NOVELTY - A biological desulfurization equipment has injection portions (173-175) and static mixers (181-183) arranged at downstream vicinity of injection portion. To-be-processed gas and oxygen-containing gas are introduced into microorganism desulfurization tower (1) filled with filler (10) which supports aerobic sulfur-oxidizing bacteria. Hydrogen sulfide in to-be-processed gas is biologically oxidized and desulfurized. The injection portion injects 3 times or less of oxygen-containing gas with respect to stoichiometric amount required for oxidation.    USE - Biological desulfurization equipment is used for desulfurizing to-be-processed gas (claimed), such as biogas (generated by methane fermentation of organic waste, such as livestock-farming and human waste) used as fuel.    ADVANTAGE - The biological desulfurization equipment carries out homogeneous and safe mixing of methane gas and air.    DETAILED DESCRIPTION - A biological desulfurization equipment has an injection portion(s) (173-175) for injecting an oxygen-containing gas, and static mixer (181-183) arranged at downstream vicinity of the injection portion. To-be-processed gas and oxygen-containing gas are introduced into microorganism desulfurization tower (1) filled with a filler (10) which supports an aerobic sulfur-oxidizing bacteria. The tower is provided with an introduction piping (11) which introduces methane gas and to-be-processed gas containing hydrogen sulfide (0.5 vol.% or more) to the lower portion. Hydrogen sulfide is biologically oxidized and desulfurized. The injection portion injects three times or less of oxygen-containing gas with respect to stoichiometric amount required for oxidation of hydrogen sulfide.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of the biological desulfurization equipment. (Drawing includes non-English language text)    Microorganism desulfurization tower (1)    Filler (10)    Introduction piping (11)    Injection portions (173-175)    Static mixers (181-183)