- Sulfur is used in every cell as a micronutrient.
- Sulfate is used as an alternative electron acceptor by certain species of bacteria (ex. Desulvibrio sp.) under reducing environment which produces sulfides an H2S (pH dependent as to which forms are present).
- Sulfate reducing microbe populations are significant when dissolved oxygen is depleted, there are simple organics and the waste stream contains sulfate. We know sulfate reducing bacteria are favored under low redox < -150 mV @ pH 7.0.
- Nitrate, if present, yield more energy if used as an electron acceptor (different bacteria) which means that by adding nitrate we can have faster growing cultures degrade available organics preventing the formation of reduced sulfur (S=, H2S).
- Reduced Sulfur is converted back to sulfur and sulfate by microbial action.