1 32 Membranesfor Industrial Wastewater Recovery and Re-use 3.3 The textile industry 3.3.1 Categories of textile processing operations Textile industry processes comprise those which convert natural (e.g. cotton, wool, silk, etc.) and synthetic (e.g. viscose, polyester, acrylic) fibres into fabrics and other products. Four key activities can be identified within this industrial sector (Mattioli et al., 2002): 0 0 0 0 the treatment of raw materials (preparation/production of textile fibres/ yarns), the production of knitted/woven fabrics, the finishing of fabrics (i.e. changing some physical property of the fabric to meet the end use requirement), and production ofproducts (e.g. garments, carpets, etc) from the fabric. In 1998 world trade in textiles was worth approximately $370 billion, or about 6.3% of global merchandise trade (WTO, 1998). USA textile exports account for $19 billion and imports, principally from Mexico and China, around $77b. Around 60% of textile production takes place in Europe (29%) and the Americas, with most of the remaining production taking place in Asia (Stengg, 2001). Within the European Union, which is characterised by a large number of small-to-medium enterprises, Italy accounts for 3 1 % of all textile and clothing manufacturing activities - more than double that of the UK (1 5%), Germany (14%) or France (13%). Most of this activity is accounted for by clothing manufacture. A number of textile manufacturing processes are chemical wet processing operations necessary to properly prepare, purify, colour or finish the product. This results in the production of wastewater whose pollution load arises not only from the removal of impurities from the raw materials but also from the residual chemical reagents used for processing. The freshwater demand is specific to the type of textile processing operation, the type of material or final product and the specific machine or technique used. However, the water demand for wet processing operations is invariably high (Table 3.19), more than 5000 m3 day-l for a large mill. The industry is thus perceived as generating large volumes of effluent which are extremely variable in composition and pollution load, the variability arising from the diversity in the types of transformation processes used and the wide range of chemicals involved. Identifying suitable pollution abatement or water recycling technologies is made difficult by the combining of effluent streams from individual operations, resulting in large variations in effluent chemical composition. Clearly, candidate waste treatment techniques need to be dedicated to individual process effluents, rather than the combined discharge, in order to be reliable and effective. However, this is made extremely difficult in real plants by the sheer number of individual processes contributing to the pollutant load on the combined effluent lndiistrial waters 13 3 Table 3.19 (EPA, 1997) Subcategory Minimum Median Maximum Simple processing 12.5 78.4 275.2 Complex processing 10.8 86.7 276.9 Complex processing plus desizing 5.0 113.4 507.9 Typical water usage, 1 kg' of product, in textile wet processing of woven fabrics stream. Effluent reclamation and reuse thus only becomes viable for individual wastewater streams, where the compositional variability is reduced, and/or in cases where either the discharge consents are stringent (or else the discharge costs high) or the treated effluent has some added value. Both these criteria are pertinent to dyeing wastewater streams, where the possibility exists both to recover chemicals and recycle the treated wastewater (Diaper eta]., 1996). As a rudimentary simplification the USEPA grouped the industry into nine categories in promulgating its guidelines (EPA, 1982). Table 3.20 gives effluent characteristics for the seven most important of categories, these being: raw wool scouring, yarn and fabric manufacturing, wool finishing, o woven fabric finishing, knitted fabric finishing, carpet finishing, and stock and yarn dyeing and finishing. It should be stressed that the figures quoted in Table 3.20 are average figures for complete processes which may entail a number of individual unit