In-plant control applications and their effect on treatability of a textile mill wastewater H. Dulkadiroglu, G. Eremektar, S. Dogruel, H. Uner, F. Germirli-Babuna and D. Orhon Istanbul Technical University, Civil Engineering Faculty, Environmental Engineering Department, Ayazaga Kampüsü, 80626, Maslak, Istanbul, Turkey Abstract Water minimization and exploration of the potential for wastewater recovery and reuse are priority issues of industrial wastewater management. They are extremely significant for the textile industry commonly characterized with a high water demand. The study presents a detailed in-plant control survey for a wool finishing plant. A comprehensive process profile and wastewater characterization indicate that process water consumption can be reduced by 34%, and 23% of the wastewater volume can be recovered for reuse. Treatability of reusable wastewater fraction and the effect of in-plant control applications on effluent treatability were also investigated. Keywords Industrial pollution control; in-plant control; textile industry; treatability; wastewater reuse; water conservation; wool finishing Introduction Implementation of in-plant control techniques for textile industries may be tailored for the main purpose of achieving significant reductions in water use, raw material and energy consumption, wastewater production and in some cases even wastewater load (UNEP IE, 1994). In-plant control applications can be grouped under four headings: (i) water minimization (water conservation); (ii) wastewater recovery and reuse; (iii) chemical sub- stitution and (iv) recovery of valuable substances (material reclamation) (Van Veldhuisen, 1991). Significant reductions in water use can be achieved by preventing the unnecessary water consumption practices in textile mills. On the other hand, one of the major in-plant control techniques is the recovery of wastewaters originated from one operation for reuse in a second operation, directly or after being treated. The usage of inefficient washing equipment, poor housekeeping practices, feeding freshwater at all operations requiring water and the application of excessively long washing cycles leading to consumption of unnecessarily high amounts of water are among the reasons of obtaining elevated wastewater volumes (UNEP IE, 1994). Segregating the relatively less polluted wastewater fraction for reuse (Orhon et al., 2000, 2001a) and preventing unnecessary water consumption are observed to generate a stronger wastewater to be treated. Thus, the feasibility of such in-plant control applications must be evaluated by comparing the savings obtained on fresh water demand versus elevat- ed end of pipe wastewater treatment costs together with cost of treating reusable streams, where applicable. In this context, this study involves a comprehensive plant survey including wastewater generation and characterization together with the identification of recoverable streams and the assessment of unnecessary water consumption for a selected wool finishing plant. The systematic approach presented can be adopted for other industrial applications dealing with textile processing. The study also outlines the results of a detailed treatability survey. Biological treatability studies covering the assessment of COD fractionation are conducted on raw wastewater samples obtained before and after the application of proposed appropri- ate in-plant control measures. In this context, the effect of reuse and water conservation Water Science and Technology Vol 45 No 12 pp 287–295 © 2002 IWA Publishing and the authors 287 Downloaded from https://iwaponline.com/wst/article-pdf/45/12/287/424839/287.pdf by guest on 09 November 2018