PFAS Pilot Treatment Systems: Everything you need to know

Why is it important to conduct a PFAS pilot when choosing a mitigation system?

With the burden of PFAS removal from drinking water now squarely placed on the shoulders of water treatment plants, utilities are scrambling to put treatment systems in place. The clock is ticking down to June 2029, when public water treatment plants must achieve PFAS levels of no higher than 4 parts per trillion for two common PFAS (PFOA and PFOS) and 10 parts per trillion for 3 others (PFHxS, PFNA and HFPO-DA). In addition, PFAS mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA and PFBS are regulated using a Hazard Index MCL to account for the combined levels of these PFAS in drinking water.

Under such a time constraint, plant operators may believe that they don’t have enough time to conduct a PFAS pilot, but this is not the case. Given the significant investment of new treatment technology, it’s critical that plants make the right decisions to avoid finding themselves with expensive equipment that cannot achieve compliance or costs more to treat the water than it should. As the industry continues to learn more about how to treat PFAS with widely varying water sources , a PFAS pilot study is the only way to design a system that is affordable, meets the specific needs of the plant and can achieve compliance by the June 2029 deadline. Through piloting, plants can optimize a system and reduce total cost of ownership.

How can a PFAS pilot reduce total cost of ownership?

Essentially, piloting reduces much of the financial risk associated with installing a new treatment system in four main ways.

First, a pilot keeps a close eye on water quality and can report on contaminants and chemical makeup that the plant wasn’t aware of. With longer pilots, unknown and “slow to appear” problems will reveal themselves, presenting an opportunity for the design team to ensure that the full-scale system will treat those problems. In the context of short-chain vs long-chain PFAS removal, this aspect is especially relevant because not all technologies can remove both kinds equally well.

Second, a pilot gives operational staff a chance to interact with the technology to discern if it’s a match for their protocol, space constraints and other unique site and staff characteristics.

Third, a pilot provides an accurate forecast of how often media will need to be changed out. This budget item is a major element of the total cost of ownership and can only be fully understood by subjecting the media to local conditions over a stretch of time.

Finally, a pilot provides a special low-risk opportunity for a plant to test something new. Innovations in water treatment are at an all-time high, and through piloting, facilities may discover a superior product that performs well and reduces costs.

If any of these decisions are rushed and made without a pilot, it can end up costing the plant millions of dollars over the life of the equipment.

How long should a PFAS pilot run?

When time is of the essence, a pilot of three to six months can provide some data. However, learnings from a short pilot will need to be extrapolated and are likely to miss key insights. Ideally a pilot should last 12 to 18 months, which is usually long enough to completely exhaust the initial media and capture a full year of changes to the water, minimizing the chance of surprise contamination spikes (such as those that happen seasonally or irregularly because of extreme weather or occasional nearby industrial activity). One key learning is a plant’s exposure to specific PFAS compounds, because there are differences in approaching short-chain vs. long-chain PFAS removal.

As the water treatment industry learns more about how to treat PFAS, investing in a pilot program early is key to success.

What is a water profile?

A PFAS pilot usually starts with a complete water profile that includes a water analysis, contaminant targeting, evaluation of other technologies already on site that may be used for pretreatment, assessment of space limitations and calculations of the volume of water needing treatment now and into the foreseeable future. This profile reveals valuable data points that will help make the best decisions at every turn.

Another consideration during the water profile stage is the discovery of unregulated PFAS in sample water. If the first PFAS to be detected are unregulated ones, customers will need to decide how they want to proceed: worry only about the regulated PFAS, or treat them all to get ahead of future regulations.

It should be noted that a one-time water analysis is only a snapshot and does not capture changes in water over a year. Facility operators are advised to mention known changes due to seasonality and other recent observations in extreme weather to achieve a total understanding of the challenges presented by a plant’s specific water. Continuing to analyze water quality throughout the pilot is a best practice that can draw the most accurate picture of a facility’s needs as they related to contaminants.

How to treat PFAS: Remediation media often tested during piloting

The current most common solutions for PFAS removal are granular activated carbon (GAC) and ion exchange (IX) resin.

Granular Activated Carbon (GAC) is a long-proven technology for contaminant removal, with strong market acceptance and a low operating cost. Able to reduce PFAS to non-detectable levels, GAC works best with long-chain PFAS. Compared to IX, it is better able to remove additional organic contaminants and disinfection by-products. At 10-20 minutes, its empty bed contact time (EBCT) is longer than IX and the filtration rate (linear velocity) is lower, which means the equipment will have a larger footprint and taller tanks than IX, which increases initial capital expenses.

Ion Exchange (IX) uses anionic resin media that specifically targets PFAS, as IX is negatively charged to attract the positively charged “head” of the PFAS compounds. It offers better removal of both short- and long-chain PFAS than GAC and can reduce PFAS to non-detectable levels (as much as 99.99% removal) using a very short (2-3 minutes) EBCT, allowing for a smaller installation and a reduced capital expense. This single-use media offers the longest life of its kind on the market.

With both IX and GAC, spent media must be removed and sent off-site for thermal destruction, which at present is the most common option for destroying PFAS.

Can vessel designs be tested during a PFAS pilot?

Vessel designs are an important part of treatment, especially as they relate to how much media utilization can be achieved. New innovations in vessel design are offering higher media utilization without sacrificing ease of media and tank inspection.

While it is difficult to demonstrate full-scale hydraulics that can be influenced by inlet and underdrain designs in the pressure vessels used to house the media, it is important to understand how the supplier designs their full-scale equipment so that whatever media that is chosen is used efficiently and without short-circuiting, which wastes media life and increases costs.

Why work with De Nora?

For more than 25 years, De Nora has pioneered water contamination removal products with its SORB Contaminant Removal Solutions, developing expertise that has provided a firm foundation for the company’s PFAS mitigation systems and showing customers how to remove PFAS from water.

Helping utilities remove PFAS from the water supply while minimizing capital and operating expenses has become a focus of research and development at De Nora. Through ongoing innovations, De Nora is setting the standard for the future of water treatment, allowing utilities to promise safety in water and the environment while getting the most out of their financial resources.

De Nora partners with clients to meet their most pressing needs, having contributed to tens of thousands of installations globally over decades of experience and particular expertise in traditional and emerging contaminants of concern such as PFAS, 1,4-dioxane, micropollutants and DBPs.

De Nora’s unique vessel design saves water treatment facilities capital expenses in the form of lower installation and initial media costs, and operating expenses in the form of a reduced maintenance burden, optimized media utilization which extends media life and requires less frequent downtime.

As regulation around PFAS removal intensifies on the federal level, De Nora is committed to allying with treatment facilities to help them meet the growing demands on their industry.