| 摘要 |
PURPOSE:To perform efficient treatment by keeping the activity of a microorganism optimum, by guiding the outflow or inflow solution of a biological treatment tank to a cooling vessel to cool the same under reduced pressure before flowing the cooled solution to the biological treatment tank. CONSTITUTION:A part of the solution mixture or treated water, which contains nitrite nitrogen and nitrate nitrogen formed by nitration, in a nitration tank 12 is recycled and returned to a first denitrafication tank 11 as a recycle solution R but, at this time, a part or all of the recycle solution R is allowed to pass through a cooling vessel 21 to be cooled under reduced pressure. Thereafter, the cooled recycle solution R is returned to the first denitrification tank 11 by a pump 22. By this method, org. waste water is treated efficiently in a non-dilution or a low dilution state to obtain treated water having good quality. |
