Coupled Optimization-Simulation Water Quality Model

One of several considerations in river basin water quality management is determining treatment facilities needed to maintain stream quality standards. To deal with this problem, a stream water quality simulation model is coupled with a treatment cost minimization model. The optimization model is structured as an integer programming problem in which the integer decision variables are wastewater treatment levels to be determined for each discharger. The stream water quality simulation model, which relates pollution loading to stream quality response, generates the coefficients for the constraint equations in the optimization model. The model is applied to an example problem consisting of four pollution discharge points, at which seven possible treatment levels are available to remove four pollutant constituents. Water quality standards are imposed at five control points along the stream. Results of the optimal solution indicate the treatment level to be applied at each discharge point, the minimum total cost, and the stream quality conditions.