Removal of hydrogen sulfide by complete aerobic oxidation in acidic biofiltration

Anaerobic treatment of sulfate-rich wastewater from concentrated rubber latex industry results in high hydrogen sulfide (H2S) in the biogas, which is odorous, toxic, and corrosive to equipment. The effects of retention time (RT) and air mix ratio on the performance and kinetics of the aerobic biofilm reactor in H2S removal were assessed. It was found that H2S removal efficiency increased with increasing air mix ratio and RT. Under a 1:4 biogas-to-air ratio, the system could achieve average removals of 94.7%, 87.3%, 85.6% at RT of 160, 80 and 40 s, respectively. Our biofilter system showed a maximum elimination capacity (ECmax) of 256.4 g/m3/h in our kinetics study. When operated with the acidic wastewater discharged from concentrated rubber factory, the system gave an equivalent performance to that operated with synthetic liquid. Results also revealed that some undesirable methane oxidation had occurred in the biofilter bed. Furthermore, types of the liquid used apparently affected the dominant microbial species in the bed. Although the middle portion of biofilter bed contained fewer microorganisms, H2S could still efficiently be converted to sulfuric acid that could potentially be reused in the concentrated rubber latex industry.