Removal of Hydrogen Sulfide from Swine-Waste Biogas on a Pilot Scale Using Immobilized Paracoccus versutus CM1.

Hydrogen sulfide (H 2 S) is a toxic and corrosive component that commonly occurs in biogas. In this study, H 2 S removal from swine-waste biogas using sulfur-oxidizing Paracoccus versutus CM1 immobilized in porous glass (PG) and polyurethane foam (PUF) biofilters was investigated. Bacterial compositions in the biofilters were also determined using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The biofilters were first tested on a laboratory scale under three space velocities (SV): 20, 30, and 40 h -1 . Within 24 h, at an SV of 20 h -1 , PG and PUF biofilters immobilized with P. versutus CM1 removed 99.5% and 99.7% of H 2 S, respectively, corresponding to the elimination capacities (EC) of 83.5 and 86.2 gm -3 h -1 . On a pilot scale, with the horizontal PG- P. versutus CM1 biofilter operated at an SV of 30 h -1 , a removal efficiency of 99.7% and a maximum EC of 113.7 gm -3 h -1 were achieved. No reduction in methane content in the outlet biogas was observed under these conditions. The PCR-DGGE analysis revealed that Paracoccus, Acidithiobacillus , and Thiomonas were the predominant bacterial genera in the biofilters, which might play important roles in H 2 S removal. This PG- P. versutus CM1 biofiltration system is highly efficient for H2S removal from swine-waste biogas.