The spread of health-hazardous PFAS substances has become an increasingly important issue. In a new ex-job at Norconsult Sweden, Felicia Hagberg, a master’s student in the MSc program in environmental and water technology at Uppsala University, has taken a closer look at target values and possible measures for PFAS-contaminated stormwater.
Per- and polyfluorinated alkyl substances (PFAS) are a group of approximately 10,000 different substances that are used, among other things, for the impregnation of textiles and paper packaging, ski wax, cosmetics, fire foam and water and grease repellents. Studies have shown that some PFAS are dangerous to health and, among other things, affect the hormonal system and the immune system. The substances do not break down naturally in the environment, which means that they are today scattered in soil, surface water, groundwater and storm water.
– The substances are transported, among other things, via stormwater, which can pose a risk of spreading to receiving watercourses that are sometimes used as a drinking water resource. In urban environments, stormwater is generally diverted away via wells, ditches and pipe networks and then discharged into nearby receivers without any form of purification, says Felicia Hagberg.
The most risky route of exposure for humans is through ingestion of food and drinking water. In order to limit intake, there are therefore guideline values that determine how high a content of PFAS food or drinking water may contain. Guideline values also exist for PFAS in surface water. For stormwater, however, there are no national guidelines. There is also no standardized stated methodology for producing target values.
– This means that a responsibility is placed on municipalities when developing strategies and action plans for stormwater management, something that they are asked to do within the framework of Sweden’s environmental goals. The purpose of my ex-job was to investigate guideline values and possible measures for PFAS-contaminated stormwater. This has been carried out through a literature study of ten advanced purification techniques for PFAS-contaminated water, as well as a case study of a stormwater system in Sweden, says Felicia Hagberg.
The techniques that in the ex-job were judged to be suitable for stormwater treatment were foam fractionation, activated carbon and ion exchange masses. PFAS consists of a carbon chain that can have different lengths, which gives the different substances varying properties. It is common practice to divide the substance into two groups based on the length of the carbon chain, long and short PFAS.
– The techniques show a good cleaning ability of long-chain PFAS substances, which proved to have the greatest effect in the investigated stormwater system to achieve a sufficiently good separation of PFAS, based on proposed environmental quality standards for surface water in the EU’s water directive. The selection was also based on the criteria water matrix, estimates of costs, energy needs and availability on the market, says Felicia Hagberg.
There are currently few studies that have investigated the purification of PFAS-contaminated stormwater. Erik Ribeli, environmental consultant at Norconsult and supervisor of the degree project, hopes that the results can contribute to filling this knowledge gap.
– We hope that this will be a step on the way to a national strategy on the management of PFAS in stormwater systems. The fact that there are no clear reference values at the moment leads to uncertainties in the assessment of the measured load, he says.
Cecilia Kö[email protected]
Norconsult is one of the Nordics’ leading consulting companies in civil engineering that combines engineering, architecture and digital expertise in projects of all sizes, for private and public clients. Through innovation and collaboration, and with our purpose “Every day we improve everyday life”, we are constantly looking for sustainable, efficient and socially beneficial solutions. With approximately 6,200 employees in over 130 offices in Norway, Sweden, Denmark, Iceland, Poland and Finland, we combine cross-disciplinary expertise with local presence.
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