Hydrogen sulfide removal from biogas by biotrickling filter inoculated with Halothiobacillus neapolitanus

Hydrogen sulfide (H2S), a highly corrosive gas, is found in biogas due to the biodegradation of proteins and other sulfur containing organic compounds present in feed stock during anaerobic digestion. The presence of H2S is one of the biggest factors limiting the use of biogas. It should be removed prior to application of biogas in an electric generator or industrial boiler. The present research evaluated the performance of biotrickling filter inoculated with Halothiobacillus neapolitanus NTV01 (HTN) on the H2S removal from synthetic biogas. HTN, isolated and purified from activated sludge, is a sulfur oxidizing bacteria able to degrade H2S and thiosulfate to elemental sulfur and sulfate, respectively. Operational parameters in a short term operation were varied as following; gas flow rate (0.5-0.75 LPM); EBRT (40-120 s); the inlet H2S concentrations (0-1500 ppmv); liquid recirculation rate (3.6-4.8 L/h). EBRT showed a greater effect to the removal efficiency than increasing H2S concentration. Longer EBRT resulted higher removal efficiency. The changes of liquid recirculation rates did not significantly affect the removal efficiency. In long term operation, the gas flow rate and liquid recirculation rate were fixed at 0.5 LPM (120 s EBRT) and 3.6 L/h; and H2S concentrations were varied (0-2040 ppmv). The maximum elimination capacity was found as 78.57 g H2S/m3 h, which had greater performance than the previous studies.