Water network integration as an important water conservation technology has attracted more and more attention. The fixed flowrate operation and fixed contaminant load operation are two typical processes in industrial practice. Different from fixed contaminant load operations

fixed flowrate operations are the quantity controlled units that do not involve mass transfer. To consider recycling

this paper improves the concepts of the concentration potentials，which were proposed in the literature for fixed contaminant load systems with multiple contaminants. The improved concepts can be applied to targeting and design for the water system with multiple contaminants of fixed flowrate processes. In the design procedure

the performing order is determined by the values of concentration potential of demands (CPDs): the process with the lowest CPD value should be performed first. While satisfying a demand stream

the internal sources streams with descending order of maximum quasi-allocation amounts will be considered first

and the external sources with descending order of cost will be used in turn. The results of the illustrated examples show that the method proposed can design fixed flowrate networks with multi-contaminant easily. It is shown that the proposed method is simple and effective.