Superstructure Development and Optimization under Uncertainty for Design & Retrofit of Municipal Wastewater Treatment Plants.

In this contribution, an optimization - based approach is presented for optimal process selection and design for domestic wastewater treatment plant s (WWTP s ). In particular, we address the issue of uncertainties by formulating the WWTP design problem as a Stochastic Mixed Integer (Non) Linear Programming (sMI (N) LP) problem , which is then solved to determine the optimal process selection and flow diagram (i.e. the interconnection between process units) that meet s a set of performance criteria including effluent quality requirements , cost and technical requirements. The application of the fr amework is highlighted using a case study aiming at designing a new WWTP under different objective function scenarios. For the uncertainty analysis, sources related to influent wastewater composition, operational cost and effluent permit requirements are s tudied and robust design candidates are generated and discussed.