FLOCCULANT INJECTION CONTROL DEVICE

PURPOSE:To maintain turbidity of distributed water below a fixed level and at the same time, reduce a flocculant injection amount by adding a correction value in consideration for making the quality of treated water uniform through mixing, against a flocculant injection rate obtained based on the turbidity level of water. CONSTITUTION:In a purification plant which performs water purification by injection of a flocculant into water, the injection of a flocculant is controlled by addition of correction values to a flocculant injection rate obtained based on the turbidity of water. This aims at the maximization of elimination rate of turbidity with a consideration for making uniform the quality of treated water through mixing in a long resident time of the water in a sedimentation and a distribution pond. Consequently, the turbidity is uniformly mixed, even if water having a little higher turbidity level which is generated by reduction of a flocculant injection amount is allowed to flow in the water of low turbidity level existing in the sedimentation and distribution pond. Thus the turbidity level of distributed water can be maintained below the reference value.