Realtime control of clarifier

摘要

The solids distribution in clarifier depends on the sludge settling properties, on the transport of bulk liquid and on the eddy turbulence in the settler. A new model is proposed for description of these processes. The Laplace-Poisson equation is used for prediction of the fluid dynamics. A stochastic parabolic quasi-linear differential equation is used for prediction of the solids distribution in the clarifier. The proposed model is approximated in effective computational form as a large system of original stochastic differential equations. This system is solved numerically using sparse matrix technology. The model and calculation algorithm is implemented in the simulation software. The sludge filling process can be simulated and propagation of the stock wave through the settler and effect of turbulent flows on the sludge distribution can be analysed with this realtime simulation software. It can be applied for prediction of the concentration profiles in vertical and horizontal directions. Five control problems are formulated: the sludge blanket control problem, the return sludge concentration control problem, the washout control problem, the sludge-storage control problem and the solids distribution control problem. A general feedback control law is proposed for solution of these problems. The proposed control law is relatively simple. It is suitable for implementation in the wastewater treatment processes.