Effect-based monitoring of water quality in the circular economy

Freshwater from groundwater or surface water sources is becoming scarce in dry periods, driving a rise in interest in the use/re-use of rainwater and treated domestic and industrial wastewater. This requires the consideration of the potential risks resulting from circulating and accumulating microbial and chemical contaminations in partly-closed water cycles, depending on the circumstances in which the water is re-used. It is therefore important to establish a picture of regional-, source- and basin-specific hazards for the safe re-use of water with the aim of controlling potential risks for human health.

Water quality assessment in a circular economy

KWR recently developed the Water Wise concept, an easy-to-use, transparent and consistent evaluation framework as a first step towards the quantitative evaluation of the chemical risks inherent to new water cycles. Research and expert judgement on new water-cycle-related risks are needed to develop the framework further. Depending on the information fed into the tool and the outcome of the Water Wise risk assessment, it is expected that the output will include a recommendation to apply bioassays.

In the current project, ‘Effect-based monitoring of water quality in the circular economy’, a set of bioassays was selected which will be applied to different samples from defined water cycles (such as effluent from wastewater treatment plants, rainwater, and irrigation/sub-irrigation water). DNA damage has been selected as the primary toxicological endpoint because of its relevance for human health by inducing mutations and tumour formation and because well-established in vitro assay protocols for this endpoint are available. Selected assays include the Ames fluctuation test, Umu test, p53 CALUX, micronucleus test, comet assay and ToxTracker.

Effect-based methods

Effect-based methods using in vitro cell models and bacteria (bioassays) provide a powerful instrument for investigating the relevant hazards of complex low-level mixtures in the water cycle without prior information about their chemical composition. In particular, bioassays for investigating DNA damage or endocrine disruption are increasingly being implemented in the water sector in addition to chemical analyses to assess the quality of water sources and the effectiveness of water treatment processes.

This project will deliver bioassay responses for the defined water cycles, along with a proposed strategy for data interpretation and risk assessment in a water re-use context. A next step may be to also consider endocrine disruption and neurotoxicity. In this way, this project supports the implementation of bioassays in the circular economy by creating awareness about the need for hazard and risk assessment for existing and new water cycles.