Advanced treatment of textile wastewater towards reuse using a membrane bioreactor

Abstract

The aim of this work was to quantify the performance of a membrane bioreactor (MBR) for the treatment of textile wastewater, and to investigate its capability to achieve a water quality meeting reuse criteria. A laboratory-scale MBR unit was fed with textile wastewater originating from a polyester finishing mill. Removal capacity was examined at VLRs ranging between 0.35 and 3.6 g/(l day). In addition, the effect of nutrient addition was studied. COD removal was found to vary between 60 and 95% with reduced COD levels at lower VLRs tested. Nutrient addition slightly enhanced effluent quality. Sludge yield obtained were between 0.01 and 0.1 gMLSS/gCOD removed. At similar sludge loading rates specific sludge production rates were approximately 50% higher when nutrients were added. A distinct relationship between sludge growth and colour removal could be observed. Above an sludge growth rate of 0.3 g/(l day), colour removal was above 87% for all wavelengths examined. If reuse of MBR treated wastewater is intended, additional polishing steps must be considered as MBR effluents did not reach the required quality for water reuse. In order to upgrade MBR effluent, nanofiltration as a post-treatment was suggested.