Last month we discussed how, in gravity systems, effluent distribution over the area of a sewage treatment trench is accomplished by the biomat. Full treatment efficiency is not obtained until the biomat has developed over the infiltrative surface of the trench; the entire area is used throughout the day. If pressure distribution is used to deliver effluent to the trench or bed, effluent is spread across the entire system area from Day 1 of system operation.
Pressure distribution involves the use of a pump to pressurize the distribution network and ensure equal amounts of effluent are delivered throughout the network. The
