Based on existing information concerning the effects of pressure on the biodegradability of sanitary sewage, a model activated sludge reactor was used in conjunction with pressurization to determine the viability of pressurization as a primary sewage treatment process.

Municipal sewage samples were pressurized at 40 psig for one hour with an excess of oxygen. An air compressor and a steel drum were used for sample pressurization. A non-pressurized control sample was maintained. After pressurization, the samples were fed into separate model activated sludge reactors. Biodegradability of both types of effluent was measured by determining their five day biochemical oxygen demands (B.O.D.).

Other tests were performed on the samples to measure turbidity, ammonia content, and long term B.O.D.

It was found that after treatment in the reactor, no definitive measured effect due to pressurization was observed in the five day B.O.D. test. However, the pressurized effluent was found to be more turbid, and to have a higher ammonia content than the non-pressurized sample. The long term B.O.D. tests indicated some divergence between the pressurized and non-pressurized effluent B.O.D. curves.