Design Of Automatic Control System Of Wastewater Treatment Plant

As the characters of wastewater treatment process is nonlinear and multivariable, traditional control strategies in wastewater treatment plant have used traditional meters and manual control model. Moreover the whole control process has been dependent on people's knowledge and experiences, which means unstable water's quality, low labor productivity and decentralized system information. Fully automatic control wastewater treatment plants are decisive in order to improve the quality of water treatment and reduce the cost of manufacturing. This can only be done by applying advanced automatic control equipment and technology.This paper introduces the automatic control system of LongQuan Water Work. The improved oxidation ditch is adapted in the process of treating wastewater and water sludge. The structure of automatic control system, has complete function, flexible form, high ratio of performance to price and friendly interface. It is composed of PLC, Switches and IPC. Intended for the characteristic of complexity, multi-variable, multi-loops, big time-delay and nonlinear during the process of wastewater treatment, a Fuzzy PID controller is used in chlorine feeding, chemical dosing and aeration basin DO controlling workshop, in which the PID parameters are adjusted by a fuzzy algorithm. Test results show that the controller works stably and enduringly, and good controlling quality is obtained with a low cost. The IPC of this automatic control system is realized with Intouch 8.0 based on Windows 2000, and the PLC of Schneider Co. ltd. is designed by trapezoid graphic software.The technological process of wastewater treatment, as well as the hardware and software is discussed in this paper. We have also completed the debugging of all the equipment. The automatic control system has been put into field operation successfully for one year. The running result shows that the treated water's quality is up to State Standards for safe sewage discharge. Even a high quality and a stable performance can be achieved in this control system. This paper reaches the requirements of the design and can be a good example for automatic control system design in similar cases. Conclusively this paper also gives some thought to future development and implementation of automatic systems in the waste water field.