The Design And Implement Of Multi-Mode A2/O Process Control System In Sewage Treatment

Water pollution causes water unqualified, water shortage causes inadequate quantity of water, water pollution and water shortage causes water crisis. But the basic countermeasure to solve the water problem is cyclic utilization, and the key is the sewage treatment. But in order to guarantee the sustainable development of the economy, sewage treatment has become urban development and construction indispensable facilities.In this paper, an automatic control system is designed based on a large sewage treatment plant in Shanghai, which adopts the improved sewage treatment process using multi-mode A2/O process (Anaerobic-Anoxic-Oxic process). The use of normal A2/O, reversed A2/O, phosphorus removal models, while removal of organic matter can achieve efficient nitrogen and phosphorus removal. Control system uses a three-tier network architecture. The whole control platform integrates early GE, Siemens PLC and new built AB PLC. The platform is fully functional, configuration flexibility, friendly interface, good compatibility, suitable for expansion, and mature technology, cost-effective. In this automatic control system, the program of upper computer is realized with RSView and industrial real-time database based on windows, and lower computer PLC is designed by trapezoid graphic software RsLogix5000 in order to achieve seamless integration of the whole system.Because of Complex process of the sewage treatment system, generally dissolved oxygen control by manual adjustment method, this method can't adapt to change of water quality and quantity, to ensure the effluent standard, often excessive aeration, so that increased energy consumption. The control system use Biotechnology Intelligent Optimization System (BIOS) and PLC intelligent control system. The system can control algorithm of biochemical pool dissolved oxygen DO and internal reflux ratio IRQ, ensure water quality and energy saving effect 20～40%.