NOVELTY - Removal of hydrogen sulfide from hydrogen sulfide-contaminated energy production gas stream (1) containing methane involves adding an aqueous nitrate solution to the hydrogen sulfide-contaminated energy production gas stream in aqueous biofilter system (10), contacting the gas stream with microorganisms of humidified biofilm, oxidizing portion(s) of hydrogen sulfide in the hydrogen sulfide-contaminated energy production gas stream using microorganisms under anoxic conditions to produce hydrogen sulfide-depleted energy production gas stream.    USE - Removal of hydrogen sulfide from hydrogen sulfide-contaminated energy production gas stream containing methane using aqueous biofilter system (claimed).    ADVANTAGE - The method enables efficient and economical removal of hydrogen sulfide from hydrogen sulfide-contaminated energy production gas stream containing methane with high quality.    DETAILED DESCRIPTION - Removal of hydrogen sulfide from hydrogen sulfide-contaminated energy production gas stream containing methane involves adding an aqueous nitrate solution to the hydrogen sulfide-contaminated energy production gas stream in aqueous biofilter system, contacting the hydrogen sulfide-contaminated energy production gas stream with microorganisms of humidified biofilm, oxidizing a portion(s) of hydrogen sulfide in the hydrogen sulfide-contaminated energy production gas stream using microorganisms under anoxic conditions to produce hydrogen sulfide-depleted energy production gas stream. The aqueous biofilter system comprises biofilter (6) having biofilter support material containing a biofilter bed supporting a humidified biofilm including microorganisms which are capable of oxidizing hydrogen sulfide. An INDEPENDENT CLAIM is included for aqueous biofilter system.    DESCRIPTION OF DRAWING(S) - The drawing shows schematic view of aqueous biofilter system.    Hydrogen sulfide-contaminated energy production gas stream (1)    Biofilter (6)    Gas pump (7)    Injector (8)    Aqueous biofilter system (10)