The schematic of a bioscrubber is shown in Fig. 9.10. Removal of hydrogensulfide in a bioscrubber is achieved in two stages. The first-stage involvesphysical or chemical absorption of the pollutant in a liquid stream (normallywater), followed by the biological treatment of this liquid in a separate bioreactor unit. Aerobic bioscrubbers have been reported in the literature to yieldhigher hydrogen sulfide removals than other biological processes. For anaerobic gases like biogas, similar systems can perform successfully taking intoaccount the limitations of oxygen supply. Besides, compared to pure absorption-based techniques, like liquid redox systems (iron cheleates); bioscrubbersmay serve as a good eco-friendly alternative (van Groenestijn 2001) . Asdescribed previously, chemical absorption based on iron chelated solutionsneeds one step only to regenerate the liquid absorbent, while in the case ofbioscrubbers; regeneration can easily be achieved by the activity of microorganisms like Acidithiobacillus ferrooxidans.