SEWAGE TREATMENT METHOD BY BATCH TYPE ACTIVATED SLUDGE METHOD

摘要

PROBLEM TO BE SOLVED: To provide a sewage treatment method capable of automatic operation to cope with an abnormal state such as the increase in an MLSS concentration and bulking in consideration of the precipitation properties of sludge to solve the problem that, in a sewage treatment method by timer control automatic operation in a conventional batch type activated sludge method, when the precipitation of sludge is slow, activated sludge is discharged together with supernatant wastewater to deteriorate the quality of treated water so that maintenance by the experience and skill of an operator is necessary. SOLUTION: When agitating aeration is stopped, by a measured value obtained by the continuous measurement of a sludge sedimentation velocity by a sludge interface meter in a biological reaction tank, the length of supernatant drainage time and the length of excess sludge extraction time are set up, and the condition of treatment is determined from the sludge sedimentation velocity. When the treatment is normal, automatic operation is done. When the treatment is abnormal, and the MLSS concentration is increased, the automatic operation is continued while the amount of MLSS to be extracted is increased. When the treatment is abnormal, and the bulking is detected, the automatic operation is stopped, an alarm is outputted, and manual operation is done.