TREATMENT OF SANITARY SEWAGE IN BATCH TYPE SANITARY SEWAGE TREATING DEVICE

摘要

PURPOSE:To enhance treatment efficiency and simultaneously to reduce the load of a batch type activated sludge treating tank and to enhance nitrification efficiency by forcedly returning one part of supernatant produced in the batch type activated sludge treating tank to the inlet of an anaerobic filter bed tank being the treating tank of the preceding stage and diluting the concn. of organic substance in the anaerobic filter bed tank. CONSTITUTION:Sanitary sewage is supplied to the reference water surface of a batch type activated sludge treating tank 3 via a first tank 1 and a second tank 2 of an anaerobic filter bed tank. Then the water to be treated which is supplied from the second tank 2 is mixed in an oxygen-free state by a pump P2. This water to be treated is agitated by performing diffusion from a diffuser 5. While the same is uniformly mixed with activated sludge, treatment is performed for a specified time. Thereafter diffusion through the diffuser 5 is stopped and the water to be treated is made silent for at least 15 minutes and floating sludge is precipitated. Thereafter one part of supernatant is returned to the inlet part of the first tank 1 of the anaerobic filter bed tank. The other supernatant is filtered by a membrane filter 4 and discharged to the outside. This is repeated at four times while keeping it as one cycle.