Waste water treatment calculation on the basis of express model

Abstract

Purpose. The purpose of the work is to develop a numerical model for calculating the efficiency of wastewater treatment in a sump. The developed numerical model can be applied to simulate the velocity field and pollutant transfer in treatment facilities, taking into account their geometric shape and in the presence of additional elements inside the facility. Methodology. For mathematical modeling of the wastewater treatment process in the sump, the fundamental equations of continuum mechanics are used. To calculate the velocity field in a horizontal settler, a model of irrotational flows of an ideal fluid (potential flow model) is used. The construction of the field of impurity concentration in a horizontal sump is based on the numerical solution of the mass transfer equation. This equation takes into account the transport of impurities by convection and due to diffusion transport. For the numerical integration of the equation for the velocity potential, a two-step conditional approximation scheme is used. Numerical integration of the mass transfer equation is carried out using a finite-difference splitting scheme. Previously, the modeling equation of mass transfer is split into two equations. The first equation describes the transport of impurities due to convection. The second equation describes the transfer of impurities due to diffusion. For each equation, a difference scheme of numerical integration is constructed in such a way that at each step the unknown value of the impurity concentration is calculated using an explicit formula. The results. A software package was developed on the basis of the constructed numerical model. The software package makes it possible to quickly calculate the field of impurity concentration in the horizontal settler and the cleaning efficiency. The paper presents the results of calculations to determine the efficiency of wastewater treatment in a horizontal settling tank inside which additional structural elements are located, which affect the flow hydrodynamics. Scientific novelty. A fast calculating numerical model has been developed for calculating the process of mass transfer of an impurity contained in wastewater in a horizontal settling tank. The horizontal sump has additional structural elements. The constructed numerical model makes it possible to calculate the process of mass transfer in sedimentation tanks with a complex geometric shape, an uneven field of wastewater flow velocity in a treatment plant, and diffusion. Practical significance. The developed numerical model makes it possible to evaluate the efficiency of the horizontal sump robots in real time. The numerical model can be used for serial calculations at the design stage of wastewater treatment facilities.