Multi-objective optimization of wastewater treatment process was studied.According to a nonlinear dynamic model of wastewater treatment process

a multi-objective optimization model was established.The economic cost and integral square error between actual and desired outputs were optimized simultaneously to perform a wastewater treatment plant.The original multi-objective nonlinear problem describing the process optimization of a wastewater treatment plant was first transformed into a multi-objective linear programming by using the indirect optimization method(IOM).A powerful multi-objective optimization genetic algorithm was used to derive the Pareto optimal solutions

which could illustrate the whole trade-off relationships between objectives.The approach proposed not only obtained the approximate Pareto fronts of multi-objective optimization problem

but also had a low computational burden due to the use of multi-objective linear programming method.