| 摘要 |
PURPOSE:To obtain activated sludge of low BOD and COD by concentrating the waste water from a biological treatment system by making use of a special permeable membrane, return this to said biological treatment system, and enable the waste water to be released by again concentrating and decomposing the high BOD and COD in the permeated liquid. CONSTITUTION:The waste water 1 of a high concn. is treated in a biological reacting vessel A and is introduced into a microporous membrane or ultrafiltration membrane mounting cell B. The greater part of the activated sludge 4 concentrated in the mounting cell B is returned to the reaction vessel A. On the other hand, the membrane permeated liquid 5 from the mounting cell B goes to an electrolyzing device C where it is subjected to electrolysis, after which it is sent to an ultrafiltration membrane or reverse osmosis membrane mounting cell F where it is treated. It is equally well to carry out permeable membrane treatment in place of the above- mentioned electrolytic treatment. In this way, the return of the activated sludge of less COD and BOD components is accomplished, and the biological treatment reaction is accelerated. It is also possible to obtain low COD and BOD. |
