Study On Automatic Control System Of Yunnan Mine Wastewater Treatment

As the sewage treatment is a control process of complex and multivariable, the main control mode in traditional wastewater treatment plants is manual control. However this control method which is dependent on the human’s experience will lead to unstable water quality, lower productivity and energy efficiency. In order to In order to ensure the quality of water treatment and reduce the production cost of wastewater treatment, the advanced automatic control system must be used to control the sewage treatment.A automatic control system of sewage treatment has been designed based on sewage treatment station of living area in mine which is in Yunnan. it is used of chemical precipitation method and advanced CASS technology in the sewage treatment station. The control system of sewage treatment which is a Distributed Control System is made up of industrial computer (IPC) and programmable logic controller (PLC). Many advantages is brought by this control system, such as complete structure function, flexible configuration, good expansibility. In order to ensure the stability of water quality, PID control algorithm is used in the control link of pH and underflow concentration of thickener. Monitoring software of upper computer in the control system is designed by WinCC7.0.Lower machines are consist of SIEMENS PLC S7-300, The control program of the lower computer PLC is designed with the ladder diagram of SIEMENS STEP7.At the beginning of the article, On the basis of the analysis and discussion for the process method of wastewater treatment, the process flow of sewage treatment for living quarters in mine is developed. Then, it is The PLC S7-300 and the programming software STEP7 that is introduced in detail. After that, the control system is designed by the following work, such as Formulating overall control scheme, designing the structure of the system and the hardware configuration, writing control programs and designing the upper monitoring software. Control system will be debugged after the system being built. Then, the system will put into practice. After the control system running, the effluent’s quality reaches the national standard,. Control system is stable, and the design requirements are met. In the end, the paper puts forward some prospects for the development of the automatic control system of wastewater treatment.