| 摘要 |
PURPOSE:To obtain treated water having good quality, by applying methane fermentation treatment in a reaction tank and returning the concentrate of an ultrafilter to the methane fermentation tank to aerate the same. CONSTITUTION:Sewage is supplied to a reaction tank 1 to be subjected to methane fermentation treatment. The treated water from the reaction tank 1 is passed through an ultrafilter 2 while the concentrate is recirculated to the reaction tank 1 and subjected to aeration treatment for removing COD in an aeration tank 3 because the COD value of said treated water is high. A transport passage 7 with a pump P for sending treated water from the reaction tank 1 to the ultrafilter 2 and a return passage 6 for returning the concentrate from the ultrafilter 2 to the reaction tank 1 are provided between the reaction tank 1 and the ultrafilter 2 so as to connect both of them. By this method, the quality of treated water is kept well.
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