The implications of household greywater treatment and reuse for municipal wastewater flows and micropollutant loads

An increasing worldwide interest in water recycling technologies such as greywater treatment and reuse suggests that additional research to elucidate the fate of xenobiotics during such practices would be beneficial. In this paper, scenario analyses supported by empirical data are used for highlighting the potential fate of a selection of xenobiotic micropollutants in decentralised greywater treatment systems, and for investigation of the possible implications of greywater recycling for the wider urban water cycle. Potential potable water savings of up to 43% are predicted for greywater recycling based on Danish water use statistics and priority substance monitoring at a greywater treatment plant in Denmark. Adsorption represents an important mechanism for the removal of cadmium, nickel, lead and nonylphenol from influent greywater and therefore the disposal route adopted for the generated sludge can exert a major impact on the overall efficiency and environmental sustainability of greywater treatment.

Research highlights
► The submitted paper investigates the fate of five xenobiotics (cadmium, nickel, lead, benzene and 4-nonylphenol) during greywater treatment.
► As the pressures on potable water supplies continue to increase, particularly in water stressed countries, there is expanding interest in the use of alternative water sources such as recycled greywater.
► Scenario analyses based on Danish water use statistics and priority substance monitoring at a greywater treatment plant in Copenhagen are used to investigate the possible implications of greywater recycling for the wider urban water cycle.
► The potentials for substantial potable water savings are demonstrated as well as reductions in effluent flows to wastewater treatment plants.
► This paper is the first to assess the impacts of greywater treatment on generated micropollutant loadings and highlights the role of generated sludge in influencing the potential overall impact on the wastewater treatment plant.