ABSTRACT
ABST R AC T A mathematical programming model for the synthesis of mass exchange networks is presented. The approach considers simultaneously direct recycle-reuse networks together with wastewater treatment processes to provide an optimal structure constrained by a given set of environmental regulations. The model combines both mass and property integration; the latter incorporates in-plant property constraints as well as properties impacting the environment, such as toxicity, theoretical oxygen demand, pH, color, and odor. A disjunctive programming formulation is developed to optimize the recycle/reuse of process streams to units and the performance of wastewater treatment units. The formulation gives rise to a mixed-integer nonlinear programming model, which is used to minimize the total annual cost of the network (cost of fresh sources plus the annualized costs for piping and property interceptors). A numerical application that shows the advantages of this integrated approach with respect to a sequential optimization strategy is included.
