Operational aspects of SO2 removal and microbial population in an integrated-bioreactor with two bioreaction zones.

An integrated-bioreactor, which consisted of a suspended zone and an immobilized zone, was applied to treat gases containing SO2. The removal of SO2 in suspended zone differed slightly from that in immobilized zone. The influences of operational aspects such as SO2 load, temperature, and pH on integrated-bioreactor performance and bacterial community composition were investigated. The synergistic action of the two zones led to effective reduction of SO2, and the total removal efficiencies with the inlet concentration of 91-117 mg/m3, were over 85 % in steady state. Paenibacillus sp. and Lysinibacillus sp. dominated both zones as desulfurization bacteria. Results of polymerase chain reaction-denaturing gradient gel electrophoresis followed by clone library analysis indicated that temporal shifts in bacterial community composition in both zones developed differently. Differences in the concentration of introduced SO2 and supported mode of microorganisms for survival, confirmed that bacterial community composition and abundance significantly differed among individual zones.