Online solution to monitoring water micropollutants
Micropollutants – chemicals found in water at very low concentrations – come from a range of sources. These include pharmaceuticals and shampoos, as well as plastics and pesticides. “Water and waste water treatment plants cannot always identify and remove these micropollutants,” explains ECO-SOS project coordinator Harsha Ratnaweera from the Norwegian University of Life Sciences. “When this happens, they can accumulate in water bodies, or even in the tissue of fish and mussels. This presents potential environmental risks and health problems.”
Challenge of finding micropollutants
The EU-funded ECO-SOS project sought to address this issue by developing novel real-time micropollutant monitoring systems. The goal was to apply intelligent computational estimation techniques to data gathered by affordable and readily available physical online sensors. “Current tools used to find micropollutants are often expensive, time-consuming and complex,” notes Ratnaweera. “It’s a little like looking for a needle in a haystack.” Ratnaweera and his team therefore wanted to see if intelligent software sensors could spot micropollutants in a more efficient way. Water samples taken from a treatment plant in Norway were monitored and then analysed, using algorithms derived from complex mathematical models. The team also investigated the potential use of spectral probes within software sensor systems. A particular focus here was on measuring per- and polyfluoroalkyl substances (PFAS). PFAS are chemicals used to make fluoropolymer coatings and stain-resistant products, and are among the most concerning micropollutants found in the environment.
Potential of online software sensor systems
Results of the project, which was supported through the Marie Skłodowska-Curie Actions programme, have helped to highlight the sensitivity and potential of online software sensor systems in monitoring and detecting micropollutants. “During our sampling campaign, we found a variety of substances, including pharmaceuticals (which was the primary target), but also phthalates (a plasticiser) and bisphenol A (another plasticiser),” says Ratnaweera. “Most of these substances were present at extremely low concentrations.” An interesting finding was the high frequency of phthalate detection. Some phthalates were detected in the majority of water samples, which suggests that these contaminants should become a primary focus in future monitoring. Measuring PFAS proved more challenging however, because PFAS do not absorb or emit light. The team had to look for indirect ways of measuring these chemicals, including fluorescent signals given off by organic matter present in water. Information gathered from these trials will nonetheless help in the development of future monitoring systems for these contaminants.
Strengthened monitoring and control of micropollutants
Data analysis of the experiments is still ongoing. “Creating software sensors is a time-consuming process that involves validating and handling extensive data sets,” adds Ratnaweera. “This makes it computationally demanding. The low concentration of these pollutants is one of the biggest challenges in software system development.” Nonetheless, Ratnaweera believes that the project has made an important contribution in advancing our knowledge of data analysis, as well as the development of software sensors for detecting micropollutants in water. This could certainly be important in the near future, especially if authorities and water agencies are required to strengthen their monitoring and control of micropollutants.
Keywords
ECO-SOS, micropollutants, sensors, contaminants, waste water, PFAS, phthalates