operations. Since many textile processing operations are batch, there are broad temporal variations in effluent quality. Variations also arise even within specific individual operations due to the different designs of the actual technology being used. The selection of suitable strategies for pollution abatement and/or water recycling even for specific unit operations is therefore not straightforward, and has to be considered on a case-by-case basis. On the other hand, and in common with most industrial effluent recycling problems: recycling is simplified by segregation of the various waste streams, and membrane technologies offer the most promise of all candidate treatment processes on the basis of the treated water quality being largely independent of the feedwater quality. 3.3.2 Effluents from textile processing unit operations The complete textile manufacturing process involves a number of individual unit operations, each generating effluents of substantially different qualities. For I 34 Membranes for Industrial Wastewater Recovery and Re-use Table 3.20 Textile processing categories and effluent characteristics (EPA, 1978,1997) Parameters Categoriesa 1 2 3 4 5 6 7 BOD/COD BOD (mg/l) TSS (mgil) COD (mg/l) Oil and grease (mg/l) Total chrome (mg/l) Phenol (mg/l) Sulphide (mg/l) Colour AD MI)^ PH Temperature ("C) Water usage (l/kg) Minimum Median Maximum 0.2 6000 8000 30 000 5500 0.05 1.5 0.2 2000 8.0 28 4 12 78 0.29 300 130 1040 4 0.5 0.1 1000 7.0 62 33 - 0.3 5 350 200 1000 0.014 8.0 10 21 - 111 284 657 0.54 650 300 1200 14 0.04 0.04 3.0 325 10 37 5 113 507 0.35 3 50 300 1000 53 0.05 0.24 0.2 400 8.0 39 20 83 3 78 0.3 0.31 300 250 120 75 1000 800 0.42 0.27 0.13 0.12 0.14 0.09 600 600 8.0 11 20 38 - ~ 8 3 47 100 163 557 a Categories description: 1. raw wool scouring: 2. yarn and fabric manufacturing: 3, wool finishing: 4. woven fabric finishing: 5, knitted fabric finishing: 6, carpet finishing: 7, stock and yarn dyeing and finishing. ADMI (American Dye Manufacturers Institute) colour values result from a special procedure for determination of colour in dyeing wastewaters (Allen et al 1972; Little, 1978). example, a woven cotton fabric finishing mill (Fig. 3.29) will typically have processes for preparing the material (which will include some or all of the processes of singeing, desizing, scouring/washing, mercerising and bleaching), colouring it (dyeing and printing) and then fixing these colouring reagents mechanically and/or chemically. The process can thus generate up to six different liquid effluents which are conventionally combined to yield an effluent quality similar to that listed under Category 4 in Table 3.20, and discharged to sewer. However, since some components, and dyes in particular, are not readily removed by conventional municipal wastewater treatment, which is based largely on primary sedimentation followed by biological treatment, surcharges or supplementary consents may be in place for discharges of certain textile effluents. A specific UK example of discharge consents based on colour, and specifically UV absorption, imposed by the regulatory body (the Environment Agency) is given in Section 5.7. Detailed technical descriptions of the most usual operations within the textile industry have been reported by many authors (Cooper, 1978; Nolan, 1972; OECD, 1981), along with effluent water quality data, which generally relates directly to the water at the end of the batch operation which is then discharged. However, many conventional wastewater quality determinants such as COD, TOC, TDS and TSS generally go unreported. Values for other parameters, taken from Cooper (1978), are reported in Table 3.21 along with some water consumption valucs. The values are subject to considerable variation arising lndwtrial waters 13 5 Woven Fabnc Figure 3.29 Manufacturingprocesseuofwovencottonfabricfinishing mills (from Correiaet al 199 5) from differences in design of the specific process technology. For example, beck dying with reactive dyes, at around 38 1 water per kg fabric, can demand almost 10 times as much water as continuous dying with vat dyes (ETBPP, 1997). The data in Table 3.21 thus relate to expected or most probable pollution