Optimal Synthesis of Water Networks for Addressing High-Concentration Wastewater in Coal-Based Chemical Plants

This paper outlines the development of an optimization-based method for synthesizing a water network, which incorporates various treatment technologies to address the high-concentration wastewater in coal-based chemical plants. One important feature of the proposed approach is that it associates a multistep wastewater treatment design within a source-regeneration-sink superstructure. This design can enforce certain design and structural specifications to tighten the model formulation and enhance solution convergence. A mixed integer nonlinear programming problem is formulated based on the proposed superstructure, which involves unit-specific shortcut models instead of the fixed impurities removal model to describe it accurately. The proposed method for water network synthesis is demonstrated using two case studies, which determine the effect of streams composition and wastewater treatment technologies on the total network cost, freshwater consumption, and water network design. The results highlight the ability of the proposed model for the developed water network synthesis by computing quickly and realizing the goals of cost savings and discharge reduction.