OPERATING SYSTEM FOR SEWAGE TREATMENT SYSTEM BY ACTIVATED SLUDGE METHOD

摘要

PURPOSE:To operate a sewage treatment system efficiently by determining the flow rates of return sludge and excess sludge at which an aeration tank is operated at the smallest possible deviation values of MLSS concn. and return sludge from target values and operating said tank. CONSTITUTION:Manipulated variables are the three flow rates; the flow rate of withdrawal from settling basin, the flow rate of return sludge and the flow rate of excess sludge. If the flow rate of withdrawal from settling basin and the flow rate of return sludge out of these tree flow rates are determined, the remaining one flow rate is determined. The flow rates are controlled by means of pumps 5, 7, and control valves 8, 9. To determine the flow rates, the sludge concns. of the respective parts are calculated, for which the mathematical models of an aeration tank 2 and a final settling basin 3 are used. Algorithm is constituted of the aeration tank model which calculates the MLSS concn. on the outlet side of the tank 2, and the settling basin model which calculates the MLSS concn. on the outlet side of the aeration tank, the flow rate of sewage and the flow rate of the sludge withdrawn from the settling basin.