| abstract |
Provided is a method for eliminating the decrease in the activity of the activated sludge treatment microorganism group, further improving the treatment capacity to increase the treatment efficiency, and reducing the amount of excess sludge. In the wastewater treatment method of the present invention, when the raw water (1a) is treated with activated sludge, the first sludge return step (Va) (in the first surplus sludge tank with aeration / stirring or sludge storage tank (12a), Returning the stirred sludge to the treatment tank, batch tank or anaerobic tank; and / or the second excess sludge tank with aeration / stirring or the concentrated sludge storage tank (13a), The step of returning to the treatment tank, batch tank or anaerobic tank) and the number of Bacillus bacteria in the treatment tank, batch tank or anaerobic tank to which the sludge has been returned is 2.0 × 10 5 to The activated sludge treatment is characterized by maintaining 22.5 × 10 5 cfu / mL. |