A chemical substitution study for a wet processing textile mill in

a b s t r a c t Wet processing textile industry has many different processing stages (dyeing, sizing, de-sizing, scouring, softening, etc.). Many chemicals currently used in the wet processing textile industry affect the amount and the type of waste produced and their influence on the aquatic life of the receiving stream. One of the critical steps in pollution prevention studies is auditing the use of chemicals and making the necessary chemical substitutions. This chemical substitution study was conducted on one of the major textile factories in Turkey with a capacity of 20,000 tons of denim fabric per year. During this study, chemical consumption level, receipts applied, environmentally problematic and alternative chemicals were examined. Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques (BAT) for the Textiles Industry was accepted as main reference document and also related case studies were examined. According to the study, over 70% reduction in sulphide, which is very toxic to aquatic life, was achieved by replacing sulphur dyestuff with low sulphide content. By replacing an alternative complexing agent, the mill not only prevented the 3100 kg/month COD load to the wastewater treatment plant (WWTP), but also obtained more biodegradable wastewater generated during production. On the other hand, some of the chemical substitution options were on progress or dropped

Biosorption of Ni(ii) and Pb(ii) by Phanerochaete chrysosporium from a binary metal system – kinetics

The biosorption kinetics of Ni(II) and Pb(II) by the resting cells of a lignolytic white-rot fungus, Phanerochaete chrysosporium, from a binary metal system were investigated. Kinetic studies revealed that biosorption takes place in two stages: a rapid surface adsorption, within the first 30 min, and a slow intracellular diffusion till the end of the 3 h contact time. In the first minutes of contact solution pH decreased sharply, parallel to the fast metal uptake, probably because of the protons released by the biosorbent. As sorption equilibrium was reached, solution pH also reached an equilibrium level. Metal biosorption capacities increased as the initial metal concentrations (Ci) increased, independent of initial pH (pHi) and generally the metal with higher Ci had a higher uptake capacity. The results also show that some portion of the metal ions sorbed by P. chrysosporium was readily released to solution with a decrease in pH. At equilibrium, the maximum total metal uptake of P. chrysosporium was 109.5 mg/g and was reached at pHi 5. Under these circumstances Ni(II) and Pb(II) uptake capacities were 55.9 mg Ni/g and 53.6 mg Pb/g, respectively. WaterSA Vol.27(1) 2001: 15-2

Formation of chlorination by-products. in waters with low SUVA-correlations with SUVA and differential UV spectroscopy

The formation of THMs and HAAs after chlorination of bulk water fractions of low-SUVA (specific UV absorbance) surface waters was investigated, and the applicability of SUVA and differential UV spectroscopy for monitoring THMs and HAAs in such waters was evaluated. Samples from two reservoirs were fractionated employing XAD-8, XAD-4, MIEX (R) resin and granular activated carbon adsorption. A total of 83 bulk water NOM fractions (i.e., the remaining solutions after contact with the adsorbent or resin at various doses) were obtained and chlorinated. The majority of NOM in both waters was found to have average molecular weights < 2000 Da and SUVA values < 2 L/mg C m, indicating that NOM in the tested waters contained dominantly lower molecular weight fractions and low aromaticity. SUVA did not correlate well with the formation and speciation of THMs and HAAs, suggesting that SUVA does not capture the reactive sites on NOM moieties responsible for DBP formation in low-SUVA waters. Similarly, no correlations were found among THMs/ HAAs formations and differential UV spectroscopy, indicating the formation of DBPs independent of destruction in UV-absorbing sites. In all fractions, concentrations of THMs were higher than those of HAAs. Chlorinated DBP species were dominant over brominated ones due to low bromide concentrations. The results overall suggested that low- or non-UV-absorbing NOM moieties play important roles in the formation of DBPs in waters with low SUVA, low DOC and low bromide levels. (c) 2007 Elsevier Ltd. All rights reserved

