| 摘要 |
PURPOSE: To prevent the deposition of oil on the surface of a separation membrane at the time of biologically treating an oil-contg. waste water by treating the waste water added with a saponin-contg. agent in a biological treating tank and then separating solid from liq. in a membrane separator. CONSTITUTION: A membrane separator 3 is set in an aeration tank 2 for aerating the waste water from a food factory added with a saponin-contg. agent to biologically treat the waste water, and the treated water separated therein from solid is sent to a treated water tank 4. Since a negative pressure is exerted on the inside of an ultrafilter membrane into which plural sets of two membranes are incorporated in the separator 3, the treated water is sucked from the outside. Meanwhile, an aerator 5 is arranged below the separator 3 to remove the deposit on the membrane surface by aeration. By this method, the oil in the waste water is easily digested and decomposed by the emulsifying action of saponin, hence the membrane permeating flux is not decreased due to the deposition of oil on the membrane surface, and solid and liq. stably separated in the membrane separator 3. |
