| 摘要 |
<p>PURPOSE:To efficiently denitrify crude night soil, by circulating the nitrified- denitrified liquid of crude night soil between a flotation tank and a pressure tank to perform nitrifying-denitrifying reaction, and returning a part of separated sludge in a separation tank to an aeration tank. CONSTITUTION:Crude night soil after being pretreated is introduced into an aeration tank 1, where aeration is performed for the removal of BOD and nitrification-denitrification. The liquid from the aeration tank 1 is sent to a flotation separation tank 2, where the flotation to let solid matter float up with gas bubbles formed by returning a pressurized liquid to ordinary pressure is performed. A part of the separated sludge is returned as turned sludge to the aeration tank 1, while the remainder is disposed as excess sludge. A part of a liquid having accepted the separation of sludge in the flotation tank 2 is sent as circulatory water to a pessure tank 3, while the remainder is withdrawn as treated water outside.</p> |
