Design of distributed wastewater treatment networks of multiple contaminants with maximum inlet concentration constraints

We present a heuristic rule-based method for the design of distributed wastewater treatment networks of multiple contaminants with maximum inlet concentration constraints, based on the insight that one of the important essences of distributed wastewater system integration is to reduce the total treatment flow rate by minimizing unnecessary mixing amount of streams. The design procedure includes the following main steps: (1) selecting treatment processes; (2) determining the precedence order of the selected processes; (3) developing initial network structure(s) and identifying key contaminant(s); (4) obtaining the final design by considering maximum inlet concentration constraints, contaminant mass load balances, and identification of the pinch point simultaneously. To meet maximum inlet concentration constraints or environmental regulations, some treatment process(es) might take recycling structure. The results of three literature examples demonstrate that the designs obtained with the proposed method are comparable to those obtained with mathematical programming approach. It is shown that the proposed method is simple and of clear physical insight. (C) 2016 Elsevier Ltd. All rights reserved.