A fuzzy logic based coagulant real time control scheme for water purification system

Water purification process involves many complex physical and chemical phenomena, and thus it is difficult to realize optimum coagulant dosing control with traditional methods. In this paper, the feasibility of applying a fuzzy logic inference to determine optimum chemical dosage and to control the performance of coagulation process was discussed. Prior to field test, a fuzzy logic based control scheme, which can realize the optimum coagulant dosing rate control according to the variety of raw water characteristic, was designed and applied to a middle-scale water treatment process. An online self-adjustment of coagulant dosing set point based on fuzzy logic inference algorithm was proposed and programmed by SIEMENS SIMATIC200 PLC. Field test indicated that the proposal control scheme is validated and has considerable practical value.