A full-scale integrated-bioreactor with two zones treating odours from sludge thickening tank and dewatering house: performance and microbial characteristics

Abstract

A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H2S and NH3 were 1.6–38.6 mg∙m–3 and 0.1–6.7 mg∙m–3, respectively, while the steady-state outlet concentrations were reduced to 0–2.8 mg∙m–3 for H2S and 0–0.5 mg∙m–3 for NH3. Both H2S and NH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.