The effluents consist of high TDS, sodium, chloride,sulphate, hardness and carcinogenic dye ingredients. High BOD effluents are generatedfrom the sizing and desizing processes and treated by conventional anaerobic and aerobicbiological methods (Tchobanoglous and Burton, 1995).

Coimbatore district of Tamil Nadu is well known for cotton production and also called asManchester of Southern India. Tirupur, one of the towns in Coimbatore District is located atthe bank of river Noyyal, a tributary to river Cauvery. The quality of Noyyal river water andclimatic condition of Tirupur has been ideal for dyeing operation of yarn and fabric sincelong time. Presently there are 712 dyeing and bleaching industries in Tirupur that generate87,000 m3/d of wastewater. Out of this a total of 281 industries are attached with commoneffluent treatment plants (CETP) and others are having their individual effluent treatmentplants. Presently adopted technology is able to remove the color and other organic impuritiesto the stipulated standards but failed to arrest the inorganic contaminants. Continuanceof effluent discharges has caused gross damages to the nearby aquatic systems receivingbody like Orathupalayam dam located at the down stream of river Noyyal and as suchthe water quality has become unfit for irrigation. The reservoir water’s TDS, chloride andsodium were reported as high as 5054, 2869 and 1620 mg/L, respectively (Central PollutionControl Board, 2005). Also the concentration of dissolved solids in the ground and riverwater is reported in the range of 5000–7000 mg/L i.e. almost ten times higher than thedesirable drinking water standard (Indian Standard, 1991). A study carried out by Rajaguru

et al. (2002) indicates that the ground water in the Tirupur area is also contaminated withsubstances capable of inducing DNA damage in human cells. One more town Karur locatedat the bank of river Amaravathy, another tributary to river Cauvery is also concentrated with600 bleaching and dyeing industries. Advanced treatment technologies are imperative toprotect the water resources in these areas.

Membrane technology for treatment of dye house effluents was studied by Bucklay(1992) and reported 95% color removal. Vandevivere et al. (1998) and Ciardelli et al.(2000) have reviewed and studied successful application of membrane technology in textilewet processing industries. In view of the above impacts of the dyeing effluents on theenvironment, the industries in Tirupur and Karur are also forced to adopt technology leadingtowards zero discharge systems. There are 20 dyeing industries that have already installedeffluent treatment technologies with advanced techniques and attained zero discharge. Fourindustries adopted such technologies are extensively studied and the results are discussedin this paper.

2. Materials and methods

Four dyeing units namely M/s. Sivasakthi Textile Processors, Tirupur, M/s. RennaisanceCreations Processing Division, Tirupur, M/s. Leeds Spinning Mills (P) Ltd., Tirupur andM/s. Karur Amaravathy Textiles Industry, Karur were visited and information on manu-facturing process, production status and wastewater quantity were collected. Waste watersamples from the dye bath collection tank and wash water collection tanks, intermediatepoints and at the outlets of effluent treatment plants were collected and analyzed at mobileas well as stationary laboratory using standard methods. Eight hourly composite and grabsamples were collected for the first two units and other two units, respectively. The sampleswere preserved and analyzed as per the standard methods (APHA, 1995; CPCB, 2001).

Percent sodium and sodium absorption ratio (SAR) values were calculated using thefollowing formulas:

percent sodium = concentration of Na × 100

concentrations of Na + K + Ca + Mg

sodium absorption ratio (SAR) = concentration of Na√(concentration of Ca + concentration of Mg)/2

where the concentrations of the ions are expressed in mequiv./L. All the chemicals usedwere of analytical and laboratory grades.

3. Results and discussion

3.1. M/s. Sivasakthi textile processors

M/s. Sivasakthi Textile Processors engaged in dyeing of yarn (cotton and polyester)is located at Mangalam, Tirupur. Six numbers of soft flow reactors (batch process) with

different capacities are used for dyeing including wetting, bleaching, neutralizing, washing,coloring, washing, etc. In the reactors, 1 t of cotton yarn requires 10 m3 of water whereas 1 tof polyester yarn consumes only 4 m3 in each steps. Dye bath solution requires dyes, alkaliand sodium salt in the process. Quantity of salt (sodium chloride) used usually dependson the requirement of color shade. The total quantity of yarn/fabric processed in the unitis 1500–2000 kg/d and the volume of effluent generated is of the order of 100–200 m3/d.Effluents are segregated into dye bath wastewater and wash water and treatment is effectedaccordingly.

