Water Treatment Plants Are Ineffective at Removing Forever Chemicals

With ongoing droughts and all-around water shortages impacting crop growth across the globe, using treated wastewater to irrigate fields offers an opportunity to recycle the ever-more scarce resource.

But according to a new study by Penn State, the reuse of the treated water comes with unintended consequences, thanks to the presence of “forever chemicals” in the water.

The team at Penn State took a hard look at PFAS (per-and poly-fluoroalkyl substances), a family of slow-to-break-down synthetic compounds that are nicknamed forever chemicals due to their ability to persist in bodies and environments for years. The chemicals—many of which are endocrine disrupting—can interfere with organisms’ hormone systems and, when present in high concentrations, can lead to disease.

PFAS compounds are commonly used in industrial and manufacturing processes to create things such as non-stick cookware coating, waterproofed materials, food packaging, clothing, furniture and much more. The chemicals have found their way into waterways, food and ecosystems around the world, even in remote areas.

Once PFAS compounds enter the water system, whether from industrial wastewater or households, not even the treatment process can eradicate or remove them. That means when treated wastewater gets used for things such as agricultural irrigation, any PFAS chemicals present in the water can end up being absorbed by plants—and then consumed by us.

For the study, researchers tested concentrations of the chemicals present in water samples at a water reclamation facility. They focused on 10 PFAS compounds across the site, testing water samples for chemical levels on a bi-monthly basis from mid-2019 through the end of 2021—both before and after it was treated.

The results showed that the PFAS compounds were virtually everywhere in both untreated and treated water across the site, complicating the picture when it comes to the benefits of reusing wastewater for crop irrigation.

“Our study results have important implications to ensure that beneficial wastewater reuse activities achieve desired goals to reuse water and nutrients, while simultaneously ensuring PFAS levels are safe from a human health perspective,” said Heather Preisendanz, associate professor of agricultural and biological engineering at Penn State and co-author of the research.

In addition to testing the water for the presence of PFAS chemicals, the team also tested plant matter from nearby crops irrigated with the water from the facility. The team found traces of PFAS compounds not only in the tissue of the crops that were irrigated with the water but also in non-irrigated crops on the same site.

In light of the results of the study, researchers concluded that the full picture of the pros and cons of utilizing treated water for crops needs to be studied further to be truly understood.

“PFAS have been shown to be taken up by crops and enter the food chain when the crops are consumed, so when treated wastewater is used for irrigation activities in agricultural fields, understanding these tradeoffs is of critical importance,” said Preisendanz.