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