Wash water is collected in holding tanks and pumped to primary treatment unit (lime andferrous sulfate slurries are flash-mixed with effluent and allowed for settling). Followingprimary treatment the effluent is carried to pressure sand filter, iron removal filter, ionexchange filter and reverse osmosis (RO) system. Double stage RO system (each with sixmembranes) with spiral wound membrane is in operation. Pump pressure is maintained inthe range of 21.2–28.2 kg/cm2. Rejects of first RO is sent to second RO and the final reject(20%) is sent to MEE. Condensate water is recycled in the cleaning operations. Outlet with100 g/L solid content is allowed for solar evaporation and the combined permeate is used inthe process. Dye bath water is collected in a separate tank and are subject to nanofiltrationafter following pre-filtration. Total reject of about 30% is sent for multi effect evaporationand solar evaporation systems. The permeate is used for preparation of dye bath solution.The characteristics of the raw effluents, intermediate effluents and permeate are presentedin the Table 1. The low hardness of permeate is an added advantage in the process. Permeateof NF filtration contains 4.8% of salts that is mixed with more salts and used in the process.Salt recovery from the dye bath alone has 50% returns.

3.2. M/s. Renaissance creations processing division

M/s Renaissance Creations is located at Kuppandampalayam, Tirupur. Dyeing of clothand garment of cotton is practiced in the unit. The both Winch and soft flow reactors(batch process) are used for dyeing. The process includes wetting, bleaching, neutralizing,washing, coloring, washing, etc. Dye bath solution requires dyes, alkali and sodium salt(sulphate and chloride) in the process. Quantity of the product is 3000 kg/d and the volumeof effluent generated is 600 m3/d. Effluent is segregated into dye bath wastewater and washwater, which is generally in the ratio of 1:10.

Wash water equalized in a holding tank is subject to primary treatment by flash mixingwith lime and ferrous sulfate and are allowed for settling. Primary treatment is followed bythe secondary treatments such as biological oxidation through Tricking filters, chlorination,activated carbon bed and pressure sand filter before entering into reverse osmosis (RO)system. Double stage RO is followed with a feed water flow rate of 27.5 m3/h. High pressurepumps used to feed the filtered water to the first array of the RO and the reject of first ROto second RO and the final reject (12–15%) is sent for multi effect evaporator. Permeate isused in the process after passing through degasser tower.

Whereas dye bath water is collected in a separate tank and allowed for lime and ferroussulfate flocculation to remove the color. These light color effluents mixed with the rejectsof RO are sent to evaporation system (MEE). Condensed water is recycled in the processand the rejects are diverted to crystallizing system for recovery of Glaubers salt which

Table 1Characteristics of effluents of M/s. Shivasakthi Textile Processors, Tirupur

Parameter Wash water Dye bath water

Inlet to ETP Outlet of chemicaltreatment

RO permeate RO reject Dye bathwastewater

NF reject

pH 9.76 9.78 7.52 8.21 10.42 8.21Electrical conductivity (mS/cm) 6.80 6.63 0.77 32.1 53.9 63.55Total suspended solids (mg/L) 47 26 BDL 46 76 60Total dissolved solids (mg/L) 4280 3620 474 21670 39179 48294BOD (mg/L) 80 63 10 450 180 100COD (mg/L) 317 204 24 1143 909 402Total hardness (mg/L) as CaCO3 320 141 3 728 88 45Ca-hardness (mg/L) as CaCO3 272 104 3 687 68 22Sulphate (mg/L) 75 116 8 328 174 362Chloride (mg/L) 1912 1771 184 10756 19179 26432Sodium (mg/L) 1600 – – 9280 – 20480Potassium (mg/L) 38 – – 208 – 62Percent sodium 90 – – 95 – 100Sodium absorption ratio (SAR) 39 – – 146 – 1329

Note: BDL, below detection limit; –, not analysed.

is used in the process. The characteristics of effluents are presented in the Table 2. Thequality of permeate shows that is suitable for dye house processing. The high TDS andchloride contents in the permeate indicates that the RO membrane has to be either cleanedor replaced.

