Impact of SRT on the Performance of Sequential Sulfate Reducing Anaerobic and Sulfide Oxidizing Aerobic Membrane Bioreactors Treating Textile Industry Wastewater

This study aims at evaluating the impact of SRT (infinite, 60 and 30 days) on the treatment and filtration performances sequential sulfate reducing anaerobic and sulfide oxidizing aerobic MBRs treating synthetic textile industry wastewater. The influent COD, dye and sulfate concentrations were kept constant at 2000, 200 and 1000 mg/L, respectively. The decreased SRT caused significant and partial decreases in COD oxidation and sulfate reduction, respectively, due to decrease of biomass concentration. Almost complete decolorization was attained in the AnMBR and a slight recolonization was observed in the AeMBR. Sludges filterabilities were assessed with capillary suction time, specific resistance to filtration and supernatant filterability tests. Compact and non-porous cake layer formed in the AnMBR. Metal-sulfide and Ca-P precipitates were detected in the cake layers of AnMBR and AeMBR, respectively, by SEM-EDS analyses. Desulfomonas thiophila and Thioalkavibrio sulfidiphilus were dominant sulfate-reducing and sulfide oxidizing bacteria in AnMBR and AeMBR, respectively.