Biological waste water purification process and device

摘要

Biological wastewater is purified in a sewage treatment plant having an activation tank of a depth greater than approximately 5 m per meter into which a feed of compressed air is fed. An oxygen-containing gas having an oxygen content is increased with respect to the air or pure oxygen and is fed to the mixed liquor in at least a part of the aerobic tank volume of the activation tank. The oxygen containing gas is fed until the total content of the gas in the mixed liquor based upon saturation value is below 150% before the mixed liquor is fed to a secondary clarification.