The Research And Application Of The Control Strategies In The Sewage Treatment Plant Control System

Aeration is an important part of biological sewage treatment, the concentration of dissolved oxygen (DO) is an important parameter to ensure that the sewage treatment is up to the standards. Studies have shown that controlling the dissolved oxygen concentration in a relatively stable concentration at a certain stage can effectively improve sewage treatment and effluent quality and save the amount of aeration. However, DO concentration fluctuations severely in many sewage treatment plants, and DO concentration changes lag behind the blower aeration rate. So it is not conducive to the stable operation of the sewage treatment system. In this paper, a controller is designed firstly to control the actual DO concentration stability at a set concentration.After review the extensive literature and analysis the actual sewage treatment plant operating situation,we obtained high DO set concentration may affect the biological pool anoxic denitrification,and the dissolved oxygen concentration is set to a different value can control the sewage treatment process better according to different in and out water quality. After in-depth study and experiment, this paper presents adjusting the set value of the concentration of dissolved oxygen dynamically according to the concentration of NH4-N at the outlet of biological pool and the export COD. NH4-N at the outlet of the biological pool can be measured easily online. And COD could draw more precise measurement values according to the instruments, but the line detector still have the problems of strong lagging behind,the large error and expensive. For example, it is generally tested once every4-12hours. So it is unable to meet the control system online needs apparently. In this paper, the method of soft model technology is used to predict COD.The results show that the intelligent control system established in this paper can control the process of sewage treatment well. The effluent water quality in this control system has improved much. And it has great significance for the stable and efficient operation of the sewage treatment plant.