NO and N2O accumulation during nitrite-based sulfide-oxidizing autotrophic denitrification

promoted by the low ratio of S/N. N2O accumulation resulted from the combined action of H2S and free nitrous acid (FNA). Both H2S and FNA could inhibit N2O reductase activity. The two stages that HS- oxidized to S0 and S0 oxidized to SO42- proceed successively and could be distinguished by pH variation. Thiobacillus?Ottowia ?Thiovirga presented the functional genera to remove sulfide and nitrite in this studied reactor.