Comparison of anoxic sulfide biooxidation using nitrate/nitrite as electron acceptor

Abstract The performance of two lab‐scale Anoxic Sulfide Oxidizing Reactors (ASOR) utilizing diverse electron acceptors was compared to evaluate the loading potential for treating synthetic wastewaters. The nitrite utilizing reactor tolerated very high influent substrate concentrations compared with the nitrate using reactor and displayed better performance at HRT of 2 days and shorter. Under steady‐state denitrifying conditions, the maximal sulfide and nitrite removal rates were 13.53 kg/(m3 days) and 16.31 kg/(m3 days), respectively, while the maximal removal rates with nitrate as electron acceptor were 4.18 kg/(m3 days) and 1.73 kg/(m3 days), respectively. The reactor with nitrite as electron acceptor was able to tolerate high sulfide concentrations up to 1920 mg/L as compared with one using nitrate with influent concentrations up to 580 mg/L. ASORs could endure high nitrite concentrations of 2265 mg/L, while tolerating moderately lower nitrate concentrations of 110 mg/L. The process utilizing nitrite as electron acceptor could tolerate shorter HRTs, as compared with one using nitrate. Superior performance of the nitrite using ASO reactor may be due to more nitrite reactivity. Nitrite might have induced cytochrome production accepting electrons efficiently from sulfide that helped to overcome nitrite toxicity to the denitrifiers involved. Nitrite as an electron acceptor could be a better choice to treat wastewaters containing sulfides. © 2007 American Institute of Chemical Engineers Environ Prog, 2007