Kidney cancer, low birth weights, and reduced vaccine effectiveness. Per-and polyfluoroalkyl substances (PFAS) are hazardous substances that harm ecosystems and can have severe effects on human health, compounded by their persistent nature and environmental accumulation.
To further complicate things, each remediation project is unique and several PFAS treatment and destruction solutions are available. By taking the time to understand all the factors influencing treatment effectiveness, markets such as airports, industrial, defense, and solid waste can find strategic technology pairings that remove and destroy PFAS while managing input costs, energy use, and the amount of waste produced.
The Value of Treatability Studies
Treatability studies are relatively inexpensive analyses that help organizations understand their source water characteristics before they invest in full-scale treatment solutions. They walk through:
- Pre-Treatment Requirements
- Cost Comparisons of Technologies
- Media Piloting and Demonstration of PFAS Destruction
- Process Optimization
The insights gained from treatability studies can have a significant return on investment by confirming and optimizing treatment train performance, demystifying the cost of ownership, and providing proof of concept.
New Avenues for PFAS Separation
There is a range of options to destroy and remove PFAS. However, treatability study results should guide technological selection. A holistic PFAS treatment train may comprise various treatment methods such as Granular Activated Carbon (GAC), single-use ion exchange resin (IEX), foam fractionation (FF), and regenerable IEX resin. While GAC and single-use IEX can apply to certain situations, they are not single-size-fits-all. To improve the total cost of ownership, footprint, waste volumes generated, and sustainability initiatives, ECT2 has innovated and developed other technologies that target PFAS. Regenerable IEX resin and foam fractionation are two technologies that can improve remediation outcomes.
Regenerable Resin and Foam Fractionation: Powerful Technologies for Consideration
Regenerable IEX resin relies on the same principles as single-use IEX resin, except that spent media beds can be regenerated and used in subsequent treatment instead of discarding single-use resin and purchasing new media.
Regenerable IEX resins rely on a regeneration unit to remove PFAS from exhausted media. Eliminating the cost of replacement media offsets the additional capital cost of this equipment. To further offset the cost of regeneration technology, a hub-and-spoke approach should be considered where one regeneration hub can serve multiple treatment sites nearby. The more often resin requires change-out, the more economically advantageous the regenerable resin technology becomes. Regenerable IEX resin is also “future-proof”, meaning the technology can handle lower treatment objectives and/or short chain removal requirements.
Foam fractionation efficiently and effectively removes PFAS from water while being agnostic to co-contaminants like dissolved organics, metals, and salts. It works by introducing air into the bottom of the fractionator in a countercurrent flow to the influent, promoting the migration of PFAS into air bubbles. These bubbles float to the top of the reactor in a foam layer to be collected by vacuum. Putting multiple reactors in series or extending the residence time in the reactor can further improve removal efficiency. The lack of pre-treatment requirements makes foam fractionation well-suited for difficult matrices like landfill leachate, industrial wastewaters, or AFFF-impacted ponds with high organics.
Foam fractionation is good at removing long-chain PFAS and doesn’t require much energy while avoiding the need for a lot of pre-treatment. However, the technology struggles with removing short-chain PFAS with high efficiency. Regenerable IEX resin, on the other hand, is good at short-chain PFAS removal and is a more sustainable approach to PFAS treatment due to the reduced waste volumes generated. The drawback is the additional capital costs for the regeneration technology.
Both foam fractionation and regenerable IEX resin technologies are a bridge to destructive technologies. To make destruction technologies more economically viable, a PFAS concentration step must be performed. This reduces the overall volume requiring destructive treatment.
Separate, Concentrate, Destroy
After separation and concentration, a destruction step can be incorporated. Several PFAS destruction technologies are available, each with different approaches, costs, and throughput. Drawbacks to the technologies do exist: some struggle with short-chain compound destruction, by-product formation, or handling high salt concentrations. Additionally, the technologies are at different levels of technical maturity. All technologies are advancing rapidly, though, as research continues. Destructive technologies can be categorized as:
- Electrochemical Oxidation
- Non-Thermal Plasma
- UV Photosensitized Reduction
- Hydrothermal Alkaline Treatment (HALT)
- Supercritical Water Oxidation (SCWO)
The first three processes operate at ambient temperature and pressure, while HALT and SCWO use elevated temperature and pressure. At ECT2, we’ve worked with eight different destruction vendors and understand some of the challenges associated with each technology. Fully characterizing the waste matrix undergoing treatment is key, like in the separation and concentration steps.
In one project, historical fire-fighting activities created a PFAS-impacted pond that required treatment. In addition to PFAS, the matrix undergoing treatment included fuel co-contaminants and high iron concentrations. To handle this complex water, ECT2 partnered with Aquagga’s HALT system to separate, concentrate, and destroy PFAS. Over two weeks, the foam fractionation and HALT combination treated 20,000 gallons of AFFF-impacted water, removing more than 99.9% of targeted PFAS chemicals from the fire-training pit water. The collected foamate consisted of concentrated PFAS (10-50 mg/L) that was transferred to the HALT system for destruction. Approximately 1,300 gallons of concentrated PFAS liquid were produced and destroyed, meeting project treatment goals.
Final Thoughts
PFAS is a complex issue. Each site’s unique characteristics and challenges determine the solutions that can be used, and no one solution is right for every project. With considerations from an initial treatability study, organizations can determine which pre-treatment, separation, and concentration steps, as well as destruction technologies more effectively address their requirements. Solutions like regenerable IEX resin and foam fractionation are two technologies that remove PFAS from impacted water and act as a bridge to a destructive technology.
Equipped with experience, know-how, and technology, ECT2 can assist in effectively meeting treatment objectives while ensuring the safety and health of the environment. If recent PFAS regulations are impacting your facility, start the conversation today with our team by filling out this form. One of our experienced team members will be in touch with you soon!
