The Sacramento Metropolitan Utility District (SMUD), in conjunction with the Sacramento Regional Wastewater Treatment Plant (SRWTP), is planning to construct and operate a cogeneration plant fueled by natural gas and the SRWTP’s digester gas. Once the cogeneration plant comes on line, SMUD will purchase about 90 percent of the digester gas produced by the SRWTP. The remaining digester gas will be burned in the waste gas burners. The Sacramento Metropolitan Air Quality Management District (SMAQMD) requires that all digester gas sent to new or modified combustion devices be treated to reduce hydrogen sulfide (H2S) concentrations. This reduction in digester gas H2S concentrations will result in lower sulfur oxide (SOx) emissions in the combustion exhaust. This requirement applies to all digester gas being sent to the new SMUD cogeneration plant and the new SRWTP waste gas burners. Typically, to control SOx emissions from digester gas combustion equipment, the H2S concentration of the digester gas is reduced prior to combustion.