3.3. M/s. Leeds spinning mills Ltd

The industry which process 4000 kg of yarn and fabric per day generates 3000 m3/d ofwash water and 30 m3/d of dye bath water. The wash effluents and bath effluent are collectedseparately and treatment is effected. The dye bath effluents are subject to nanofiltration aftergravitational settling. NF modules are extremely sensitive to fouling by colloidal materialsand polymers. It can be used to separate fiber reactive dyes and cationic dyes from thesalt. The permeate collected contains merely NaCl that is used in the dyeing process. Therejects are diverted to solar evaporation ponds. The wash waters after treating with limeand ferric chloride is passed to sand filtration followed by iron removing cartridges. It isthen subjected to double stage reverse osmosis system and 80% of permeate is used inthe industrial process and the reject are sent for nanofiltration and solar evaporation. Solarevaporation pond is designed keeping water evaporation rate of 4 mm/d. To minimize thearea requirement for solar evaporation, the industry has proposed to install one more ROsystem in conjunction with treatment plant. The results of treated and untreated waters arepresented in the Table 3. The permeate has shown the lowest TDS concentration of 212 mg/Lout of the studied industries.

Due to scarcity of fresh water in the area, the unit had purchased 400 m3/d of waterthrough tankers. After installation of the advanced water recovery system, the unit is pur-chasing only 3–4 m3/d.

3.4. M/s. Karur Amaravathi textiles industry

The unit located at the bank of river Amaravathy processes yarn and fabric dyeing withproduction capacity of 4000 kg/d and generates effluent of about 400 m3/d. Both wash watersand dye bath waters are collected together in a tank and subject to advanced treatment. Thereis no system for BOD, color and other impurities removal. The effluent is sent directly to thedisc type RO membrane after settling. There are four modules in the RO system wherein therejects of first module is sent to second module and so on. Permeates from the each moduleare collected together and recycled back in the industrial processes. The rejects of the lastmodule are subject to nanofiltration and permeate is used for making dye solution and thereject is sent for solar evaporation. The characteristics of effluent, inlet to RO, individualpermeate, combined permeate and rejects are shown in the Table 4. The BOD of permeateis high due to no prerequisite of primary and secondary treatment of wastewaters.

3.5. Comparison of the ROs performance in the studied textile dyeing units

The characteristics such as TDS, chloride, percent sodium and SAR show that theuntreated and primarily treated wastewaters are unfit for irrigation and their discharge intoriver may further aggravate the problem. Therefore, the advanced treatments such as reverse

Table 2Characteristics of effluents of M/s. Renaissance Creations, Tirupur

Parameter Wash water Dye bath wastewater

Inlet to ETP Outlet of chemicaltreatment

Inlet to RO ROpermeate

RO reject

pH 9.28 7.36 7.68 7.88 7.77 9.78Electrical conductivity (mS/cm) 8.99 8.64 8.47 1.97 19.85 17.35Total suspended solids (mg/L) 90 24 8 BDL 23 57Total dissolved solids (mg/L) 5072 4862 4764 1032 12138 10522BOD (mg/L) 107 47 24 2 13 45COD (mg/L) 288 154 108 27 135 240Total hardness (mg/L) as CaCO3 121 101 141 9 182 606Ca-hardness (mg/L) as CaCO3 66 24 61 5 131 343Sulphate (mg/L) 309 451 470 43 1748 171Chloride (mg/L) 2161 2336 2325 528 5373 4766Sodium (mg/L) 1880 – – – 3760 –Potassium (mg/L) 40 – – – 74 –Percent sodium 96 – – – 97 –Sodium absorption ratio (SAR) 74 – – – 121 –

Note: BDL, below detection limit; –, not analysed.

