TREATMENT OF SEWAGE BY ACTIVATED SLUDGE

摘要

PURPOSE:To sufficiently exhibit a function even when load fluctuation is made large by regulating the drawing amount of sludge from a reaction tank so that SRT correspondent to the inflow pollutant load is obtained and also regulating the practical ratio of an aerobic treatment time to an anaerobic treatment time in accordance with the inflow pollutant load and controlling ASRT to constant. CONSTITUTION:The drawing amount of sludge due to a pump P1 is regulated so that SRT reversely proportioned to the inflow pollutant load introduced into a reaction tank 1 is obtained in accordance with this inflow pollutant load. In other words, the drawing amount of sludge is increased and decreased in accordance with increase and decrease of the inflow pollutant load. Further the ratio of an aerobic treatment time to an anaerobic treatment time is regulated according to the inflow pollutant load introduced into the reaction tank 1. This is executed by regulating any one or both of an aeration time wherein air is fed into the reaction tank and an aeration stopping time. Thereby since ASRT is controlled to constant, the load of nitrifying bacteria is properly held and activity is not deteriorated and treatment is excellently performed even when load fluctuation is made large.