SEWAGE PURIFYING APPARATUS

PURPOSE:To perform long-term operation maintaining high purifying capacity, by a method wherein the separation chamber of a centrifugal separator is reduced in pressure by a pressure reducing operation means through a vacuum tank to introduce sewage and, after the sewage is subjected to centrifugal separation, the clarified liquid obtained is led out to be capable of being supplied to a user side. CONSTITUTION:A vacuum pump 45 as a pressure reducing operation means B is operated to reduce the pressure in a vacuum tank 39 and the separation chamber 10 of a centrifugal separator A is reduced in pressure to inject the sewage such as cutting oil in a sewage tank 35 into the separation chamber 10. Gases in the sewage are removed by pressure reducing action at this time and a kind of reducing treatment is performed to develop deodorizing effect. Next, sludge is centrifugally separated from the sewage by operating the centrifugal separator 10 and charged in a sludge batch 53. The liquid after separation is introduced into the vacuum tank 39 to again receive reducing treatment and led out to a purified liquid tank 41 and subsequently supplied to a user by driving a compressor 47 and a pump 43.