| 摘要 |
PURPOSE:To treat org. waste water biologically, prevent the clogging of a separation membrane and clean the surface of the membrane properly without destroying sludge floc by providing an ultrasonic generator for imparting an ultrasonic vibration to a mixed liq. stored in a denitrification tank. CONSTITUTION:A waste water 2 is mixed with activated sludge in a denitrification tank 1 to form a mixed liq. 5, which is then subjected to oxidative decomposition by the respiration of denitrification bacteria cultivated in the activated sludge. The mixed liq. 5 is given an ultrasonic vibration and, by the resulting flocculating action, the fat and oil 23 having a relatively small size in diameter are collected into the masses of a larger diameter, which are then floated for separation and, the fine air bubbles 24 formed by the foaming action resulting from the aforesaid vibration adsorb the fat and oil 23 in the mixed liq. 5 to accelerate the floatation separation thereof. The mixed liq. 5 is then passed through a membrane separation device 9 to remove the solid from the liq. which has passed through a separation membrane 11 is extracted as a purified water 22 and the activated sludge, together with a circulating nitrification liq. 19, is sent back into the denitrification tank 1. |
