PFAS Remediation

WHAT IS PFAS?

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that include PFOA, PFOS, GenX, and many other chemicals. The U.S. EPA has established health advisories for PFOA and PFOS in drinking water and has established the health advisory levels at 70 parts per trillion. Both PFOA and PFOS have been detected in water, wildlife, and humans worldwide, according to the US EPA.

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HOW ARE PFAS CHEMICALS USED?

PFAS chemicals have been used in a variety of consumer products over the last several decades. Applications of these chemicals include non-stick cooking surfaces, fabric, and carpet stain-resistant sprays and treatments, water-repellent sprays and treatments, non-stick consumer food packaging, and other protective coatings. They were, and in some cases still are, used in specialized fire-fighting foams for use at airfields and other civil and industrial sites that have a high risk for petroleum-based fire.

ENVIRONMENTAL PERSISTENCE OF PFAS

PFOA and PFOS were phased out of production in the United States by 2010 through a combination of voluntary phaseout and the EPA’s PFOA Stewardship Program which also encouraged manufacturers to stop using these chemicals in products by 2015. However, PFOA and PFOS are environmentally persistent: they do not break down when exposed to air, water, or sunlight. As a result, humans and wildlife may be exposed to PFAS chemicals manufactured many years in the past.

PFOA AND PFOS IN
DRINKING WATER

Apart from exposure to consumer products that contain PFOA and PFAS, some fire-fighting foams used to combat aviation fires release PFOA to the environment, putting surface and ground water resources in close proximity to civil airports, military airbases, and other areas where these foams have been used at risk of contamination. Because these chemicals are environmentally persistent, it is possible for surface and groundwater contamination to penetrate into municipal water supplies and private wells.

ADDITIONAL PFAS CONTAMINANTS OF CONCERN

In 2022, EPA updated its list of PFAS compounds to include five different contaminants. The five PFAS compounds now include: hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA – sometimes referred to as GenX chemicals), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS).

PFAS REMEDIATION

Currently, there are three basic technologies for removing PFAS from water:

1. GRANULATED ACTIVATED CARBON

The most common treatment approach, particularly for impacted drinking water supplies, is granular activated carbon, which can (under ideal conditions) provide consistent removal to part per trillion (ppt) levels required to meet individual state drinking water requirements. GWTT has found that longer empty bed contact times (EBCTs) are required as compared to typical volatile organic compounds (VOCs) and hydrocarbons.

In addition, breakthrough is typically observed earlier as compared to other typical contaminants for which carbon is utilized. One advantage of activated carbon is that it can oftentimes be recycled by the carbon supplier via a steam reactivation process. Based on current regulations, the carbon can be handled as a non-hazardous waste. Therefore, although carbon consumption and costs can be high, disposal costs are manageable.

2. NON-REGENERATING SYNTHETIC RESINS

Synthetic resins are now being used in some cases where manufacturers can meet stringent treatment requirements and extend treatment duration over carbon. Combinations of carbon followed by a resin product are often suggested for PFAS remediation, with carbon being used as a primary technology and the resin being used as a polishing bed. This can extend carbon usage and limit overall consumption while extending PPT treatment objectives. One disadvantage is that the synthetic resin, once exhausted, requires disposal.

3. REGENERATING SYNTHETIC RESINS

A recent treatment development for PFAS remediation is a synthetic resin that can be regenerated on-site. However, this type of installation is comparatively expensive since regeneration equipment must be installed as part of treatment plant capital investment. Long-term operations using this technology have not yet been demonstrated, so it is difficult to determine if this technology represents a cost-beneficial method for fixed treatment plants as compared to carbon or single-life resins. However, as this technology is deployed at PFOS sites and further refined, its efficacy will be determined.

ONE SIZE DOES NOT FIT ALL

GWTT has utilized these treatment technologies at various sites for various customers. What we have learned through experience is that each project site has a unique contaminant profile, and there is no one-size-fits-all solution. Our approach to successful treatment is to perform a battery of water and soil testing to gain a deep understanding of the contaminants. Then we will develop a treatment system that addresses the unique challenges of that particular site or project.

LET GWTT HELP SOLVE YOUR PFAS REMEDIATION CHALLENGES

Through a combination of our systems engineering and chemistry expertise, GWTT will build and operate a treatment system that utilizes a combination of technologies to meet the specific contaminant profile and effluent requirements of your project. We have demonstrated project experience treating PFOA- and PFOS-contaminated water and will leverage that expertise to develop a customized turnkey solution for your PFAS remediation challenges.

As a vertically integrated environmental remediation company, GWTT can self-perform civil, electrical, and mechanical site work; equipment fabrication and customization; dewatering; and licensed operation and maintenance of soil, air, and groundwater treatment systems.

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