DEVICE FOR CONTROLLING FLOW RATE OF RETURN WASTE WATER IN WATER PURIFYING PLANT

摘要

PURPOSE:To obtain an appropriate quality of treated water by considering a flow rate pattern of waste water flowing into a waste water pond and the capacity of the waste water pond, and calculating a schedule of desired values of return waste water desirable for returning systematically waste water. CONSTITUTION:The waste washing water of a filter basin 4 or the treated water freed of sludge from a sedimentation pond 3 is collected in a waste water pond 8, and returned to a cistern 2. The flow rate of the return water is controlled in accordance with the amt. of said waste water and the water level of the waste water pond. In said return water flow rate controllers 19 and 20 of a water purifying plant, an arithmetic logic for estimating an influent flow rate pattern of the waste water pond in a day from the influent flow rate of the waste water pond, the water level of the waste water pond, and the washing cycle or the sludge discharge cycle, an arithmetic logic to calculate a planned schedule of return waste water flow rate for minimizing the variation in the return flow rate on the basis of said estimated influent flow rate pattern, and an arithmetic logic for calculating a desired pattern of the smoothed return waste water flow rate while controlling said planned schedule of return waste water flow rate and the water level of the waste water pond within specified limits are provided.