Abstract
Influent load of oil (hexan-extractable materials) and mechanism of it's removal in municipal sewage treatment plants recieving domestic wastewater mainly were investigated.
Oil discharge per capita from household was about 7g/d, and was considered to be derived from fecal materials and housework (vegetable and animal oil). In combined sewerage systems, however, it was found that larger amounts of oil which had been settled in sewers were washed out by rainstorm.
Oil removal was performed more than 95% in conventional activated sludge process, and the following two stages were attributed; (1) Sedimentation of settleable oil in primary settling tank, (2) Rapid adsorption and relatively slow biochemical decomposition by activated sludge, and sedimentation in final settling tank.
