| 摘要 |
PURPOSE:To treat org. sewage under a good control condition at low cost, by flocculating a slurry subjected to biological nitration and denitrification treatment after centrifugal separation to subject the same to membrane separation or by directly flocculating the same to perform membrane separation and returning a part of the centrifugally separated sludge and the membrane separation slurry. CONSTITUTION:In the treatment of org. sewage such as excretion or sewage, raw water is introduced into a biological nitration and denitrification treatment tank 2 at first to remove BOD and nitrogen. Next, this activated sludge slurry is separated into a solid and a liquid by an centrifugal separator 4 and water is sent to a membrane separator 9 from a centrifugally separated water tank 16 but an inorg. flocculant such as FeCl3 is added to said water to flocculate colloidal particles and COD. The greater part of the centrifugally separated sludge is recycled to the tank 2. When the centrifugal separator 4 is not used, the activated sludge slurry is directly guided to the tank 6 and an inorg flocculant is added to perform membrane separation and the membrane separation slurry is returned to the tank 2. By this method, low cost treatment easy to control is performed. |
