Sulfide-based mixotrophic denitrification for treatment of sulfur, nitrogen and carbon-contaminated wastewater

Wastewater contaminated by sulfur, nitrogen and carbon compounds was treated by sulfide-based denitrification process in an expanded granular sludge bed packed with porous sponge. In influent, nitrate and nitrite served as electron acceptors, while sulfide and organic carbon served as electron donors. Both sulfide-based autotrophic denitrification and heterotrophic denitrification were found in the bioreactor. The percentage of heterotrophic denitrification was 36.5%, and the removal rates of sulfide, nitrate, nitrite and organic carbon were 99%, 99%, 95.5% and 80% respectively, which actualized the simultaneous mixotrophic denitrification and desulfurization. The effect factors such as organic carbon category, organic carbon loading rate and nitrite loading rate were also investigated. The 50 mg Cl(-1)d(-1) of glucose and 25 mg Cl(-1) d(-1) acetate sodium were found good for sulfide-based denitrification, while the suitable loading rate of nitrite was 50 mg Nl(-1)d(-1).