BIOLOGICAL TREATMENT APPARATUS, BIOLOGICAL TREATMENT METHOD, AND PROGRAM

To provide a method in which the flow rate of the permeated water is ensured stably even when fouling has progressed.SOLUTION: A biological treatment apparatus 100 comprises: a biological treatment tank 11; a membrane separation device 1 having a tubular filtration membrane with a monolayer structure copolymerized with a hydrophilic monomer; a booster pump 21 for supplying feed water W3 to the membrane separation device 1; a suction pump 22 for sucking permeable water PW from the membrane separation device 1; a back pressure regulating device 23 for regulating a back pressure in a permeation side space; an inter-membrane differential pressure measuring device 14 for measuring a pressure difference between the membranes; and a control device 13 for controlling the booster pump 21, the suction pump 22, and the back pressure regulating device 23. The control device 13 comprises: a back pressure regulating part 13a for decreasing the back pressure when the inter-membrane differential pressure has increased to a predetermined value or more; and a setting changing part 13b for controlling one of the booster pump and the suction pump when the back pressure regulating device has reached a regulation range limit, so as to increase one of a boosting pressure of the booster pump and a suction pressure of the suction pump, as well as to increase the back pressure.SELECTED DRAWING: Figure 1 【課題】ファウリングが進行した場合においても、安定して透過水の流量を確保する。【解決手段】生物処理水槽１１と、親水性モノマーが共重合された単層構造を有する管状濾過膜を有する膜分離装置１と、膜分離装置１に供給水Ｗ３を供給する加圧ポンプ２１と、膜分離装置１から透過水ＰＷを吸引する吸引ポンプ２２と、透過側空間の背圧を調整する背圧調整装置２３と、膜間差圧を計測する膜間差圧計測装置１４と、膜間差圧に基づき加圧ポンプ２１、吸引ポンプ２２、及び背圧調整装置１４を制御する制御装置１３と、を有し、制御装置１３は、膜間差圧が所定値以上に増加した場合、背圧を減少させる背圧調整部１３ａと、背圧調整装置の調整範囲の限界に達した場合、加圧ポンプと吸引ポンプとの一方を制御して、加圧ポンプの加圧力と吸引ポンプの吸引力との一方を増加させるとともに背圧を増加させる設定変更部１３ｂと、を有する生物処理装置１００を提供する。【選択図】図１