With more than 57,000 sites where groundwater is contaminated with per- and polyfluoroalkyl substances (PFAS), an estimated 200 million Americans are exposed to these toxic chemicals simply from drinking their tap water. We need a more effective approach to cleaning up these “forever chemicals” that have been used for decades in firefighting foam, the manufacturing of non-stick pans, fast-food wrappers, waterproof apparel, furniture, and more.
Once PFAS reach groundwater, they are readily transported by it. They do not degrade in the environment like other chemicals, and they can travel for miles down gradient toward public water supply wells, domestic drinking water wells, or surface waters. Exposure to PFAS in drinking water, which can begin even before birth, are likely contributing to an epidemic of chronic health problems.
Of all the possibilities, drinking PFAS-contaminated water offers the most dangerous exposure pathway, since it provides direct access into our bodies where the chemicals can bio-accumulate. With three-to-five-year half-lives measured for some of the more prevalent compounds, almost all of us permanently carry PFAS in our bodies.
The sources of PFAS contamination include seepage from landfills, electronics, airport and military firefighting foams, and plastics. Swift action must be taken to contain the PFAS upstream of public and private drinking water wells to protect them before they become impacted. Thus far, most responses have been emergency-driven, treating the problem at the wellhead after people and communities are exposed.
Currently, the most common method proposed to protect drinking water wells from PFAS pumps the contaminants to the surface, creating waste products and new ways to become exposed while further polluting our atmosphere with greenhouse gases (GHGs). A safer, more effective, sustainable, and more cost-effective alternative that filters PFAS below the surface to prevent exposures has gained attention and is now being implemented on impacted sites worldwide.
Containing PFAS: A Feasible Groundwater Treatment Option
Containing or stopping PFAS movement in groundwater toward public or private water wells is the only feasible groundwater treatment approach. Due to their highly stable chemical structure, PFAS can only be destroyed using a lot of energy, which contributes to more GHG emissions. Consequently, chemical destruction techniques employed for other groundwater contaminants are impractical for treating PFAS. In fact, chemical destruction is not necessary for remediation. Containing PFAS accomplishes the same goal: removing the exposure risk to communities downstream.
The two containment strategies that use carbon to treat PFAS in groundwater currently are pump and treat (P&T) and filtering in place, referred to as in situ, using colloidal activated carbon (CAC). Both approaches use carbon filtration to remove contaminants from groundwater. The choice between below-ground in situ and above-ground P&T filtration becomes critical when considering potential future exposure risk and environmental impacts.
Pump & Treat: Expensive and Ineffective for Groundwater Remediation”
P&T is a hydraulic containment approach that requires stopping groundwater movement to contain a PFAS plume, which describes how the chemicals disperse in groundwater near a contamination site.
A typical P&T system requires annually pumping millions of gallons of water to the surface to be filtered through vessels or filter beds containing granular activated carbon (GAC) or other filter media.
The energy required just for pumping water is an underappreciated energy hog, resulting in extraordinary costs levied onto taxpayers and the environment. A typical P&T system to contain a PFAS plume in groundwater consumes 64,000 kilowatt-hours of energy and produces more than 500,000 pounds of CO 2 emissions annually. In attempting to “treat” groundwater, P&T sacrifices our Earth’s atmosphere.
Generating and disposing of tons of PFAS-soaked filter media leads to other problems. Each P&T system generates large amounts of PFAS-soaked filter materials that must be trucked to a landfill, potentially re-contaminating the environment via spills during transport. PFAS may also leach into groundwater following disposal in a landfill. By moving PFAS-contamination above ground and transferring to a new location, P&T redistributes the contaminants, opening new exposure pathways. Additionally, the U.S. Environmental Protection Agency has not currently identified a safe method for incinerating PFAS waste materials.
Because P&T is an energy-intensive, polluting approach, it was deemed “expensive and ineffective for groundwater remediation” by the U.S. Government Accountability Office in 2005. Congress concluded the process is “costly and inefficient” in the National Defense Authorization Act Appropriation bill currently under consideration.
In Situ Remediation: A Highly Effective, Low-Cost and Sustainable Alternative
Remediating PFAS in situ uses activated carbon to transform the groundwater aquifer into a massive underground filter to immobilize PFAS.
My company makes PlumeStop, a form of CAC that uses blood-cell-sized carbon particles sourced from coconuts which are suspended in a food-safe solution to create a liquid, colloidal form of activated carbon. Ink-like in appearance, the patented novel carbon form is non-clumping, allowing it to slip through the soil or rock pores. The subsurface is “painted”with highly reactive carbon in the process, forming an expansive subterranean filter surface covering 100 acres for every pound of CAC injected.
CAC is injected into the ground to create one or more filtrdation zones or permeable barriers placed between a PFAS source and a receptor such as a water well or stream to remove PFAS from groundwater. The process captures PFAS in a vast underground filter that blocks the further spread of forever chemicals in the aquifer.
Because in situ filtration occurs below ground, it avoids the energy-intensive practice of pumping water, which offset tons of GHG emissions annually per P&T system replacement. A recently published study shows in situ CAC treatment reduces GHG emissions by 98% compared to P&T methods. These treatments also avoid pumping contaminants above the surface and generating toxic waste products that must be managed, transported, and disposed of.
Since PFAS concentrations in groundwater are typically minuscule — often measured in the parts-per-trillion range — and the filter surface immense, in situ CAC treatments can be designed as a permanent solution to eliminate PFAS exposure risk, forever holding the contaminants in place where they cannot harm.
More than 40 PFAS-contaminated groundwater sites have been treated using the in situ CAC approach thus far, supported by peer-reviewed studies demonstrating its long-term effectiveness. As more sites are identified for remediation in the coming years, this paradigm-shifting strategy to contain PFAS and prevent exposure risk can potentially save billions of dollars and eliminate millions of tons of GHG emissions, meeting the need for environmental stewardship in addressing the PFAS crisis.
An Appeal for Your Help
It will take time before this naturally powered solution for protecting our drinking water is fully adopted, and your help is needed to make it happen. Now that you are aware of this important issue, please share your knowledge by passing this article on to your family, friends, and neighbors. Tell your representatives that there are more sustainable and effective approaches to PFAS remediation.
If you or someone you know lives near a military base, airport, landfill, fire training academy or other potential PFAS source, and relies on a well for water supply, ensure that the water is tested for PFAS. The National Groundwater Association provides an informative fact sheet offering guidance on PFAS testing and treatment, if necessary, for private well owners.
About the Author
Ryan Moore is the PFAS Program Manager at REGENESIS.