바이오가스에 포함된 고농도 황화수소의 효율적 제거를 위한 미생물반응기

Abstract

A two-stage bioreactor system using sulfur-oxidizing bacteria was studied to abate high strength hydrogensulfide (H2S) from biogas. The two-stage bioreactor consisted of a H2S absorption column (0.5 L) and a microbialoxidation column (1 L) in series, and the liquid medium was continuously recirculated through the columns. Theobjectives of this study were to determine the feasibility of the bioreactor for biogas desulfurization and toinvestigate the effect of the medium circulation rate on the system performance. An averaged concentration of H2Sintroduced to the bioreactor was 530 ppm, corresponding to an overall loading rate of 44.4 g/m3/hr. During theinitial 20 days period at the medium recirculation rate of 8 reactor volumes per hour (12 L/hr), the dissolved oxygen(DO) concentration in the oxidation column was 6 mg/L, while the DO in the absorption column was 0.5 mg/Lshowing that the oxygen contents of the biogas stream was not altered. Because of the biological oxidation of H2Sin the oxidation column, the sulfate concentration increased from 200 mg/L to 5,600 mg/L in the liquid medium. The removal efficiency of H2S was greater than 99% in the initial operation period. After the initial period, themedium recirculation rate between the two columns was stepwise changed eight times from 1.0 to 40 vol/hr (1.5~60 L/hr). At the recirculation rate of faster than 4 vol/hr, the H2S removal efficiencies were found to be high, but theefficiency declined at the lower recirculation rates than the threshold.