Greywater Reuse Review and Framework for Assessing Greywater Treatment Technologies for Toilet Flushing

Abstract

Increasing impacts of climate change, development and urbanisation on water resource availability have promoted increased water reuse and recycling. This paper achieves two objectives: Firstly, it presents an extensive review of greywater characteristics, treatment technologies and risks, and secondly, it presents the development of a framework for holistically assessing different greywater treatment technologies in order to select the most appropriate for a specific greywater reuse (GWR) application. Addressing these objectives is particularly valuable for South Africa due to the growing interest in greywater reuse (especially for irrigation, toilet flushing and a variety of non-domestic applications), the scarcity of guideline documents to facilitate optimal GWR, and the proliferation of package plants purporting to treat grey/waste water to acceptable quality for use in certain non-potable applications. The developed framework was employed to assess 10 commercially available greywater treatment systems in South Africa using sustainability criteria (social, environmental and economical) and thus mitigated the risks associated with choosing an inappropriate system for toilet flushing at 2 GWR pilot sites. Three of the 10 package plants emerged with favourable scores and the preferred was selected based on simplicity of treatment technology, ease to implement, ease to maintain and cost, amongst other factors.