Water is threatened: Toxins leak through purification

Around the world, thousands of biofilter facilities have been built in cities to purify stormwater. Now, Swedish researchers see a risk that the technology is failing, and that toxic PFAS can flow right through. This is a major risk for us and for the environment, says researcher Ali Beryani at Luleå University of Technology.

» Published: October 11 2024

Water is threatened: Toxins leak through purification
Photo: Anders Humlebo/TT

Share this article

PhD student Ali Beryani has, together with the construction company NCC and researchers at Ohio State University, investigated 20 so-called biofilters in the USA.

Passing through the filter

Biofilter purification is a relatively inexpensive and smooth way to purify rainwater, and is based on the same principle worldwide. Rainwater is collected and allowed to flow through a biofilter, which can consist of sand, for example. Dirt and pollutants are left behind in the filter before the water eventually flows out into watercourses.

However, researchers have not previously known how well biofilters are at collecting PFAS, the so-called "forever chemicals". These potentially toxic, highly fluorinated and slowly degradable substances come from everything from firefighting foam to clothing and cars, and can follow the rainwater.

Beryani and his colleagues found a large amount of PFAS in the biofilter facilities, but not just at the top, where most pollutants are collected, but in all layers. The fact that the molecules follow the water through the filter layers probably means that some follow the water out into watercourses and the environment.

New filters may be needed

Above all, the use of PFAS should be reduced, since these substances are so difficult to purify. And if biofilters are to be more effective at capturing PFAS, thousands of existing facilities may need to be adapted. It may also be necessary to add substances that are better at absorbing PFAS, such as activated carbon or iron, or to review the type of sand used.

In the next study I'm working on now, we'll look at exactly how effective additives can affect pollutants, says Beryani.

Probably, the solutions will look different in different places, depending on the types of PFAS present.

They should be targeted, because there is no single solution that magically works for all pollutants, since there are so many different ones in rainwater, he says.

The study has been published in the scientific journal Environment Science & Technology.

PFAS are human-made chemicals that break down extremely slowly and therefore accumulate in nature and in our bodies. Some are toxic and can increase the risk of various negative health effects.

PFAS have been manufactured since the 1950s and are, among other things, dirt- and fat-repellent. They are found in everything from makeup, impregnation, popcorn bags, firefighting foam, and solar cells.

PFAS do not occur naturally in nature, but are now found everywhere. For example, millions of Europeans may be exposed to high levels in their drinking water.

Source: The Chemicals Agency

In the study, 20 biofilter facilities in the US states of Ohio, Michigan, and Kentucky, which have been in operation between 8 and 16 years, were investigated.

A biofilter facility consists of approximately one meter of, for example, soil or sand, which collects rainwater from, among other things, rain. The water flows through the filter layers, where pollutants are left behind. At the bottom, the purified water is collected and led further into the piping network and out into lakes and watercourses.

The study has been published in the scientific journal Environment Science & Technology.

Tags

Author

TTT
By TTEnglish edition by Sweden Herald, adapted for local and international readers

More news

Car and Train Collision in Skene Injures Two
1 MIN READ

Car and Train Collision in Skene Injures Two

Magnet Fisherman Discovers Suspicious Object Prompting Police Action
1 MIN READ

Magnet Fisherman Discovers Suspicious Object Prompting Police Action

Beware of Deceptive Mushrooms: Avoid These Common Mistakes
2 MIN READ

Beware of Deceptive Mushrooms: Avoid These Common Mistakes

Teen Detained in Connection to Kallhäll Double Murder
1 MIN READ

Teen Detained in Connection to Kallhäll Double Murder

Firefighter Injured in Fatal Accident Rescue Near Norrköping
1 MIN READ

Firefighter Injured in Fatal Accident Rescue Near Norrköping

Gällivare Hospital in Emergency Mode Due to Mobile Network Outage
1 MIN READ

Gällivare Hospital in Emergency Mode Due to Mobile Network Outage

Dad Misplaces Baby in Stroller Now Suspected of Crime
1 MIN READ

Dad Misplaces Baby in Stroller Now Suspected of Crime

Major Fire in Upplands Bro Leaves Dozens Homeless
2 MIN READ

Major Fire in Upplands Bro Leaves Dozens Homeless

TikTok Targets Youth Engagement in Sweden's Church Election
2 MIN READ

TikTok Targets Youth Engagement in Sweden's Church Election

Åkesson: Church Should Avoid Taking Sides on Gaza Conflict
3 MIN READ

Åkesson: Church Should Avoid Taking Sides on Gaza Conflict

Dousa Criticizes Stegrud's Comment on Swedish Cultural Debate
2 MIN READ

Dousa Criticizes Stegrud's Comment on Swedish Cultural Debate

Volunteer Air Corps Mourns Pilots After Fatal Crash in Norrtälje
3 MIN READ

Volunteer Air Corps Mourns Pilots After Fatal Crash in Norrtälje

Shooting at Alby Subway Station During Rush Hour Leaves Man Injured
2 MIN READ

Shooting at Alby Subway Station During Rush Hour Leaves Man Injured

Experts Warn Against Unnecessary Menopause Tests and Treatments
3 MIN READ

Experts Warn Against Unnecessary Menopause Tests and Treatments

Mohamsson Criticizes Busch's Call to Move Swedish Embassy to Jerusalem
1 MIN READ

Mohamsson Criticizes Busch's Call to Move Swedish Embassy to Jerusalem

Woman Falls from Balcony in Helsingborg; Man Arrested for Attempted Murder
1 MIN READ

Woman Falls from Balcony in Helsingborg; Man Arrested for Attempted Murder

Explosion Reported at Järfälla Apartment Building
1 MIN READ

Explosion Reported at Järfälla Apartment Building

Explosion Reported at Row House in Södertälje, Police Investigate
1 MIN READ

Explosion Reported at Row House in Södertälje, Police Investigate

Woman Found Dead in Helsingborg Apartment Man Arrested
1 MIN READ

Woman Found Dead in Helsingborg Apartment Man Arrested

Russian Signal Disruptions Threaten Air Safety in Europe
1 MIN READ

Russian Signal Disruptions Threaten Air Safety in Europe