loads resulting from each wet chemical unit operation in the textile manufacturing process, and do not incorporate the whole range of water qualities that may be encountered in practice. A more comprehensive listing of individual chemical components arising in specific effluent streams is given in Table 3.2 3. Specific wet processes used in textile manufacturing are briefly described below. Non-wet processing techniques, such as singeing, printing, mechanical finishing, weaving and fabrication do not give rise to significant quantities of liquid effluent. Sizing In the transformation of raw materials to textile products sizing is usually the first process in which wet processing is involved. Substances such as starch, modified starch, polyvinyl alcohol, polyvinyl acetate, carboxymethyl cellulose and gums are applied to the warp in order to increase its tensile strength and smoothness. During this operation wastewater results from the cleaning of sizing boxes, rolls, size mixer and sizing area. Their volume is low but, depending on the recipe used, can contain high levels of BOD, COD and TSS (Cooper, 19 78). In the case of 100% synthetic warps sizing, if used, is usually carried out with synthetic polymers. Yarns for use as knitted fabrics are treated with lubricants (mineral, vegetable or ester-type oils) or waxes rather than sizes. 136 Membranesfor Industrial Wastewater Recoveru and Re-use Table 3.21 Pollution loads of textile wet operations (from Cooper, 1978) Desizing Scouring or kiering Mercerising Dyeing Scouring Dyeing Wool Washing Neutralisation Bleaching Nylon Scouring Dyeing Scouring Acrylic Dyeing Final scour Scouring Polyester Dyeing Final scour Viscose Scouring and Dyeing Salt bath Acetate Scouring and Dyeing Cotton Bleaching - 10-13 8.5-9.6 5.5-9.5 5-10 9-14 4.8-8 7.3-10.3 1.9-9 6 10.4 8.4 9.7 1.5-3.7 7.1 - - - 8.5 6.8 9.3 1700-5200 50-2900 90-1 700 4 5-6 5 11-1 800 3 80-2200 4000-11 455 30 000-40 000 28 3 90 1360 368 2190 175-2000 668 500-800 480-2 7 000 650 2832 58 2000 16 000-32 000 7600-17 400 2300-14 400 600-1 900 500-14 100 1129-64448 3855-8315 4830-19267 1 2 4 1-48 30 908 1882 641 1874 1191 833-1968 - - - 3334 4890 1778 3-9 26-43 3-124 2 3 2-3 08 8-300 46-100 16-22 334-835 104-131 3-2 2 SO-67 17-33 50-67 17-33 67-83 2 5-42 17-3 3 17-33 17-33 4-1 3 3 3-SO Desrzrng Desizing removes the substance applied to the yarn in the sizing operation by hydrolysing the size into a soluble form. The methods of desizing, and therefore the wastewater characteristics, vary according to the size used (Table 3.22). Desizing can be as simple as hot washing with detergents for synthetic sizes or more complicated, for example enzyme-augmented degradation, for starch and modified starch (PRG, 1983: Nolan, 1972; OECD, 1981). The pollution load of desizing effluents results from surfactants, enzymes, acids or alkalis used in the size recipes, as well as the sizes themselves (Smith, 1989). The generated wastewater can be the largest contributor to the BOD and TS in a mill eMuent (Nolan, 19 72). as indicated in Table 3.2 1. However, if sizing is carried out using synthetic materials BOD and TSS reductions of up to 90% can be achieved on desizing (Smith, 1989). Scouring Scouring can be performed on both natural and synthetic materials to remove residual reagents. The intensity of the scouring process is dependent on the type of material. Cotton is scoured to remove natural waxes, pectins, spinning oils and other non-cellulosic components using hot alkaline solutions (caustic soda and soda ash) containing detergents or soaps. Herbicides, insecticides, defoliants and desiccants used in the growing of cotton, along with fungicides, such as pentachlorephenols used to prevent mildew during storage and transportation, can also arise in scouring effluents. Cotton scouring waste liquors are thus chemically aggressive and may be toxic. Their solids content, Industrial waters 13 7 Table 3.22 Pollution load from desizing of 50:50 polyesterkotton (PRG, 1983) U e s iz i n g ~ ~ ~ ~ Enzyme starch 6-8 3078 6155 1583 288 Polyvinyl alcohol 6-8 200 400 4029 192 Carboxymethyl 6-8 3 14 400 4349 751 cellulose resulting from the alkali and from impurities