Table 3Characteristics of effluents of M/s. Leeds Spinning Mills (P) Ltd., Tirupur

Parameter Inlet to ETP Outlet of chemicaltreatment

Inlet to RO RO permeate RO reject NanofilteredRO reject

Nanofiltered dyebath water

pH 9.92 9.08 8.85 7.32 7.09 7.22 10.03Electrical conductivity (mS/cm) 7.09 6.50 6.59 0.44 31.7 40.90 68.7Total suspended solids (mg/L) 41 23 20 2 66 147 11Total dissolved solids (mg/L) 4218 3904 4300 212 23070 33180 56428BOD (mg/L) 360 330 350 7 800 925 450COD (mg/L) 695 563 504 18 3243 4549 1802Total hardness (mg/L) as CaCO3 278 364 404 6 2323 3909 182Ca-hardness (mg/L) as CaCO3 91 364 364 6 2283 3798 81Sulphate (mg/L) 139 133 150 13.5 1019 2803 1219Chloride (mg/L) 1820 1713 1860 103 10510 15430 25257Sodium (mg/L) – – – – 7360 2840 18800Potassium (mg/L) – – – – 328 208 184Percent sodium – – – – 86 99Sodium absorption ratio (SAR) – – – – 67 605.5

Note: –, not analysed.

Table 4Characteristics of effluents of M/s. Amaravathy Textiles, Karur

Parameter Holding tank effluent Inlet to RO RO permeate RO reject NF permeate NF reject

pH 8.9 7.8 6.3 8.2 7.6 7.8Electrical conductivity (mS/cm) 19.30 > 20.0 0.66 > 20.00 > 20.00 > 20.00Total dissolved solids (mg/L) 13770 15396 364 29356 28594 54734BOD (mg/L) 213 – 14 600 180 1320COD (mg/L) 702 – 26 1535 351 3290Total hardness (mg/L) as CaCO3 192 163 3 317 107 518Ca-hardness (mg/L) as CaCO3 115 154 2 307 88 499Sulphate (mg/L) 1419 1486 38 2254 154 5655Chloride (mg/L) 5715 6268 166 12443 14931 22674Sodium (mg/L) 3900 4146 140 13000 12000 22000Potassium (mg/L) 84 86 10 230 300 415Percent sodium 97 98 95 98 98 98Sodium absorption ratio (SAR) 122 194 36 317 229 419

Note: –, not analysed.

Fig. 1. Removal of pollutants using advanced treatment process in different textile dyeing units.

osmosis and/or nanofiltration separation technologies are essentially used to remove theinorganic (mainly) and organic constituents from aqueous solution and non-aqueous solu-tion by membrane (polyamide). The principle followed in all the units are same where asdifferent module such as disc type module and spiral wound module membrane are housedin the RO system. Before charging into RO membrane it is important to remove impuritiessuch as suspended and colloidal impurities of organic and inorganic compounds and dis-solved polyvalent ions to extend the life of the membrane. Almost all the systems attainedcomplete removal of suspended solids. Fig. 1 shows the percent removal of major pollutantssuch as BOD, COD, TDS, total hardness, sulphate and chloride. The industry referred at3.4 has disc type membrane module showed better performance in terms of TDS and otherions removal. The life of the membrane would be reduced due to the absence of preliminarytreatment. The water regenerated using the advanced technology is found good quality andcould be directly used in the dyeing process. A typical schematic diagram of the effluenttreatment plant provided with primary, secondary and advanced treatment technologies forrecycling of wastewater is exhibited in the Fig. 2.

To extend life of RO membranes, flushing the membrane periodically with clean waterand occasional chemical cleaning is required. The pH around 5–6 is desirable to preventboth hydrolysis of membrane and precipitation of calcium carbonate (CaCO3). A modelflow chart of zero discharge scheme for the textile dyeing units is shown in the Fig. 3.Solar evaporation is followed in the units referred above namely M/s. Sivasakthi TextileProcessors and M/s. Leeds Spinning Mills (P) Ltd. Solar evaporation pond is lined with aconcrete layer and arrangements are made to avoid ground water infiltration. An area ofabout 1000 m2 is required per 4 m3 of wastes for solar evaporation. The final dried salts arepacked in polythene bags for final disposal.

3.6. Cost analysis of the water recycling process

Wastewater treatment plant installation and commissioning cost is in the range of INR40–100 lacs, INR 100–200 lacs and INR 200–300 lacs for small (below 300 m3/d), medium

Fig. 2. Typical schematic diagram of advanced wastewater treatment technology for recycling of textile dyeingwastewaters.

