Compost worms could help reclaim brownfield sites

Brownfield sites are a prime area for redevelopment, either by providing land for new renewable energy projects or space for new buildings, and a Washington State-based chemicals company has come up with a simple but clever way to remediate them.

Organix, Inc is planning to deploy billion of worms at a dairy wastewater site in Walla Walla in the hopes that worms, which are often used in composting, can help absorb the toxic chemicals and organic waste that is often left behind in similar land.

Read more: Disused New Hampshire landfill could help a town reach net-zero

After 18 months of action, the filter has left behind thousands of yards of land in need of cleaning up, which is where the worms come in.

Following the composting, the owners of the land can then "amend" the soil, allowing it to be used for other developments as if it had never been previously built on.

“There is no question among the scientific community; vermiremediation always works at some level,” claims Russ Davis, President of Organix.

“The goal is to determine what the potential is and define the methodologies and protocols required to maximise effectiveness at a commercial scale for remediation.

"It’s hard to get much greener than worms for soil remediation – worms are a primary contributor to what makes soil biologically viable,” he added.

The US Federal Government is looking into greener methods for remediation - or remedying - of land. In early 2022 the Environmental Protection Agency (EPA) updated its guidelines on the process, which can stop potential harmful chemicals, or other kinds of dangers leftover from industrial use, from affecting local communities.

Remediation simply refers to removing harmful substances from anything following use, be it land, water or sediment. It is considered a vital step in helping reclaim the land or use or stopping it from harming local ecosystems.

Brownfield sites have long been touted as a prime area for redevelopment and could provide crucial land in the energy transition for the construction of new onshore renewable energy projects.

The most common types of brownfield sites include disused factories, landfills and petrol or gas stations.

Early trials conducted by Organix suggest as many as 95-98% of Polychlorinated biphenyls (PCBs) - a toxin banned in the US in 1978 - are removed from wastewater by the process. Further trials are expected to test its viability.

The firm currently boasts "20,000 yards of vermisubstrate" across its operations and claims to have processed around 4 billion tonnes of organic material since its founding in 2001. "Vermi" is short form for vermiform, meaning worm and substrate being the base for which the worms live, in this case, soil.

“Our goal is to determine how many contaminants we can either break down, sequester, contain, or control. Aside from PCBs, we are also targeting various hydrocarbons," Davis added.

The firm typically uses two methods to remove toxins from wastewater: using the worms in a biofilter or employing vermisubstrate taken from a non-polluted source.

Read more: Next 5 years "critical" for plastics sector to go circular & decarbonise

The firm ultimately hopes this type of remediation can be used on a larger scale to prepare brownfield sites for redevelopment. This will also allow sites to be remediated, which could lead to even more land available for reuse within a timely manner

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