Operational parameters in HS biofiltration under extreme acid conditions: performance, biomass control, and CO consumption.

This paper reports the treatment of gaseous hydrogen sulfide, HS, in a biotrickling filter (BTF) under extreme acidic pH conditions (≈ 1.2). The effect of adding thiosulfate (NaSO.5HO) to promote biomass growth, feeding low concentrations of ozone to control excess biomass, and the carbon dioxide, CO, consumption by the chemolithoautotrophic consortium were evaluated. The results showed a global removal efficiency over 98.0% with loads of HS > 50 g m h (at 639 ppmv) and a linear relation between HS elimination capacity with the CO consumption rate of around 0.1 gCO/gHS. Supplementing sulfur in the medium with 2 g L thiosulfate resulted in negative effect performance. Respirometry tests proved that the consortium could not utilize this sulfur form at this pH. Additionally, continuous and intermittent O feeding to the BTF in gaseous concentrations of 98 ± 5.4 mg m caused a slight decreased in the performance but the biomass activity in the BTF was only slightly affected allowing a quick performance recovery once O addition was suspended.