In the design of water-using networks of multiple contaminants

there are two key steps: determining the process executing order and allocating the process streams.In this paper

a new concept

overall concentration potential of demand (OCPD)for the process stream is proposed.The OCPD of a stream reflects the concentration order of a stream compared to all the other streams (including both demand streams and source streams）.Compared to the concentration potential concept proposed by Liu et al(2009)

OCPD can compare the concentration order of a demand stream and that of a source stream.In the design

the process executing order is determined by the values of OCPDs of the demand streams.The process with the lowest inlet OCPD is executed first.When satisfying a demand stream of the process being executed

the source stream with the largest quasi-allocation amount

which is defined in this paper

is used first.A few literature examples are investigated.The results show that the amounts of fresh water consumptions are very close to the minimum fresh water targets

the structures of the designs obtained in this work are not complex compared to that obtained in the literature

and the calculation of the proposed method is very simple.