PFAS Remediation

How To Construct A Temporary Solution For A Forever Chemical

Per-and polyfluoroalkyl substances (PFAS) are known as forever chemicals due to their incredible level of stability. Testing has identified more than 2,500 PFAS-contaminated water sources and more are being discovered with each passing year.

Water treatment plants (WTPs) and wastewater treatment plants (WWTPs) all over the Europe continue to grapple with methods and technologies for treating and removing PFAS from drinking water. As rules and regulations regarding PFAS evolve and expand, PFAS contamination is now impacting a wide range of operations and organizations, including those whose expertise is not in water treatment, let alone PFAS removal.

Despite being known as a forever chemical, not all situations require a permanent treatment installation. For example, underground infrastructure installation and repairs may require a dewatering process. If this water is found to have PFAS (or other contaminants), a temporary treatment solution can help remove the chemicals to meet regulatory requirements.

What Is PFAS And How Is It Treated?

PFAS were developed in the 1940s for applications where resisting or repelling grease and/or moisture is important. Today this family of chemicals can be found in wide range of products, from food wrappers to weather-resistant clothing. It is also used in firefighting applications, particularly where grease fires may be common.

The chemicals’ unique molecular stability means that they are extraordinarily difficult to break down into less hazardous chemicals. They burn only at temperatures greater than 1,000°C. Therefore, the only way to reduce their presence in water is through physical media filtration.

Ion exchange (IX) resins, granular activated carbon (GAC), and membrane systems such as nanofiltration reverse osmosis (RO) are all effective at removing PFAS (Figure 1). The exact remediation solution will depend on a variety of factors, including the water chemistry, presence of other contaminants, budget, volume and flow rate of water to be treated, and more.

Figure 1. Physical media filters, including granular activated carbon (top) and ion exchange (IX) resins, are highly effective solutions for removing per- and polyfluoroalkyl substances (PFAS)from water.

What You Need To Know About PFAS

Before attempting to execute a solution to PFAS contamination, it is critical to understand a few key things:

Removing PFAS is doable.

While there are no federal regulations on PFAS in drinking water, many states are imposing aggressive maximum contaminant levels (MCLs) on discharged water, requiring concentrations in parts per trillion (ppt). This may seem challenging, particularly to those who are not experts in water treatment. However, it is very achievable with the right technologies and system design. Because water resistance is one of the desired properties of PFAS for industrial and commercial use, it is far less water soluble than other challenging contaminants (such as 1,4-dioxane). Thus, it can be adsorbed or filtered under the right circumstances.

Other contaminants must be addressed first.

One of the keys to successfully removing PFAS from any water stream is to remove as many other contaminants as possible before addressing PFAS. Because physical media filtration or adsorption are the most effective solutions, it is critical to ensure that the media bandwidth is not used on contaminants that can be more effectively removed in other ways.

Figure 2. Effective remediation of PFAS often requires removing other contaminants upfront and then adding a dedicated media filter such as IX resin at the end of the treatment train. The example above uses a clarifier and sand filters to remove TSS and reduce turbidity and a carbon media filter to remove hydrocarbons. A pair of IX resin vessels are included to remove PFAS before discharge.

For example, water with high levels of natural organic carbon or total suspended solids (TSS) may require a sand filter, clarifier, or other treatment process(es) to remove this material before the stream passes through an IX filter to address PFAS (Figure 2). Addressing PFAS last in the treatment train not only increases removal rates, it also reduces filter changeouts and saves money in the long run.

How To Choose A Temporary PFAS Treatment Solution

There are a lot of options for temporary PFAS remediation. Before implementation, it is critical to ensure the following:

The technology is easy to use. Since many temporary solutions are expected to be used by professionals outside the water treatment industry, they must be easy for anyone to learn to use.
The solution must be customizable. Removing PFAS is not a one-size-fits-all process. The right solution depends on a number of factors, including water chemistry and other contaminants that maybe present, as well as local or state regulations. All of these things may impact the type of solution needed.
The solution must be designed by experts. At present, there are very few experts in PFAS remediation in the U.S. and abroad. Still, it is important to have a solution that is designed by those who understand the challenges and intricacies of the chemical and associated treatment technologies.
The solution provider must offer technical support. In addition to offering experts to help design the solution, the right vendor should be able to provide knowledgeable technical support should unexpected challenges arise.
Equipment must be readily available. With supply chain delays wreaking havoc in nearly every industry, it is essential that any solution be readily available to avoid project delays and associated costs.