Multi-objective optimization of integrated water reuse systems at a cluster scale

Abstract

Population growth and higher standards of living have and will continue to drive an increasing demand for water supplies. Past practices have seen conventional water sources diminish which has lead to environmental degradation. Although seen as unconventional in the past, alternative water sources must now be considered for non-potable usage if these increasing demand requirements are to be met. Sources such as reclaimed stormwater, wastewater and rainwater are available to some extent in all communities, but further research is required to identify which single option or combination of these options is best. To assess these different options it is necessary to determine evaluation criteria that reflect the cost, environmental impacts and hence sustainability of these systems. This research aims to investigate different water sources: reclaimed stormwater, greywater reuse, rainwater and various combinations of these, at different urban cluster scales to determine if de-centralised systems have distinct advantages. A sensitivity analysis was used to analyse various components of the system in order to better understand the type of systems that are preferable under different conditions. In order to develop an efficient system design, system components were optimized using a genetic algorithm, a method that has been increasingly used in recent years for this type of application. The results for a particular case study showed that stormwater reuse was preferable to greywater reuse and that a combination of stormwater and rainwater was best overall. Recycled water was also found to be price-competitive when compared to mains water. © 2012 ASCE.