An invasive weed, farm waste, and a US Air Force pollution problem: Scientists are testing one unlikely solution

A carbon-rich material made by heating biomass could offer a new way to tackle one of the most persistent pollution problems found at US military facilities — and scientists are now investigating how the same type of material can be engineered from agricultural waste and even an invasive weed.

The research centres on biochar, a carbon-rich material produced by heating plant or other biomass under controlled conditions.

A NEW POTENTIAL

In a study published in 'Environmental Science & Technology' in February 2026 under the title 'Leaching of PFOS and PFBS to Groundwater at US Air Force Bases: Could Biochar Offer an Effective Mitigation Strategy?', researchers from the US Department of Agriculture's Agricultural Research Service examined the problem of PFAS contamination associated with US Air Force bases. They noted that the use of aqueous film-forming foams at military facilities can contaminate soil and groundwater with PFAS, particularly around testing and training areas.


The researchers then tested whether biochar incorporated into contaminated soil could prevent two PFAS chemicals (PFOS and PFBS) from moving downward towards groundwater.

THE BIG FINDING

The result was striking in laboratory soil-column experiments. A wood-based biochar produced at temperatures above 900°C, when added to sandy-loam soil at 1% by mass, retained more than 99% of PFOS. A further 400°C thermal treatment of the biochar in air produced essentially non-detectable PFBS levels in the column leachate.

But the study does not mean Air Force bases are already using biochar to clean up PFAS contamination. The experiments were conducted under controlled laboratory conditions. The researchers described carefully selected biochars as a potentially low-cost approach to protecting groundwater at contaminated military facilities.

TWO STUDIES, ONE BROADER RESEARCH QUESTION

A USDA research programme is also investigating another unusual use of biochar — this time involving black mustard (Brassica nigra).

In earlier research, scientists converted different biomass sources into biochar and compared their ability to capture DNA from water. The black-mustard research specifically tested manure, black mustard, orange peel, macadamia nutshell and pine pellet biochars at 500°C. Black mustard showed the strongest DNA adsorption performance, while the 2026 PFAS work identified particular properties and thermal treatment conditions that made wood biochar effective for PFOS/PFBS retention.

The work has now expanded. A June 2026 USDA-listed study examined the interaction between 24 different biochars, feedstock types and pyrolysis temperatures during wastewater treatment. The researchers found that biochar performance varied substantially depending on both the biomass used and the temperature at which it was produced.

That distinction matters because the two studies are not the same experiment. The Air Force-related research used a wood-based biochar to investigate PFOS and PFBS retention in soil, while the wastewater research examines biochars made from different feedstocks for capturing genetic material.

What links them is the broader question being pursued by the USDA team: can biomass-derived biochar be engineered to trap different contaminants before they reach groundwater, crops or the wider environment?

For now, the evidence remains experimental. But the research is turning an otherwise ordinary material — carbon-rich biomass — into a potential tool for tackling some decidedly modern pollution problems, from PFAS at military sites to antibiotic-resistance-related genetic material in wastewater.