in the raw cotton material, is generally high (Table 3.22). Along with desizing, cotton scouring generates very high BOD concentrations. These two processes thus make by far the greatest contribution to effluent BOD in the wet phase processing of cotton goods (Nolan, 1972; Smith, 1989). When synthetic sizes are used desizing and scouring are usually carried out in a single operation. Since synthetic fibres are free from chemical impurities, 100% synthetic fabrics (woven or knitted) require only light scouring in order to remove sizes and lubricants. The process is not normally a significant source of organic or suspended solids pollution. In cases where desizing, scouring and dyeing are performed simultaneously, effluent with an increased pollution load results (Table 3.21). Raw wool scouring is the highest-polluting operation within the textile industry (Table 3.20). The large volumes of effluent and high levels of contaminants generated by this operation have made it an area of the industry of key concern, and much work has been carried out in this area towards abatement of pollution from this process (BTTG, 1992; Nolan, 1972; OECD, 1981). The pollution load results from impurities present in the raw wool, (wax, urine, faeces, vegetable and mineral dirt, and parasite-control chemicals) together with soap, detergent and alkali used during the scouring and washing processes. The use of some of the more onerous organochlorine chemicals in sheep dipping has been restricted by legislation in recent years, but there remain chemicals such as organophosphates that are still used and so arise in raw wool scouring effluents (Shaw, 1994a,b). Due to their non-biodegradability or toxicity, many impurities in scouring effluents (Table 3.23), such as antistatic agents (synthetic fibres), pesticides, cotton waxes and wool grease or wax, can pose problems in the operation of biological treatment systems. Scouring of woollen goods is generally duplicated downstream to remove added substances. These include oils and weaving sizes or lubricants, which are removed using detergents. Bleaching Bleaching removes the natural yellow hue of cotton, increasing its whiteness. This operation is generally required if the finished fabric is to be white or dyed a light colour. It is usually carried out by chemical oxidation with sodium hypochlorite or hydrogen peroxide. Auxiliary chemicals such as sulphuric acid, hydrochloric acid, caustic soda, sodium bisulphite, surfactants and 138 Membranes for lndustrial Wastewater Recovery and Re-use Table 3.23 OECD, 1981) Pollutants from textile wet processing operations (Corrieaet al., 1995; data from Process/fibres Desizing Cotton Linen Viscose Silk Acetates Synthetics Scouring Cotton Viscose Acetates Synthetics Wool (yarn and fabric) Wool (loose fibre) Bleaching Cotton Linen Viscose Jute Acetates Wool Mercerising Cotton Linen Carbonising Wool Fulling Wool Substances Organic (biodegradability)a Inorganic Na+ Ca2+ Na+ NH4+ NH4+ Na+ Na+ Na+ Na+ Na+ NH4+ K+ Ca2+ NH4+ Na+ NH4+ Na+ Carboxymethyl cellulose (SB): Enzymes (A): Fats (SB): Hemicelluloses (A); Modified starches (B): Non-ionic surfactants (A): Oils (SB): Starch (B): Waxes (SR) Carboxymethyl cellulose (SB): Enzymes (A); Fats (SB): Gelatine (A); Oils (SB): Polymeric sizes (NB); Polyvinyl alcohol (A): Starch (B); Waxes (SB) Anionic surfactants (A): Cotton waxes (NB): Fats (SB): Glycerol (B); Hemicelluloses (A): Non-ionic surfactants (A): Peptic matter (A): Sizes (A): Soaps (A): Starch (A) Anionic detergents (B): Fats (SB): Non-ionic detergents (B): Oils (SB): Sizes (B): Soaps (B): Waxes (SB) Anionic surfactants (A): Anti static agents (NB); Fats (SB): Non-ionic surfactants (A): Oils (SB): Petroleum spirit (A): Sizes (B): Soaps (A): Waxes (SB) Anionic detergents (A): Glycol (SB): Mineral oils (SB): Non-ionic detergents (A): Soaps (A) Acetate (B); Anionic surfactants (A): Formate (B): Nitrogenous matter (U): Soaps (A): Suint (A): Wool grease (SB): Wool wax (SB) Formate (B) Oxalate (B) Na+NH4+ Co32-so42- Alcohol sulphates (A): Anionic surfactants (A): Cresols (A): Cyclohexanol (A) Suint (A): Surfactants (A): Wool grease (SB) A13+ Mn2+ S042- Naf C032- Acetate (B); Formate (B): Soaps (A): Suint (A): Wool so42- grease (SB) lndustrial waters 139 Table 3.23 (continued) Process/fibres Substances Organic (biodegradability)” Inorganic Dyeing Cotton Na+Cr3+ C042-F- Viscose Cu2+ N02-022- Linen Sb3+ S2- Sz032- K+ so32- NH4+ S042- Wool Na+ S042- K+ NH++ S032- Cr3+ co32- CU2+ CI- ~13+ Sb3+ Polyamide Na+ C03’- Acrylic Na+ S042- c1- cu2+ NH4+ Polyester Na+ S406’- NH4+ c10- NO3- c1- SO,*- e-Naphthol (A); Acetate (B); Amides ofnaphtholic acid (B): Anionic dispersing agents (A): Anionic surfactants (A); Cationic fixing agents (NB): Chlor- amines (SB): Formaldehyde (A); Formate (B): Nitro amines (SB); Non-ionic surfactants: Residual dyes (NB): Soaps (A); Soluble oils (SB): Sulphated oils (A): Tannic acid (A); Tartrate (B); Urea (B) Acetate (B): Dispersing agents (U); Formate (B): Lactate (B); Residual dyes (NB); Sulphonated oils (A): Tartrate (B) Acetate (B): Formate (B): Polyamide oligeines (U); Residual dyes (NB); Sulphonated oils (A) Acetate (B); Aromatic amines (A): Formate (B); Levelling agents (U); Phenolic compounds (A): Residual dyes (NB); Retardants (U); Surfactants (A): Thioreia dioxide (A) Acetate (B); Anionic surfactants (A): Anti static agents (NB); Dispersing agents (A): Dye carriers (SB); EDTA (NB); Ethylene oxide condensates (U); Formate (B): Mineral oils (SB); Non-ionic surfactants (A): Residual dyes (NB): Soaps (A): Solvents (A) Fireproofing Cotton NH4+ P043- Chlorinated rubber (NB): Melamine resin (NB); Wool Na+ B- Synthetic resin binders (U): Tetrabishydroxymethyl- Sb3+ CI- : Br- phosphonium chloride (U); Thiorea resin (NB) Ti2+ N03-:F- Mothproofing Wool Na+ F- Chlorinated compounds (NB); Formate (B): Waterproofing Cotton Na+ CI- Acetate (B): Dispersing agents (U); Fluoroacrylic Linen K+ esters Wool ~13+ (U): Formate (B): Gelatine (B): Melamine resins (NB): K+: ~13+ Pentachlorphenol laurate (NB) Paraffin wax (NB); Silicone resins (NB): Stearamidemethyl pyridinium chloride (NB): Stearate (B): Titanates (NB) a B, biodegradable: A, biodegradable after acclimatisation: U, unknown; NB, non-biodegradable: SB, slowly degradable. chelating agents are generally used during bleaching or in the final rinses, contributing to the pollution load (Cooper, 1978: Nolan, 1972). Bleaching wastewater usually has a high solids content with low to moderate BOD levels (Table 3.21). The dissolved oxygen content of these effluents may be raised by the decomposition of hydrogen peroxide (Porter, 1990), but residual hydrogen 140 Membranes for Industrial Wastewater Recovery and Re-use peroxide can cause toxicity problems in biological treatment processes (Cooper, 19 78). Only light bleaching, if any, is required when processing 100% synthetic or woollen goods, and the generated wastewater is not a significant source of pollution in such cases (Nolan, 1972). Mercerising Mercerisation is performed almost exclusively on pure cotton fabrics, which are treated by a concentrated caustic bath and a final acid wash to neutralise them. Its purpose is to give lustre and also to increase dye affinity and tensile strength. Mercerisation wastewaters have low BOD and total solids levels but are highly alkaline prior to neutralisation (Cooper, 1978; Nolan, 1972). The low BOD content arises from surfactants and penetrating agents used as auxiliary chemicals (Table 3.21). Carbonising Carbonisation is performed on woollen items to remove traces of vegetable matter. The process can be carried out either in conjunction with raw scouring or at the fabric processing stage, depending on the level of impurities and the end use of the wool (Cooper, 19 78; OECD, 198 1). Carbonising consists of soaking the material in dilute sulphuric acid followed by neutralisation with sodium carbonate. The material is then dried and the brittle cellulosic matter mechanically removed. The generally low levels of organic materials in carbonisation effluents are due to vegetable matter, whilst the acid treatment yields high levels of dissolved solids. Performing carbonisation in conjunction with raw wool scouring leads to a reduction in the total pollution load of the scouring waste stream (OECD, 1981). Fulling Pulling stabilises woollen fabrics and gives them a