Biological techniques for the removal of gaseous pollutants such as hydrogen sulfide (H2S) have proved to be effective, environmentally friendly, and economically viable. However, when high concentrations of H2S are treated, the process is severely restricted by the oxygen deficit in the liquid phase. The oxygen transfer efficiency provided by a membrane diffuser is evaluated under typical pressure and salinity conditions used for the biological treatment of H2S in biogas. The optimal operating parameters for enhanced oxygen transfer were determined. The addition of pure oxygen with a membrane diffuser to increase the oxygen transfer rate and the use of a nonaqueous phase to improve oxygen transfer in a bioscrubber system are also evaluated.