Dynamic Modeling And Controller Design For Biological Treatment Of Wastewater

Wastewater treatment process is characterized as high nonlinearity and random changes in the flow,at the same time the lack of precise biological sensors makes some important variables is difficult or cannot be measured online.Therefore,the modeling,observation and controller design of wastewater biological treatment process havevital significance.This research takes wastewater continuous flow reactor as the research object,and studies the dynamics behavior of wastewater biological treatment process from modeling,analysis and control theory.The main content can be divided into the following two parts:Firstly,to meet the discharge standard of wastewater,the way of wastewater flowsin and out the reactor is constrained.The one way is to replacethe original continuous mode by pulse injection and discharge one,based on the impulse mode,a state feedback bioreactor model is established,and the dynamic characteristic of the model is analyzed by means of the related theories of impulsive system,especially the existence and stability of periodic solution,and with the aid of periodic behavior,the model parameters are optimized with the pollutant emissions as the optimization goal.The second way is to replace the continuous mode by flow in switch one,based on this mode,a bioreactor model based on variable structure control model is established,the qualitative analysis of the model is carried out with the aid of related theory of Filippov systems,and the existence of sliding mode and the corresponding dynamics are discussed.Secondly,in order to achieve the goal of wastewater concentration in the reactortracing a given emission levels rapidly,the control of bioreactor is studied.In the first design,the microorganism injection concentration is chosen as the control input,by considering the biomass cannot be detected online and real-time,feedback linearization controller and the back-stepping controllers are designed based on Lebesgue observer,which can realize the tracing functionality of wastewater concentration.In the second design,the bioreactor dilution rate is selected as the control input,by considering that the biomass cannotbe detected online and real-time and uncertainty of the model,the sliding mode observer is designed,and feedback controller is constructed to realize the tracing functionality of wastewater concentration.At last,MATLAB software is used for numerical simulation and the simulation results verify the effectiveness of the proposed method.