(300–600 m3/d) and large (above 600 m3/d) scale textile dying industries. The maintenanceand operation cost is as below:

Chemical cost INR 7–8 m−3

Power cost INR 2–3 m−3

Sludge handling INR 0.75–1 m−3

Manpower INR 1–2 m−3

Filters/cartridges (spares) INR 5–10 m−3

RO/NF membrane maintenance INR 15–20 m−3

Interest and principal paid on the loan (one USD is equal to INR 44) INR 40–50 m−3

Total expenses incurred for the water treatment and recovery is about INR 80/m3 of theeffluent. Due to non-availability of good quality water for dyeing processes in Tirupur, itis purchased from villages 15 km away from the towns and hence the cost of the water isapproximately INR 100/m3 including transportation. Hence, the technology is also eco-nomically viable in the studied area.

Fig. 3. Flow diagram of conceptual zero discharge in textile dyeing unit using advanced wastewater treatment.

The bottlenecks in adopting the technology are high cost of operation for MEE andmaintenance of RO membrane module. Multi effect evaporation is a costly system forconcentration of the effluents before crystallization. It requires more maintenance in termsof consuming more fuel and an average of INR 400 is required per m3 of rejects. Therecovered salt has poor purity and market value of salt is also very less i.e. INR 4 perkg. When the availability of land has become constraint, the MEE would be preferable.A common MEE set-up as joint ventures may be an economical recommendation. Properpreliminary treatments should be followed to reduce the maintenance cost of RO membrane.

4. Conclusion

The study shows the recycling of treated wastewater and zero wastewater dischargeconcept are found technically feasible and economically viable in the textile dying industrieslocated in the area of Tirupur and Karur, Tamil Nadu. The average percent removals of BOD,COD, TDS, Sodium and Chloride in the advanced treatment technology are in the rangeof 88–98%, 91–97%, 80–97%, 96% and 76–97%, respectively. The most attracting partof water recovered from these membranes is its extremely low hardness, which is alwaysdemanded in textile sector for an improved finish and better quality dyeing. The treatmentand maintenance cost INR 80/m3 is cheaper than the water cost INR 100/m3 in Tirupur andKarur areas. Common facility for Multistage Evaporator would be economical.

Acknowledgements

The authors are thankful to Dr. V. Rajagopalan, Chairman, Central Pollution ControlBoard, Delhi for his keen encouragement, Mr. Sunnel Dave, Environmental Engineer forvaluable suggestions and Laboratory members of CPCB, Bangalore for their kind co-operation in sample analysis.

References

APHA. Standard methods for the examination of water and wastewater. Washington DC, USA: American PublicHealth Association; 1995.

Annual Report 2003–2004, Ministry of Textiles, Government of India, 2004, pp. 21–22.Bucklay CA. Membrane technology for the treatment of dye house effluents. Water Sci Technol 1992;25(10):203–9.Central Pollution Control Board. Central laboratory test methods, vols. 1 and 2. Delhi, India: Central Pollution

Control Board; 2001.Ciardelli C, Corsi L, Marcucci M. Membrane separation for wastewater reuse in the textile industry. Resour

Conserv Recycling 2000;31:189–97.Central Pollution Control Board, 2005. Environmental Investigations into the ground and surface water quality

aspects of river Noyyal and performance evaluation of effluent treatment Systems of Tirupur, Tamil Nadu(unpublished report).

Indian Standard 10500, 1991. Indian standard drinking water-specification, Bureau of Indian Standards, NewDelhi.

Rajaguru P, Vidya L, Baskarasethupathi B, Kumar PA, Palanivel M, Kalaiselvi K. Genotoxicity evaluation ofpolluted ground water in human peripheral blood lymphocytes using comet assay. Mutat Res 2002;517:29–37.

Report of Business India, November 2004.Tchobanoglous G, Burton FL. Wastewater engineering: treatment, disposal and reuse/metcalf and eddy. New

Delhi, India: Tata McGraw-Hill Publishing Company Limited; 1995.Vandevivere PC, Bianchi R, Verstraete W. Treatment and reuse of wastewater from the textile wet-processing

industry: review of emerging technology. J Chem Technol Biotechnol 1998;72(40):289–302.