Biodesulfurization of landfill biogas by a pilot-scale bioscrubber: Operational limits and microbial analysis

Biogas serves as a crucial renewable energy vector to ensure a more sustainable energy future. However, the presence of hydrogen sulfide (H₂S) limits its application in various sectors, emphasizing the importance of effective H₂S removal techniques for maximizing its potential. In the present study, the limits of a pilot-scale bioscrubber for biogas desulfurization was study in a real scenario. An increase in the superficial liquid velocity resulted in significant improvements in the H₂S removal efficiency, increasing from 76 ± 8% (elimination capacity of 6.2 ± 0.5 gS-H₂S m^-3 h^-1) to 97.7 ± 0.5% (elimination capacity of 8 ± 1 gS-H₂S m^-3 h^-1) as the superficial liquid velocity increased from 50 ± 3 m h^-1 to 200 ± 8 m h^-1. A U_SL of 161.4 ± 0.5 m h^-1 was able to achieve outlet H₂S concentrations as low as 3 ± 1 ppm_v (H₂S removal efficiency of 97 ± 1%) for 7 days. High superficial liquid velocity favoured the aerobic H₂S oxidation reducing the nitrate demand. The maximum EC reached throughout the operation was 50.8 ± 0.6 gS-H₂S m^-3 h^-1 (H₂S removal efficiency of 96 ± 1%) and a sulfur production of 60%. Studies in batch flocculation experiments showed sulfur removal rates up to 97.6 ± 0.9% with a cationic flocculant dose of 75 mg L^-1. Microbial analysis revealed that the predominant genus with sulfo-oxidant capacity during periods of low H₂S inlet load was Thioalkalispira-sulfurivermis (61-69%), while in periods of higher H₂S inlet load, family Arcobacteraceae was the most prevalent (11%).