Abstract

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.

Nomenclature

C

concentration of contaminant (ppm)

f

component flowrate (g/h)

F

water flowrate (ton/h)

in

at inlet

out

at outlet

j

process j

P_j

precursors of j

R_j

receivers of j

min

minimum

max

maximum

*

additional sources

w

fresh water

Article Outline

Nomenclature

1. Introduction

2. Problem statement

2.1. Definitions

3. Necessary conditions of optimality

4. Algorithmic design method

5. Examples

5.1. Example 1

5.2. Example 2

6. Multicomponent systems

7. Conclusions

Acknowledgements

References

¹ Present address: Rowan University, Chemical Engineering Department, 328 Henry M. Rowan Hall, Glassboro, NJ 08028, USA.

Corresponding author. Tel.: +1-405-325-5458; fax: +1-405-325-5813; email: bagajewicz@ou.edu