Simultaneous removal of sulfide, nitrogenous compounds and organic carbon by anoxic attached-growth bioreactor

By decreasing hydraulic retention times to increase substrates loading rates under anoxic conditions, an attached-growth bioreactor packed with porous sponges was started to treat the wastewater contaminated by sulfide, nitrate, nitrite and organic carbon. The influent concentrations of sulfide, nitrate-nitrogen, nitrite-nitrogen and TOC were 200 mg/L, 52.5 mg/L, 20 mg/L, 20 mg/L and relevant removal efficiencies were 99%, 99%, 95.5% and 80% respectively. The simultaneous removal of nitrogenous compounds, sulfide and organic carbon was achieved by the desulfurization and denitrification process. With increasing of the substrate loading rates, the adaptabilities of nitrate and nitrite to the influent shock load decreased. The adaptability of nitrate to the shock load was better than that of nitrite. Compared with the impact on the bioreactor brought by the increasing of the influent shock load, the destruction of anoxic environment had greater influence on the degradation of nitrate and nitrite. 60% of the removed sulfide was converted to sulfur by microorganisms. The dominant reaction of autotrophic denitrification occurred together with the heterotrophic denitrification whose percent was 21.76%.