Sulfate reduction and filtration performances of an anaerobic membrane bioreactor (AnMBR)

Sulfate-reducing bioprocesses can be used in the treatment of sulfate-containing industrial effluents including mining, metallurgical and food industries. Although membrane bioreactors (MBRs) have been studied for anaerobic wastewater treatment, sulfidogenic anaerobic MBRs (AnMBRs) received little or no attention. The aim of this study was to evaluate the performance of sulfate-reducing AnMBR and investigate the membrane foulants and filtration characteristics. Sulfate reduction and COD oxidation efficiencies exceeded 90% when the reactor was fed with a synthetic sulfate-rich (2000 mg/L) wastewater with COD/sulfate ratio of 0.75. Long-term filtration performance was evaluated using several filterability tests. Deposition of high molecular weight soluble organics and S, Si, Fe, Cu, Na, and Mg were detected in the cake layer. The formation of metal-sulfide precipitates was the main reason for heavy metal deposition on the membrane surface. Desulfovibrio-like sulfate reducing bacteria was detected in the bioreactor. Results showed that sulfate-reducing AnMBR offers potential for real scale applications.