A chemical substitution study for a wet processing textile mill in Turkey Ertan Ozturk, Ulku Yetis, Filiz B. Dilek, Goksel N. Demirer * Department of Environmental Engineering, Middle East Technical University, Ino ¨nu ¨ Bulvari, 06531 Ankara, Turkey article info Article history: Received 18 May 2007 Received in revised form 1 May 2008 Accepted 3 May 2008 Available online 20 June 2008 Keywords: Pollution prevention Chemical substitution Textile industry Integrated pollution prevention and control abstract 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 ex- amined. 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 waste- water 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. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction In textile processing industry, large amount of water is used during dyeing and finishing processes. While Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Avail- able Techniques (BAT) for the Textiles Industry indicates that water consumption varies from 70 to 250 l/kg fabric depending on the techniques applied [14,35], many sources from South Africa in- dicated that the specific water intake for the textile industry varies from 95 to 400 l/kg fabric depending on the type of processes used and water efficiency [2–4]. While 20–230 m 3 of water is needed to produce 1 ton of textile fabric in Turkish factories [5]. The total quantity of chemicals used in textile mills varies from 10% to over 100% of the weight of the cloth [6] and the chemical loads are generated mainly due to the residues from preparation, dyeing, finishing, sizing, and other operations. Therefore, the amount of water discharged and the chemical load of textile effluents are the major environmental concern in the textile industry [7,8]. Textile manufacturing generates solid, hazardous and air pol- lutant wastes, on the other hand, wastewater, by far, is the largest waste stream. For the textile industry, in general, the effluent is highly-colored, high in BOD and COD, has a high conductivity and is alkaline in nature [3,6,9–14]. These factors combine to present numerous operational problems in municipal wastewater treat- ment works, which are biological processes and not intended for the breakdown of complex organic molecules. The presence of metals and other dye compounds inhibits microbial activity and in some cases may cause failure of biological treatment systems [13]. Therefore, substitution of chemicals having lower hazard potential for chemicals having higher hazard potential should be a main fo- cus for pollution prevention [7,8]. Chemical (Material) Substitution is defined as ‘‘the replacement or reduction of hazardous substances in products and processes by less hazardous or non-hazardous substances, whilst achieving an equivalent functionality via technological or organizational mea- sures’’ [15–18]. Many studies indicate that material or chemical substitution can bring pollution prevention and increase in cost effectiveness to- gether [19–22]. Admittedly, treatment costs can be reduced by in- troducing more biodegradable chemicals in production lines [8]. Literature indicates that pollution prevention by replacing sizing agents [6,9,14,23], surfactants [1], urea [24], solvent [25–28], acid [29], and reducing agents [30] with environmentally friendly chemicals can be achieved. In this study, a wet processing textile mill in Turkey was in- vestigated. The average annual capacity of the mill is 20,000 tons of ring yarn and 40 millions meters of denim fabric. In all wet pro- cesses, the ground water is used and the daily average water con- sumption of the mill is about 3500–5000 tons. The total monthly consumption of the chemicals is about 1000 tons and over 100 * Corresponding author. Tel.: þ90 312 210 5867; fax: þ90 312 210 2646. E-mail address: goksel@metu.edu.tr (G.N. Demirer). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro 0959-6526/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jclepro.2008.05.001 Journal of Cleaner Production 17 (2009) 239–247