Domestic Sewage Simultaneous Nitrogen And Phosphorus Removal Processing Procedure Control System Research

With the continuous development of society,various environmental problems have become increasingly prominent,and the protection of water resources has become more urgent.Sewage treatment is related to residents' water quality and water safety,which is an urgent problem to be solved in the current urban development in China.Sewage treatment process often involves problems at different levels such as material transport,physical dissolution,microbial biochemical reactions,and especially complex chemical and biochemical reaction processes.Effective control of them has always been an important issue of concern for wastewater treatment.Aiming at the problems of multiple disturbances,non-linearity,strong coupling,and large lag in the simultaneous phosphorus and denitrification wastewater treatment process,the paper conducts research on the control technology of key process processes,mainly completing the following research tasks:First,a dynamic model of the simultaneous phosphorus and nitrogen removal process was established.The main technology and characteristics of wastewater treatment are discussed,and the main process of wastewater treatment of this process is analyzed for the simultaneous removal of phosphorus and nitrogen,the input variables and output variables of each process link are clarified,and the system model is derived for subsequent analysis And control system design provide theoretical basis.Aiming at the problem of time lag in the system,Smith predictor is used to compensate the time lag and improve the dynamic response of the system.Because the sewage treatment process uses multiple bioreactors connected in series,the material transfer process brings a large time lag,reduces the stability margin of the system,and affects the stability of the control system.It is required to know the lag time when using the Smith estimator,but the actual lag time is often difficult to obtain.This paper proposes a lag time prediction method based on the characteristics of the system,which guarantees the effectiveness of the Smith estimator.Due to the problems of large disturbance and parameter time in the wastewater treatment process,a fuzzy PID controller was studied,which effectively improved the performance of the controller.The parameters of the traditional PID controller are fixed,and it is difficult to ensure satisfactory control results under different working conditions.The fuzzy controller is used to modify the parameters of the PID controller in real time to ensure the stability of the control system and continuously improve the control performance.It has the characteristics of intelligent control.Finally,a pilot-scale simultaneous phosphorus and nitrogen removal test system was established to achieve Smith estimation control of dissolved oxygen and total nitrogen control based on fuzzy PID.The system uses a programmable controller as the control platform,develops the corresponding control program,and completes the process test.Process tests were conducted using domestic sewage,and the results showed that the process specifications required for the discharge were achieved.