The Research On Reduction, Control And Optimization Of ASM2

In the wastewater treatment processes, the activated sludge method is a mostly useful method. The activated sludge model series, which are proposed by International Water Association, are the mechanism models corresponding to the activated sludge process. In the series, Activated Sludge Model No.2(ASM2) describes the dynamic processes of COD, BOD, nitrogen and phourospher removal in the activated sludge process. Therefore, the ASM2 is abroadly used in the industrial and municipal wastewater treatment.Firstly, the status quo of the activated sludge model and the industrial application ofthe activated sludge method is summarized. Secondly, the Activated Sludge Model NO.2(ASM2) is described detailedly, and based on ASM2, a whole mechanism model of a typical A~2/O treatment process is established. Thirdly, the reduction of ASM2 is researched. In allusion to the multi-scale of ASM2, we apply the time-scale decomposition method to get a reduced nonlinear model—a group of differential algebra equations. As to nonlinearity of ASM2, we introduce the clustering and PLS algorithm to get multi linear models suitable for model predictive control. Fourthly, the generalized predictive control(GPC) algorithm is applied in the A~2/O process, In the predictive control, dissolved oxygen concentration and sludge refluence are used as manipulated variables, the ammonia and nitrate concentration in the effluent are used as output variables, and the multi models from the third section are used as the predictive model. Lastly, based on many correlative papers, an index measures the economic capacity of the A~2/O process is obtained. The index is then absorbed in the objective function of the predictive control, and the objective is changed into the energy cost saving when the effluent quality is up to par. The objective function is constituted of two levels: the upper level is about the effluent quality, and the appropriate output is then used as a constraint of the lower level which is about the economic capacity. The simulation result shows that the predictive control considering economic capacity helps to save the energy cost in the wastewater treatment process while the effluent quality according with standard.