CONTROL METHOD FOR BATCH TYPE ACTIVE SLUDGE PROCESS

PURPOSE:To simultaneously remove nitrogen and phosphorus stably at a high rate by a method in which an OPR meter is installed in a reaction vessel, and denitrification, measurement of phosphorus releasing time, and determination of aeration time can be done accurately by detecting the appearance time of the inflection point on an OPR curve in an agitation process. CONSTITUTION:In a batch type active sludge process in which a treatment process cycle consisting of a combination of agitation and aeration, precipitation of active sludge, and discharge of treated water is repeated in a single reaction vessel to which drainage is fed to be treated, an OPR meter 10 is installed in the reaction vessel 2, and its output is inputted in a controller 9. The inflection point on an OPR curve in the agitation-aeration combined process is detected, and the appearance time of the inflection point is measured. The aeration time in the agitation-aeration combined process of the next cycle is determined on the basis of the appearance time of the inflection point in the cycle up to the present. By determining both agitation time and aeration time in response to the changes in the quality of raw water and operation conditions, simultaneous removal of nitrogen and phosphorus can be conducted stably a high rate.