25. Model for Optimal Regional Wastewater Systems Planning with Uncertain Wastewater Treatment Capacity

The development of an optimization model for planning regional wastewater systems is centered on reducing the overall costs of wastewater treatment plants (WWTP) locations and sewer layout while taking treatment capacity uncertainty into account. The goal of the model is to reduce overall costs while taking uncertainty into account, with a given degree of reliability, ensuring that the amount of flow to be treated does not exceed the treatment capacity. The model is formulated using a chance-constrained method which have been used for addressing optimization problems with a range of uncertainties. The model is developed in the General Algebraic Modeling System (GAMS) program using Mixed-Integer Linear Programming (MILP), and it is then applied to a simple example utilizing various reliability percentages ranging from 60 to 95%. A simple example demonstrates that employing 60–75% reliability has the same total costs and layout for the system. The system’s layout and overall costs would be higher although, as the reliability value exceeds 80%.