Design Of Automatic Control System Based On PLC In Sewage Treatment Process

Water is the basis of human living. With the rapid development of the nationalurbanization, industrialization, a lot of life and industrial wastewater discharge,leading to the sharp decline of water quality of our country’s existing water resources.water pollution is becoming increasingly serious. With the continuous development ofour country’s economy, wastewater treatment have been playing an important role inour urban construction. Recently, with morefocus and demandson water protectingincreasing and automation of wastewater treatment promoting, most of advancedcontrol technologies anddevices are used in the sewage treatment. For the purpose ofimproving the efficiency of wastewater treatment and increasing economic benefits,designing a set of effective monitoring system is necessary.With the platform of Alien-Bradley PLC of Honeywell International Inc, thethesis introduce the achievement of PLC in sewage treatment process by a existedengineering case. This case used PLC as controller, combing various onlineinstruments to complete the detection of the effluent quality (such as: PH value, CODvalue) and according to the sewage treatment characteristicsand requirementshavecompleted the control of field devices; through monitoring system, the staff cansupervise and control the wastewater treatment in remote mode, at the same timethesystem is also designed reporting features for the late analysis. Generally, large timedelay, nonlinear and strong interference are existed in sewage treatment system, it isdifficult to establish an accurate model of the sewage treatment process control. Byanalyzing the mechanism of the sewage treatment process, this case design a entireDCS and communication network of sewage treatment control system according to theprocesses of actual application in daily production and make a detailed descriptionabout control program in main process of sewage treatment process.This design of sewage treatment and automatic control system can realize entirecontrol of sewage treatment through the management layer of the central controlsystem and the operation layer of PLC control stations, finish all the jobs ofmonitoring and scheduling management of sewage treatment process; and in aspectsof control effects,accuracy, conveniences, compatibility are all achieved and make aexpected goal. So, this passage are significant about sewage treatment control system.