thicker and more compact appearance. It is carried out with soda ash or sulphuric acid in the presence of detergents, sequestering agents, metallic catalysts and hydrogen peroxide in conjunction with mechanical agitation (Nolan, 19 72: OECD, 1981). The fulling solution is then drained and the treated product extensively washed to remove the remaining chemicals. Fulling wastes in combination with effluents generated by subsequent washing operations present, after raw wool scouring, the largest source of BOD in wool processing wastewaters (Cooper, 1978: Nolan, 1972). Most of the BOD arises from soap, detergents and lubricants and oils added to the wool during the production process. Dyeing Dyeing is carried out to add colour to fabrics or yarn. Identification of generic types of dyeing wastewaters is complicated by the diversity of both the dye chemistry and the operational modes of the dyeing process itself. Although rarely toxic, these wastewaters demand special consideration since they are arguably the most problematic of all textile wastewaters, for a number of reasons: lndustrial waters 141 0 0 they are produced in large volumes (around 100-150 1 kg-l textile product for the average dyeing and rinsing operation), they are not readily biodegradable, such that conventional municipal wastewater treatment plant will generally remove only around 20-30% of colour associated with synthetic dyes, and they require removal to very low levels prior to discharge if consents based on colour are in place. 0 Dyes are generally small molecules comprising two key components: the chromophores, responsible for the colour, and the auxochromes, which can not only supplement the chromophore but also render the molecule soluble in water and give enhanced affinity toward the fibres (Trotman, 1984). A large number of dyes are reported in specialised literature (Colour Index, 1987). These can be classified both by their chemical structure or their application to the fibre type (Table 3.24). Dyes may also be classified on the basis of their solubility: soluble dyes include acid, mordant, metal complex, direct, basic and reactive dyes; and insoluble dyes include azoic, sulphur, vat and disperse dyes. An alternative dye classification that refers to colour removal technologies (Treffry-Goatley and Buckley, 1991) places the various classes of dyes (with respect to their application) into three groups depending on their state in solution and on the type of charge the dye acquires. Each group can be associated with potential colour-removal methods (Table 3.2 5). Complex chemical and/or physical mechanisms govern the adsorption and retention of dyes by fibres. The adsorptive strength, levelling and retention are controlled by several factors such as time, temperature, pH, and auxiliary chemicals (Nunn, 1979; Trotman, 1984; Preston, 1986; Shore, 1990). A large range of substances other than dyes, auxiliary chemicals used in the dyeing process, can be found in a dye effluent at any one time. The effluent composition and colour is further complicated by the fact that both dye fixation rates (Table 3.2 6) and liquor ratios (the volume of dye solution per weight of goods) vary, and different dye classes may be used for a single dyeing operation (Shore, 1990; Horning, 19 78). Moreover, continuous operation yields smaller volumes of more concentrated dyewaste than batch operation, equating to typically a four-fold factorial difference with respect to dye concentration and a 2.5-fold difference in volume (Glover and Hill, 1993), some typical batch process effluent data being given in Table 3.2 7. Chemical finishing Chemical finishing processes include processes designed to change the optical, tactile, mechanical strength or dirt-releasing properties of the textile. Optical finishes can either brighten or deluster the textile (NCDNER, 1995; OECD, 198 1). Softeners and abrasion-resistant finishes are added to improve the feel or increase the ability of the textile to resist abrasion and tearing. Absorbent and soil release finishes alter the surface tension and other properties to increase water absorbency or improve soil release. Physical stabilisation and crease- resistant finishes, which may include formaldehyde-based resin finishes, [...]