Development Of Micro Power System For Sewage Treatment

With the continuous development of economy and society, water pollution is becoming more and more serious. The sewage treatment in rural areas and some communities which are not connected to sewage network has been in a backward level, and this sewage discharge has become one of the main sources of the river pollution. In view of the sewage problem of the rural area or not access to urban sewage network, this project developed a small-power, low-energy micro power system for sewage treatment. The sewage treatment system adopts the activated sludge process,a kind of biological sewage treatment method,which removes the pollutant through the microorganism metabolism without adding chemicals,and the quality of effluent water meet the emission requirements. In order to meet the requirements of automatic operation, this paper developed a sewage treatment control system based on PLC.The sewage treatment process of this project is AA/O(Anaerobic-Anoxic-Oxic,AA/O) process.Through three steps of anaerobic, anoxic and aerobic treatment,this process can not only remove organic pollutants in wastewater,but also removes nitrogen and phosphorus.According to the quality, quantity and emission requirement of sewage water, the structure size of each reaction tank and the aeration amount of aeration tank are designed and calculated. According to the requirements of sewage treatment process, design the overall control scheme, hardware selection and circuit, and then write the PLC program to meet the specific requirements of the control system.This sewage treat control system has functions such as the manual processing, automatic processing and alarm inquiry,and can set and display the parameter through the touch screen.Dissolved oxygen is an important parameter in the process of sewage treatment,so the control of dissolved oxygen is a very important link in the process of sewage treatment.Due to the difficulty of establishing mathematical model of dissolved oxygen in sewage,control the amount of dissolved oxygen through the PID control method, which can keep the dissolved oxygen in aerobic pool at a stable level.