1 TEXTILE WASTEWATER TREATMENT BY A COMBINATION OF ANAEROBIC AND AEROBIC PROCESSES

Abstract In this study, the ability of a combination anaerobic and aerobic processes to treat a denim process wastewater and its application in industrial scale was reported. Laboratory experiments were conducted with the varied hydraulic retention time (HRT) in anaerobic process, i.e. 12, 18 and 24 hours. In the aerobic process, the HRT were 12, and 24 hours, and the SRT (Solid Retention Time) was maintained at 20 days. All experiments performed in room temperature. Each experiment was run for about 90 days. From the laboratory study, it was found that increasing HRT would increase color removal on the anaerobic processes, however no significance different for COD removal. However, the majority of color was removed in the anaerobic process, on the other hand majority of COD was removed in the aerobic process. The combination of anaerobic and aerobic processes was able to reduce COD, BOD and color up to 91, 94 and 96 %, respectively. The color removal was consistently high and visually, no color has been observed in the final effluent. Based on the laboratory results, the industrial scale to treat the wastewater was established. The design flowrate was 20 m3/hour. The biofilter was selected as an anaerobic process with the HRT of 24 hours. The aerobic process was determined extended aeration with the HRT was also 24 hours. The system has been completed on March 2002 and steady state condition was achieved on June 2002 with a performance not much different to the laboratory scale results. Although, a slightly less COD and color removal was observed. From 4 months operation, the COD, BOD and color removal was 87, 93 and 90 %, respectively. At the moment, the treated effluent was recycled back to the denim processing plant and used in washing machines