Biological Decolourization of Simulated Textile Wastewater in UASB Reactor System by Anaerobic Granular Sludge

Abstract

The textile wastewater, containing three acid dyes belonging to different chemical groups; Acid Blue 204 (AB204), Acid Red 131 (AR131) and Acid Yellow 79 (AY79), was studied in UASB (Upflow Anaerobic Sludge Blanket) reactor system from 10 mg/! to 300 mg/! dye concentrations with COD (Chemical Oxygen Demand) of 2000 rag/! as co-substrate. The hydraulic retention time (HRT) of 24 h was maintained. The decolourization achieved was in the range of 73±13.4% to 95%. At 300 mg/! dye level, 89% decolourization was attained. The study suggested that decolourization was due to the combination of processes of adsorption and biodegradation. The UV-Visible spectrum of influents and effluents showed significant changes confirming the degradation of dyes. Acid Blue 204 was decolouriszed by adsorption into microbial granules while other dyes were biodegraded. The COD removal efficiency was over 85% during all dye concentrations indicating no severe toxicity caused to microorganisms by dye mixture. The VFA (volatile Fatty Acids) and alkalinity in effluents were well below 61 mg/1 and 1733 mg/1, respectively, confirming the reactor operated properly. If proper adaptation and maintenance of the UASB reactor system are practiced, the decolourization of textile wastewater containing acid dyes could be achieved via anaerobic microorganisms