Nanofiltration and Reverse Osmosis for Reuse of Indigo Dye Rinsing Waters

WOS: 000277727100004A membrane based treatment strategy was developed for the possible recycling of rinsing wastewater from indigo dyeing to the process itself. Performances of three different nanofiltration (NF) (NF 270 and NF 90, Dow Film Tech, USA and NF 99, Alfa Laval, Denmark) and two different reverse osmosis (RO) (HR 98 PP and CA 995 PE, Alfa Laval, Denmark) membranes were investigated with wastewater collected from the first post-rinsing tank of indigo dyeing process of a denim manufacturing plant. Dead-end microfiltration with a 5 mu m filter was employed to remove coarse particles and minimize fouling of further NF and RO membranes. For NF and RO, a lab scale plate-and-frame membrane module was operated at a pressure of 5.07bar and at a 0.62m/s cross-flow velocity. The permeate quality from all the tested NF and RO membranes was acceptable for reuse in terms of COD and color. However, only the permeate from HR 98 PP RO and NF 90 membranes were with an acceptable conductivity. On the other hand, NF 270 membrane was superior to all the other NF and RO membranes in terms of the permeation rate. Flux declines obtained for all membranes were higher than 50% but fouling was not considerable and completely reversible. The good performance of NF 270 in terms of permeate quality (permeate conductivity, color, and COD values were 4.3mS/cm, 8 Pt-Co, and 87mg/L, respectively) together with a higher flux makes this membrane preferable over the other membranes to recycle denim textile rinsing wastewaters.Scientific and Technological Research Council of Turkey [CAYDAG-105Y088]The authors wish to express their gratitude to the Scientific and Technological Research Council of Turkey for funding the project (CAYDAG-105Y088) of which this study forms a part and also to METU Research Fund. Dow FilmTec (Minneapolis) and Alfalaval (Denmark) are thanked for supplying the membrane samples. Special thanks are extended to the textile mill administration for their technical support and for providing wastewater samples

Effects of bromide ion and natural organic matter fractions on the formation and speciation of chlorination by-products

The impacts of bromide concentration and natural organic matter (NOM) characteristics on the formation and speciation of disinfection by-products (DBPs) in chlorinated NOM fractions were investigated. A total of 20 bulk water NOM fractions with a wide range of specific ultraviolet (UV) absorbance (SUVA(254)) values were obtained from a source water employing XAD-8 or XAD-4 resin adsorption in completely mixed batch reactors. SUVA was not a good predictor of DBP [trihalomethanes (THMs), haloacetic acids (HAAs), and adsorbable organic halogens (AOX)] formation and speciation. The destruction in the UV(254) absorbance from chlorination did not correlate with DBP formation at any bromide level. NOM moieties which do not absorb UV light at 254 nm significantly contributed to DBP formation. Mass balance calculations on halogens using THMs, HAAs, and AOX data indicated that significant amounts of DBPs (> 54% of AOX) other than THMs and HAAs were formed in NOM fractions with 60-110 mu g/L bromide concentration. The relative occurrence of such other halogenated by-products decreased with increasing bromide concentrations up to 500 mu g/L level. NOM in the studied water was more susceptible to the formation of brominated THM species as opposed to brominated HAAs. At constant dissolved organic carbon concentration, chlorine dose and pH, increasing bromide concentrations in NOM fractions increased the total concentrations of DBPs and resulted in a shift toward the formation of brominated species. Further, increasing bromide concentrations increased the spectrum of detected species (i.e., occurrence of all nine HAAs) and provided a competitive advantage to THM and HAA precursors in NOM over precursors of other DBPs

Removal of disinfection by-product precursors by UF and NF membranes in low-SUVA waters

The performance of ultrafiltration (UF) and nanofiltration (NF) membranes on disinfection by-products (DBPs) precursor removal in a surface water having low-to-medium dissolved organic carbon (DOC) and specific ultraviolet absorbance (SUVA(254)) levels was evaluated. While higher molecular weight (HMW) DOC fraction was successfully rejected (> 90%), lower molecular weight (LMW) fraction could be removed only 1.5-30% by the tested four different membranes (two UF and two NF). This finding suggested that although NF and UF membranes with pore sizes of <= 1000 Da are highly effective on the removal of HMW NOM from waters having low-to-medium DOC and SUVA(254) levels, such membranes are not effective in these waters in rejecting LMW fractions (i.e., < 2000 Da). NF membranes provided THM and HAA formation reductions above 90%. However, DOC and UVA(254) rejections could not be directly linked to DBP formation reductions by the tested membranes. Due to higher rejection of DOC than the bromide ion in UF and NF separation, Br/DOC ratio increased which further increased the relative occurrence of brominated THM and HAA species over chlorinated ones. (c) 2008 Elsevier B.V. All rights reserved