The presence of sulfate in wastewater can reduce the amount of methane that can be produced from the degradation of wastewater organics. Sulfate reducing bacteria (SRB) use various electron donors partially and completely oxidizing them while reducing SO 4 2 − https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351076036/3c3ba884-0006-417c-87bb-dfd7ee57a6e6/content/inequ51_1.tif"/> to H2S. It is well documented that both sulfate reduction and methane production can occur in the same environment. It is also well documented that SRB may outcompete the consortium of bacteria responsible for methane production. Several explanations for the reported predominance of SRB include energetic advantages, kinetic advantages, and toxicity. There is considerable interest in preventing sulfate reduction to H2S from occuring. One possibility to add molybdenum (Mo) since some literature reports indicate that Mo is toxic to SRB at lower concentrations than those reported to be toxic to methane-producing organisms. 1 - 3