Cascade Models for Targeting and Synthesis of Total Water Networks

Abstract

Success in the race for efficiency means for today’s process industries their survival. The most critical resources are energy and water, with the latter being a crisis factor when in shortage. Effective water savings are achieved by reuse, regeneration and recycling. The selection of regeneration technology cannot be addressed separately from targeting reuse, recycle and fresh water flowrates. This work simulates total water networks as cascade systems, represented by transhipment models and uses a the two step iterative procedure to coordinate the targeting of minimum fresh water requirements, the calculation of recycle and treatment flows and the selection of water treatment processes. The procedure offers the advantage of producing optimal solutions ahead of design by using linear mixed integer models. Two examples from literature are used to illustrate the new approach for single contaminant systems, one with fixed mass loads of contaminant and one with fixed flowrates in water using operations.