Presence and fate of priority substance dynamics in domestic greywater treatment and reuse systems.

A vast number of household sources may potentially contribute to greywater contaminant loads. This paper investigates the sources, presence and potential fate of a selection of xenobiotic organic compounds (listed under the European Water Framework Directive as ‘Priority Substances’) in onsite greywater treatment systems. Significant knowledge gaps are identified. A wide range of potential treatment trains are available for greywater treatment and reuse but information regarding the treatment efficiency of priority substances in these systems is almost wholly lacking. Geochemical modelling indicates that priority substance removal during treatment is likely to be predominantly due to sludge/ solid phase adsorption. Since the majority of automated greywater treatment plants periodically discharge sludge to sewers, most systems are likely to be of limited benefit in terms of overall source control. Hence, it is important to ensure that other source control options (e.g. green labeling, green procurement, information campaigns, substance substitution, and regulatory controls) continue to be pursued, in order that greywater recycling can continue to reduce the burden on potable water supplies without presenting further risks to the environment.