| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the lowering of removing effect for bacteria adhered to a separating membrane surface of a membrane separation device and lower ing of flux from occurring by feeding pressurized water in which oxygen is pressure dissolved into a fluidized biological treatment device. SOLUTION: A fluidized biological treatment device 2 is constituted of a biological reaction tank 6 and a pressurized water preparation device 10 for pressure dissolving the oxygen. Optional type pressurized water preparation devices 10 can be used as far as the pressurized water is brought into contact with oxygen containing gas or air in the devices. For instance, compressed air from an air compressor 11 is mixed with treated water from a tank 3 in an ejector 12 to prepare oxygen containing pressurized water, which is stored in a pressure tank 14. The oxygen containing pressurized water is fed into the bottom section of a biological reaction tank 6 by a feed pipe 16. A large amount of oxygen is replenished into the biological reaction tank 6 by the arrangement. Biological degradation, therefore, can be carried out sufficiently even when the organic matter concentration is high, and nitrification can be carried out perfectly, and even when NH4 <+> concentration is high, adhered bacteria can be removed completely and the lowering of flux can be prevented.</p> |
