Domestic sewage treatment - in two biological stages with self-induced sludge recycling

摘要

A domestic sewage treatment plant consists of a pre-clarification tank and two biological stages, each consisting of an aeration section and a reclarification section. The turbulence produced by aeration is utilised to convey activated sludge against the general flow direction from the second stage back to the first stage. This saves the necessity for any recycling pumps and the power consumption for their drive. The reflux taxes place during periods of little main flow. The risk of sludge being washed out by impact loads is greatly reduced.