| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus for treating organic sewage, whose energy consumption can be lowered drastically, in which the amount of waste sludge to be produced can be reduced drastically and with which easily treatable waste sludge can be obtained and to provide a method for treating organic sewage. SOLUTION: This apparatus is constituted of an anaerobic digesting tank 2, an aerobic reaction tank 3 into which the water 12 treated in the tank 2 is introduced, a precipitating tank 4 into which the water 13 treated in the tank 3 is introduced and in which the sludge produced by the aerobic reaction is precipitated and separated, a returning means 4b for introducing a part of the precipitated sludge obtained in the tank 4 into the tank 2 or a pretreatment tank 1 and another returning means 4a for introducing a part of the precipitated sludge obtained in the tank 4 into the tank 3. A contact filter medium is arranged in a multistage in the tank 2 so that one filter medium is not brought into contact with another filter medium, a bridge of sludge is not formed across the filter media and sludge is not hindered from precipitating floating. The pretreated organic sewage 11 is introduced into the tank 2 from the bottom and the anaerobically digested sewage is discharged from the top of the tank 2. A metering means is arranged in the tank 2 for controlling the amount of the sludge to be accumulated in the tank 2.
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