| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To realize further an improvement in treatment efficiency and amount reduction of generated surplus sludge while maintaining stable treated water quality in a single tank type activated sludge method or a multistage activated sludge method using the predatory action of animalcules. <P>SOLUTION: In biological treatment where organic wastewater is introduced into a first biological treatment tank 1A to be biologically treated by bacteria, the treated liquid containing the bacteria from the first biological treatment tank 1A is introduced into a second biological treatment tank 1B to be treated with activated sludge, and the treated liquid from the second biological treatment tank 1B is solid-liquid separated into the sludge and treated water, a part of the sludge in the second biological treatment tank 1B and/or a part of the separated sludge are introduced into a sludge treatment tank 3, in which an immersed membrane 4 having a pore size of 5-100μm is installed, to be subjected to aerobic treatment, and the permeate of the immersed membrane 4 is returned to the first biological treatment tank 1A and/or the second biological treatment tank 1B. The amount of the sludge is reduced by the animalcules in the sludge treatment tank 3, and uneaten fine components are permeated through the immersed membrane 4, and then returned to the filter predatory animalcule tank 1B again to be preyed, which enables obtaining of both high sludge amount-reducing effect and excellent treated water quality. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
