| abstract |
A method for treating organic wastewater is provided. For an organic wastewater treatment device, the inflow of organic wastewater, the liquid level of the water tank, the pressure difference between the membranes of each membrane separation device, the T-N of the treated water, and the NH3 -N concentration of the treated water are calculated. At least one of these is used as an index, and it is determined whether or not the membrane separation device in operation is stopped or whether the membrane separation device is being stopped, for each of the biological treatment units, thereby efficiently performing biological treatment. The organic wastewater treatment device includes a biological treatment tank, an oxygen-deficient tank disposed on the upstream side along the flow of the nitrogen-containing organic wastewater, and a membrane separation device disposed on the downstream side and immersed in the activated sludge. The aerobic tank is used as a pair of biological treatment units, and a plurality of biological treatment units are connected in series; and the sludge return path returns activated sludge from the aerobic tank arranged at the most downstream to the anoxic tank arranged at the most upstream. |