Comparative numerical analysis of identification problems related to nonlinear transport-diffusion model of a settler.

Identification problems related to age dependent models of a settling process in the secondary settler of a wastewater treatment plant are considered. The basic model is governed by the nonlinear parabolic equationdescribing the scalar conservation law for the density of sludge mass, and by a nonlocal (integral form) additional condition. The problem is formulated as an identification problem, where the sludge concentrationis assumed to be a control. The mathematical analysis, based on the weak solution theory of PDEs, of the basic model shows the degree of sensitivity of the solutionof the parabolic equation with respect to the coefficient. The results obtained here are then applied to two widely accepted settling velocity models (and). An effective iteration algorithm for numerical solution of identification problems related to these models is proposed. The algorithm is tested for the both settling velocity models. Computational simulation permits one to show an influence of the settling velocity models to the behavior of the sludge concentration. [ABSTRACT FROM AUTHOR]