Passive samplers were used to monitor micropollutants in recycled water from 3 recycled water plants in metropolitan Melbourne. Each plant uses different treatment methods to produce Class A or Class B recycled water. In Victoria, the Environmental Protection Authority (EPA) set criteria for different classes of recycled water based mostly on pathogen levels and intended uses for the water, however there are currently no specific objectives for micropollutants. Micropollutants include pesticides, pharmaceuticals and personal care products (PPCPs), perfluoroalkyl and polyfluoroalkyl substances (PFAS), nanomaterials, plasticisers, and any other organic or inorganic contaminants present at trace concentrations in the environment.
Three different passive samplers were used to screen for a total of 236 micropollutants in recycled water, using LC-MSMS and GC-MSMS methods developed in collaboration with National Measurement Institute and Melbourne Water. The three types were Polar Organic Chemical Integrative Sampler (POCIS) (targets compounds with Log KOW <3), Chemcatcher (SDB-XC) (targets compounds with Log KOW 1-4) and Trimethylpentane containing passive sampler (TRIMPS) (targets compounds with Log KOW >3).
Up to 25 different micropollutants were detected at any individual site, and the numbers were always greater in Class B than Class A recycled water. The most frequently detected micropollutants included fungicides (carbendazim and tebuconazole), herbicides (atrazine, simazine and diuron), insecticides (imidacloprid) and PPCPs (carbamazepine, paracetamol and thiabendazole). Sampling was repeated over multiple seasons at each treatment plant.
Seasonal as well as between-treatment plant differences in micropollutant detections highlight the importance of regular monitoring and consideration of different catchment characteristics. Recycled water has great potential as an alternative water source for many applications, and whilst the results of this study determine presence only, further development of passive sampler methods for quantification of chemicals in recycled water is an effective monitoring strategy to ensure both ecological and human-health risks can be adequately quantified and managed.