Optimization of wastewater treatment plant operation for greenhouse gas mitigation

•We present a multi-objective optimization of wastewater treatment plant operation.•The optimization considered greenhouse gas emissions, cost, and effluent quality.•The wastewater treatment model predicts all three major greenhouse gas emissions.•The nonlinear optimization problem was solved with the Nelder–Mead Simplex method.•Compared to a base case, the three criteria were reduced by 31%, 11%, and 2%.

This study deals with the determination of optimal operation of a wastewater treatment system for minimizing greenhouse gas emissions, operating costs, and pollution loads in the effluent. To do this, an integrated performance index that includes three objectives was established to assess system performance. The ASMN_G model was used to perform system optimization aimed at determining a set of operational parameters that can satisfy three different objectives. The complex nonlinear optimization problem was simulated using the Nelder–Mead Simplex optimization algorithm. A sensitivity analysis was performed to identify influential operational parameters on system performance. The results obtained from the optimization simulations for six scenarios demonstrated that there are apparent trade-offs among the three conflicting objectives. The best optimized system simultaneously reduced greenhouse gas emissions by 31%, reduced operating cost by 11%, and improved effluent quality by 2% compared to the base case operation.