FIXED BED TYPE WASTE WATER TREATMENT APPARATUS

PURPOSE:To prevent the killing of methane producing bacteria in a waste water treatment apparatus wherein an anaerobic biomembrane method is combined with an aerobic biomembrane method by detecting and controlling the cumulated inflow amount of inflow waste water and directly sending a part of waste water from a raw water tank to an aerobic bioreactor when the cumulated inflow amount of inflow waste water becomes much. CONSTITUTION:When the inflow of rainwater is detected by a control unit 13, the function of a main pump A3 is not changed hut a main pump B4 is stopped while a preparatory pump 5 is started. By this method, rainwater- containing sewage 1 exceeding a level M is directly sent to a an aerobic bioreactor 10. In this case, since the inflow amount of sewage 1 is reduced to a large extent in an anaerobic bioreactor 8, a stagnation time becomes long and the dissolved oxygen in the sewage 1 caused by rainwater is rapidly consumed by faculative anaerobes in the vicinity of the inlet of an anaerobic fixed bed 7 and, therefore, the adverse effect on methane producing bacteria is reduced and usual anaerobic treatment is kept.