Implementation of Chemical Precipitation, Bio-oxidation and Membrane System in Textile Industry - A Case Study

The paper presents a case study of textile dyeing industry on implementation of full-scale effluent treatment plant (ETP). The industry in compliance with the protection of the surface water source implemented chemical precipitation, bio-oxidation followed by membrane system for resource recovery in terms of renovated water and raw material (sodium chloride) for process reuse. The dye bath effluent and wash water generated are combined together and treated through chemical precipitation, activated sludge process, media filtration and activated carbon adsorption for removal of major pollutants. The removal in terms of suspended solid (SS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are in the range 80-84, 86-90 and 80-86%, respectively. The tertiary treated effluent after microfiltration followed by advanced treatment comprising ultrafiltration and two stage reverse osmosis system achieve a permeate recovery of 84-90% and recycled for process use. The 10-14% rejects from the reverse osmosis system is routed through nanofiltration for recovery of sodium chloride (brine solution) and reuse in process for dye bath preparation. The final rejects 5-7% is dried through solar evaporation, and are packed in Polythene bags and transported for final disposal in TSDF. The capital and O&M costs of treatment are in the range Indian Rupee (INR) 0.44-0.50 Lakhs and 70-80 Rs. Per m(3) of design flow, respectively (1USA$ = INR 49.0650).