(752d) A Novel up-Flow Inner-Cycle Anoxic Bioreactor (UIAB) System for the Treatment of Sulfide Wastewater and Purification of Biogas

Anaerobic digestion is one of common treatment processes for the organic wastewater disposal, and usually produces methane-rich biogas. Biogas from anaerobic digestion always contains hydrogen sulfide, which is highly toxic, corrosion and malodorous. Biogas desulfurization is essential for its purification processes before utilization. Biological desulfurization process is a method of eliminating sulfide in aqueous by autotrophic colorless sulfide-oxidizing bacteria. Hydrogen sulfide is adsorbed by alkaline solution, and is chemically transformed into sulfide.

In this paper, an up-flow inner-cycle anoxic bioreactor with a novel three phase separator was designed and implemented for the treatment of sulfide wastewater. The sulfide in wastewater could be converted to element sulfur by sulfide oxidizing bacteria, and recovered by simple precipitation. When the oxidation-reduction potential (ORP) was controlled at -100mV, 91.3% of sulfide could be oxidized to element sulfur. To achieve high sulfide removal rate and sulfur conversion yield, the pH of influent should be controlled at the range from 7.0 to 8.0. The optimal desulfurization process was carried out at 400 mmol·L^-1·d^-1 sulfide loading rate and 120 min hydraulic retention time (HRT). The sulfide removal rate was approximately 95.2% and element sulfur conversion rate was above 90.3%. These results demonstrated that the novel up-flow inner cycle anoxic bioreactor system could be regarded as not only the enhancement of sulfide oxidation process but also one important purified stage for biogas, which would be an efficient and economic supplement method for the treatment of sulfide wastewater from gas purification.