Pinch-based and disjunctive optimization for process integration of wastewater interception with mass and property constraints

In-plant interception is used to adjust the concentrations and properties of multiple wastewater streams containing pollutants and environmentally-undesirable properties. The determination of the pinch point is critical for the determination of optimum design conditions. Algebraic and graphical techniques are used to locate the pinch point. The selection of the appropriate mass separating agent(s) (MSAs) is based on thermodynamic and economic considerations. A screening procedure is applied to screen competing mass separating agents. Mathematical disjunctive programming is proposed to compare alternatives and invoke the proper models when a certain technology is to be utilized. The model minimizes the total annualized cost, which includes the cost of the selected separating agents and the annualized cost of their associated equipment (depreciation). An example is presented to show the applicability and advantages of the proposed models.