A New Design Method for Water-Using Networks of Multiple Contaminants with the Concentration Potential Concepts

Water-using processes can be classified as either fixed flowrate operations or fixed contaminant load ones. This article presents a new design method for the water-using networks involving both fixed flowrate operations and fixed contaminant load ones. The definitions of the concentration potential concepts (Liu et al., 2009b, AIChE J. 55, 374–381) are improved to deal with recycling operation in the design. The values of the Concentration Potential of Demands (CPDs) are used as the key factor to determine the performing order: the process with the lowest CPD value will be performed first. While satisfying a demand stream, the internal source streams with descending order of the maximum quasi-allocation amounts will be considered first, and the external source streams will be chosen by the concentrations of the key contaminant (for fixed flowrate operation) or the minimum required amount (for fixed contaminant load operation). The results of a few illustrated examples show that the amounts of freshwater consumptions obtained in this work are close to the best results obtained using mathematical programming methods in the literature, and the calculation of the proposed method is simple.