Research On Automatic Control System Of Tannery Wastewater Treatment Based On PLC

China is a country short of water,even in the south of the China.The rapid development of industry has aggravated the pollution of water.In recent years,China's economy has developed rapidly,and the market demand for leather continues has improved,leather industry has improved,but a large amount of tannery wastewater has polluted the environment.So it is useful to study tannery wastewater treatment process according to the characteristics of tannery wastewater.With the development of computer technology and modern control technology,the automatic control system based on PLC technology has also been developed.So the research of tannery wastewater treatment automation system based on PLC has far-reaching practical significance.This passage starts from the study of tannery process,then study the characteristics of tannery wastewater in tannery process and the treatment process of tannery wastewater.This article put forward a treatment process of tannery wastewater with chromium-containing wastewater pretreated and combined wastewater treated by oxidation ditch process.On this basis,this paper designs an automatic control system based on PLC.The basic structure of the system is that Siemens PLC is used as the controller of the lower computer.The operation panel,PH sensor,dissolved oxygen sensor and liquid level sensor are input or collected.The pump,agitator,grille and aerator of each subsystem of the wastewater treatment system are PLC.The control equipment of the output terminal takes the touch screen as the front-end information processing equipment of the whole equipment and the force control configuration software as the configuration software of the upper computer to control the whole system at the management level.In this paper,the design of hardware system adopts SIEMENS company's S7-200 PLC,MCGS touch screen and industrial control machine control grille,submersible mixer,aerator and other common sewage treatment equipment.In the software,STEP 7-Micro/WIN programming software is used to program SIEMENS company's S7-200 PLC,configuration software of MCGS for touch screenengineering programming,forcecontrol v7.1 to configure remote monitoring system.Communication is carried out using the Modbus protocol to realize real-time data transmission and device communication of the automatic control system.The automatic treatment of tannery wastewater through automatic control system is of positive significance for environmental protection,accelerating industrial upgrading and promoting the sound and rapid development of local economy.The whole system is suitable for small tannery wastewater treatment station,which can serve local economic development better.