Treatment of Textile Wastewater by a Coupling of Activated Sludge Process with Membrane Separation

Abstract

This research was conducted to investigate the capability of a coupling of activated sludge and microfiltration processes with backflushing technique to reduce organic carbon and color in textile wastewater. In this study, the optimum condition of membrane operation was obtained at 0.88 m/s cross-flow velocity (CFV) and 0.4 bar transmembrane pressure (TMP). On the other hand, the optimum condition of backflushing technique was obtained at 1.6 bar pressure applied for 1 second at 1.5-minute interval. With this optimum condition, the flux was relatively stable at 5.04 L/m².h for all SRT. At steady state, the effluent COD decreased with increasing SRT. The COD removal was more than 82 % and color removal was more than 95 %. The microorganisms involved in the system were found to be slow-growing microorganisms. Therefore, the coupling of activated sludge and membrane separation processes successfully proceeded to treat textile wastewater. Complete solids removal as well as a significant degree of organic and color removal was achieved. Sludge production was also low amounting to less than 0.2 g dried cells/ g COD removed. Thus, the treatment of unsettled textile wastewater to a tertiary effluent quality in a single unit process was made possible.