Multi-objectiveWaste LoadAllocation in RiverSystembyMOPSOAlgorithm

Document Type : Original Research Paper


Graduate Faculty of Environment, Department of Environmental Engineering, University of Tehran,P.O.Box 14155-6135, Iran


This paper explores the capabilities of Multi-objective Particle Swarm Optimization algorithm
in a simulation-optimization model for solving waste load allocation problems. The main goals are total
treatment costs, violation of the water quality standards and equity. In this research, the water quality
simulation model is coupled with a multi-objective optimization model, MOPSO. In order to derive nondominated
solutions, two different optimization models are used. The first is referred to as the cost versus
quality model and the second one also consider minimizing cost and inequity. For the each case, the trade-off
curve (Pareto front) is derived and the best non-dominated solution on the trade-off could be selected by
stakeholders and decision makers. The proposed model has been developed for Haraz River in the northern
part of Iran which represented scenarios considering different interests and answered questions to modify
scenarios according to the decision makers’ideas. Solutions were compared with NSGA-II, and the results
demonstrate a suitable convergence and diversity of proposed algorithm.