Optimal Control of an Ultraviolet Water Disinfection System

Abstract

The ultraviolet water disinfection process has numerous advantages in comparison with other water treatments. This study deals with this process’s optimal control and presents all its stages, from problem statement to analysis of results. We consider a typical disinfection water system and data presented in the literature. In this case, the control inputs are the water flow rate and the UV light intensity. A nonlinear dynamic model for the UV disinfection system is constructed and generates a method to calculate the bacterial reduction. An optimal control problem (OCP) is stated using the dynamic model and two optimal criteria: the disinfection and energy criterion. The optimal solutions are yielded by a metaheuristic algorithm based on hybrid topology particle swarm optimization. The algorithm determines the optimal flow rate and light intensity for an imposed bacterial reduction. The implemented program was carried out for a wide range of input values for comprehensive analysis. The analysis of the results establishes when an optimal solution exists and the extent to which the disinfection or energy criterion is fulfilled. The method to calculate the bacterial reduction, OCP statement, optimization algorithm, and results’ analysis may be considered findings of this work.