Dual blower arrangement used for a sewage treatment plant. The blowers inject air into a distribution manifold, providing aeration to the full volume of the bioreactor.
Because air is compressible, the air temperature at the blowers is significantly higher than ambient. The deeper the bioreactor, the higher the manifold temperature at the blower. For that reason, stainless steel is preferred as a manifold construction material.
For efficient sewage treatment, biomass needs dissolved oxygen. Transfer efficiency of oxygen from air is a function of
- water depth
- water temperature
- atmospheric pressure (which is determined by height above sea-level)
- oxygen concentration in air (21%)
- diffuser characteristics
- manifold characteristics
Heterotrophic bacteria need dissolved oxygen to degrade organic material and nitrifying bacteria need dissolved oxygen to convert ammonia to nitrate.