BIOLOGICAL WASTEWATER TREATING SYSTEM

摘要

A modified activated sludge system is provided wherein wastewater containing BOD and phosphate values is admixed with biomass-containing recycled sludge under conditions effecting sorption of BOD in the biomass (A), then said wastewater is subected to aeration in an oxidation zone (B) under conditions effecting oxidation of BOD, including a dissolved oxygen level in said zone of less than one part per million. By such operation, considerable savings in power requirements for oxygen transfer to the mixed liquid are had, while developing and maintaining a dense non-bulking biomass having the properties of good removal of phosphate from the waste-water influent. By operating the system at high influent throughput rate (F/M), external oxygen requirement for BOD removal is minimized.