... 3200 135 3 70 5 70 5600 210 1300 1 470 12 500 15 525 87 3890 0 102 1390 2415 200 450 990 1910 294 1245 198 315 234 215 159 100 78 130 160 315 210 400 255 1120 140 135 150 230 170 400 265 360 300 240 130 49 14 9 5 13 4 26 41 32 9 3 87 34 41 76 39 101 14 258 PH 2028 5.1 1086 4.0 3945 6.8 4.5 1469 1360 5.0 2669 6.6 276 3 5.0 12500 11.2 691 9.1 10900 9.3 2000 3 .7 3945 11.8 170 0 10.2 914 7. 8 77 1 7. 1 396 8.3... ultimately, closed-loop options for industrial water use 146 Membranes for Industrial Wastewater Recovery and Re-use Table 3.29 NSPSs for liquid effluents from cotton woven fabric finishing: 30 day average (1 day maximum) in kg/MTof product (EPA, 19 97) Process BOD COD TSS Sulphide Phenol Chromium pH Simple Complex Desizing 1 .7 (3.3) 1.9 (3 .7) 2.8 (5.5) 26.9 (41 .7) 44.2 (68 .7) 38.3 (59.5) 3.9 (8.8) 6.4(14.4)... Subpart D for the woven fabric includes desizing, Industrial waters 145 Table 3.28 Average process water quality for textile finishing (Mattioli et d., 2002) Parameter Lake Ground Reclaimed" Guide value TSS, mg/l COD, mg/l W abs 420 nm PH Conductivity, pS/cm 78 0 For dyes with molecular weight > 73 9 ~ RO 5 m2 membrane area 22- 27 UF 0.11m2 membrane area 33.2 x lo4 m2,8 1 2 x 10-4m2membrane area 27. 5- 370 34-93 3 .75 -5.0 14.6-39.6 97. 80 UF: polysulphone polysulphone/polymethyl methacrylate membranes 8 5-9 5 12.9-15.4 8.2-15.3 Table 3.34 Recent publications on membranes for dyestuff removal Reference Dye or matrix Removal process Membrane... EPA (199 7) Profile of the textile industry, EPA-3 10-R-9 7- 009 US Environmental Protection Agency, Washington Erswell, A., Brouckaert, C.J and Buckley, C.A (1988) The reuse of reactive dye liquors using charged ultrafiltration membrane technology Desalination, 70 ,1 57- 1 67 156 Membranes for lndustrial Wastewater Recovery and Re-use ETBPP (19 97) Water and chemical use in the textile dyeing and finishing... Buckley, C.A., and Dalton, G.L (1 978 ).Textile size and water recovery by means of ultrafiltration Prog Wat Tech., 10,269-2 77 Hitz, H.R., Huber, W and Reed, R.H (1 978 ) The adsorption of dyes on activated sludge J SOC Dyers and Colourists, 92, 71 Horning, R.H (19 78 ) Textile dyeing wastewaters: characterization and treatment US Department of Commerce, National Technical Information Service (PB-2 8 5 115)... Pre-coag UF NF (NF70, Film-Tec) RO: Film-Tec TW30-1812-50 70 -100% No 90% by RO 0%by UF N insufficient F Marlucci et al (2001); Real effluent Ciardellietal (2001) Sojka-Ledakowicza etal (1998) Analogue and real effluent 0.001 7 PVDF UF, MWCO 70 k Da; Single Osmonics NF, DL4040F SW, element 130-300 Da Film-Tec RO Desalination Systems NF 0.0081 (180 M W C O ) and RO - 98 .7~ 99 .7, NF vs RO Yes (for ROfor reuse)... Colourists, 1 1 2 , 273 -282 Dulio, V (2001) Integrated pollution prevention and control (IPPC) reference document on best available techniques for the textile industry Draft document EPA (1 978 ) Textile processing industry, EPA-625 /77 8-002 US Environmental Protection Agency, Washington EPA (1982) The Textile Mills Point Source Category effluent guidelines, 4 0 CFR Part 410 EPA (199 7) Profile of the textile... ozonation and chemical coagulation Water Res., 27, 174 3-1 74 8 Lin, S.H and Peng, C.F (1996) A continuous treatment of textile wastewater by combined coagulation, electrochemical oxidation and activated sludge Water Res., 30,5 87- 592 Little, L.W (1 978 ) Measurement of color in textile dyeing wastewater Proc Symp Textile Ind Technol., Williamsburg, VA, pp 3 07- 310 LorenCo, N.D, Noucis, J.M and Pinheiro, H.M . 1 874 1191 833-1968 - - - 3334 4890 177 8 3-9 26-43 3-124 2 3 2-3 08 8-300 46-100 16-22 334-835 104-131 3-2 2 SO- 67 17- 33 50- 67 17- 33 67- 83 2 5-42 17- 3 3 17- 33 17- 33. 2669 6.6 276 3 5.0 12500 11.2 691 9.1 10900 9.3 2000 3 .7 3945 11.8 170 0 10.2 914 7. 8 77 1 7. 1 396 8.3 6.5 450 6 .7 691 9.1 the spiralling costs of mains water. Guide values for key water. different qualities. For I 34 Membranes for Industrial Wastewater Recovery and Re-use Table 3.20 Textile processing categories and effluent characteristics (EPA, 1 978 ,19 97) Parameters Categoriesa