Control System Design Of CASS Sewage Treatment Based On Fuzzy Control

Water resource is the foundation of human life and production, but there is an increasingly cost for the sewage from life and industry with its rising volume as the development of urbanization and industrialization. Waste water processing system is the base of modern city as well as its key roles in countering water contamination and improving water quality. Therefore, the relevant waste water processing technique turns into the key to the system.Based on the analysis of current research and problems of automatic control systems for sewage treatment from home and aboard, this paper introduces a sewage treatment plant in Yibin which the CASS sewage treatment technological principle and process are in application. And combined with the sewage treatment system with nonlinear, time variability and complexity characteristics, proposes the application of fuzzy control strategy in CASS sewage treatment aeration process, selects the dissolved oxygen (DO) as the controlled variable in the CASS biochemical pool aeration process. The MATLAB simulation shows that the system has satisfied control effect, and problems of nonlinear, large inertia and so on are preliminarily solved. At the same time, combined with the fuzzy control principle and PLC automatic control technology, a aeration control system has been designed on the basis of fuzzy control principle and PLC application for CASS sewage treatment process. This paper has achieved the PLC model selection of CASS biochemical pool aeration in relevant part and the hardware design of corresponding control cabinets I/O distribution in electrical part. The fuzzy control strategy proposed above is used in actual concentration control of CASS biochemical pool dissolved oxygen (DO), the fuzzy control algorithm in the Siemens S7-300 programming, so the relevant program design of the system has been accomplished. Finally, according to the control requirements, using the WinCC configuration software to design host computer monitoring interface, the visual monitoring and adjustment function of the equipment’ running state, real-time data acquisition and alarm function have been realized.By applying the fuzzy control theory in PLC to achieve the control of the blower as the operating unit and to achieve the control of dissolved oxygen (DO) in the treatment of CASS process. Through the debugging and running, the system is in good working condition, and all the indexes meet the designed operation requirements. Its application significantly improve the efficiency of sewage treatment and water quality of sewage treatment, enhance the operation and management level, so as to save the cost of sewage treatment and improve the efficiency of sewage treatment.