Keeping PFAS in biosolids out of your food

Generally, taking a waste product and using it for a good purpose – like increasing food production – is a good thing. That’s the idea behind biosolid waste that is spread on farmland, commercial gardens and homeowners’ property. But it’s become increasingly clear that there’s a problem, and that problem is PFAS.

Per- and polyfluoroalkyl substances – PFAS — are manufactured chemicals used in firefighting foam, breathable outerwear, fast-food packaging, non-stick cookware and other products (see here to learn more). Increasing concern about the health and environmental impacts of PFAS means that there is a need for keeping these potentially harmful materials isolated.

Here’s why that matters.

We’re talking about two main waste streams:

Wastewater treatment works sludge

Municipal public works use various methods to treat their city’s wastewater, which includes domestic sewage, industrial wastewater and leachate flowing from landfills (more on that here). These facilities purify the wastewater to meet relevant environmental standards. But they’re designed to treat sewage – they’re not equipped to deal with the PFAS in the liquid.

Some of the PFAS slips through the treatment process to be released with the plant’s effluent, into surface water. PFAS can also accumulate in the “sludge,” which is solid or semi-solid material pulled from the waste stream.

In some municipalities, that sludge is sent to a landfill. Others make their sludge available to be spread on farmers’ fields, where it helps improve crop yields. Sludge may also be incorporated into compost used in commercial and personal gardening. In a moment, we’ll look at the implications of these choices.

Domestic organics

The other source of PFAS in biosolids is “green bin” initiatives for curbside collection of food scraps and other organics. This material is then processed into compost that is used on municipal parkland and sold to homeowners and landscapers.

The problem is that the green-bin waste stream often includes wood-derived food packaging such as pizza boxes, cardboard fast-food containers, and paper coffee cups. Much of this packaging contains PFAS, added so that food doesn’t stick to the container or wrapper. But it also means that PFAS contaminates the household-organics waste stream, and ends up in any compost produced from it.

Increased pressure to keep PFAS out of our food

There’s been growing concern that PFAS must not be able to contaminate our water or food supply through the biosolids route. There have been news reports of farmland rendered useless for growing crops or as pasture, because PFAS-impacted sludge was spread on it.

The US-EPA says that when present in biosolids, PFAS can be taken up by plants and crops and/or leach into groundwater, which can be consumed by people and animals or used for agriculture[a].

And governments are taking action. For example in April 2022, the State of Maine became the first state to ban the practice of spreading PFAS-contaminated sewage sludge as fertilizer. The new law also prohibits sludge from being composted with other organic material.

To address PFAS contamination, some locations require collection and treatment of contact water from composting sites that accept food waste or prohibit PFAS in food packaging. Some manufacturers are voluntarily phasing out particular PFAS from food packaging. Compostable food packaging certified by the Biodegradable Products Institute can no longer contain intentionally added fluorinated chemicals.

Stopping the PFAS chain through plasma vortex technology

But the problem of PFAS in biosolids remains.

One solution is to pull the PFAS out of the wastewater stream early in the treatment process. We’ve looked at the various technologies for doing this in a previous blog post.

Onvector’s technology, called plasma vortex, is one of the few proven solutions able to actually destroy PFAS molecules found in wastewater.
This technology destroys PFAS molecules by harnessing the fourth state of matter, plasma. Within the plasma vortex reactor, a voltage gradient is applied between two electrodes. This creates an electric field that strips electrons from the inflowing gas molecules, creating charged ions and releasing a plasma discharge. The ions are highly chemically reactive, and can break down PFAS molecules. This produces harmless by-products like fluoride, sulfate, carbon dioxide and water.

Next step: reach out to us for an exploratory conversation

If you have a PFAS problem you want to solve, please reach out and we’ll have a conversation around whether there’s a fit between what you need and what we can offer. We’re also interested in skilled professionals who might want to join our team.