Design of water utilization systems in process plants with a single contaminant

This paper illustrates necessary conditions of optimality for single component water-using networks in process plants. These necessary conditions correspond to the optimal water allocation planning (WAP) problem that considers wastewater reuse on the basis of a single contaminant and where the objective is to minimize the total water intake. The conditions under which degenerate solutions are possible are also identified. Examples are discussed. A method that can be implemented by hand is also provided.