Onsite PFAS Destruction: Understanding Electrochemical Oxidation

Author: Louis LeBrun, PE, VP of Sales, Axine Water Technologies

As the need for PFAS treatment continues to emerge, landfills and waste management facilities can rely on electrochemical oxidation as a proven option for the complete destruction of PFAS and other contaminants.

Issues concerning the presence and fate of per and poly-fluoroalkyl substances (PFAS) in the environment have taken center stage for landfills and other waste management facilities over the past several years. While final rules around these "forever chemicals" have yet to be issued by the EPA, many states have taken a proactive approach towards the regulation and monitoring of PFAS. As a result, waste management facilities are actively seeking solutions to address the issue as final regulations rapidly come into view.

To date, many facilities looking to treat PFAS from liquid waste, such as leachate, have turned to some form of capture or concentration technology, such as foam fractionation, ion exchange (IX), reverse osmosis (RO), or granular activated carbon (GAC). While efficient, these technologies are simply means of abstraction, leaving behind spent media or concentrated liquid waste that requires disposal—sometimes within the same solid waste facilities seeking solutions to the issue. Fortunately, more complete solutions are now available to destroy PFAS, eliminating the problem entirely.

Electrochemical Oxidation

Among the most promising solutions for the destruction of PFAS is the newest iteration of electrochemical oxidation (EOx) technologies. EOx is an extremely powerful form of advanced oxidation processes (AOPs), which has been in use for water and wastewater treatment for decades. Electrochemical oxidation uses the power of electrical energy to chemically destroy even the most difficult-to-treat compounds. Fundamentally, electrochemical oxidation involves submerging a pair of conductive electrode elements into a process stream and then applying a relatively low electrical current. Once energized, electrons leaving the anode (negative conductor) initiate a chain of oxidation reactions that affect treatment.

One of the main advantages of electrochemical oxidation is its ability to destroy even the most challenging compounds, including PFAS, complex organics, or pharmaceutical agents. Such compounds typically react at the anode surface, where an electron can directly break chemical bonds or create smaller molecules that are more available for further reaction. Simultaneously, electrons react with water to form powerful chemical radicals and mixed oxidants, further perpetuating treatment. Through this process, contaminants are sequentially broken down through successive direct and indirect reactions until no further reactions are possible. Simple and well-proven process controls, such as pH control and off-gas collection, ensure that no harmful by-products or conditions result during treatment.

By far, the most important advantage of electrochemical oxidation is its ability to destroy contaminants all the way back to their elemental building blocks, such as carbon, oxygen, hydrogen, and other mineral salts. This eliminates waste from the treatment process, ensures compliance with strict regulations, and reduces long-term risks to both customers and the environment.

Important Advantages

The choice of electrode materials plays a huge role in the effectiveness of any electrochemical oxidation process, and a wide range of materials are available for use. The most effective results are achieved by carefully mixing and matching a range of electrode materials for each application. This allows the process designer to achieve the highest reactivity while minimizing energy use and long-term operating costs. As a result, electrochemical oxidation systems using a mixed-electrode approach often deliver the most efficient and cost-effective results.

Process controls are also important in any form of electrochemical oxidation treatment. Continuous monitoring of influent quality, electrical energy use, and other water quality parameters is essential to achieve effective treatment. More importantly, because energy demand can vary throughout the electrochemical destruction process, careful energy monitoring helps maximize both process efficiency and electrode life. To effectively achieve these goals, the most advanced electrochemical systems currently available use artificial intelligence (AI) and machine learning (ML) to continually monitor and optimize the treatment process in real time.

Electrochemical oxidation systems have other advantages over thermal oxidation, incineration, and supercritical water oxidation (SCWO) options that might also be considered for PFAS destruction. Unlike thermal and SCWO, electrochemical oxidation systems operate at ambient temperature and pressure, eliminating the most common safety concerns associated with thermal processes. Electrochemical systems can also accept a wide range of water qualities, such as high total dissolved solids (TDS) or high volatile organic compounds (VOCs), which are common from ion-exchange, foam fractionation, and other upstream treatment processes, making EOx an ideal choice for a wide range of facilities.

Testing Process

Customers selecting a PFAS treatment option are reassured by the simple testing process and proven track record of EOx treatment. Laboratory bench testing can be conducted with as little as a 5-gallon (20L) sample to identify the best combination of electrode materials and overall treatment prognosis. Follow up onsite pilot testing is also easy to achieve using small-scale mobile treatment systems to optimize treatment conditions and operating costs. Both types of treatment programs should be available to help guide the evaluation, selection, and design process to demonstrate treatment results.

Experience is also an important consideration in solution selection. The most advanced electrochemical treatment processes can demonstrate many years of successful full-scale results. It is for this reason that many of the world's largest pharmaceutical manufacturers and other industries have relied on electrochemical oxidation for their most mission-critical waste treatment applications. Customers seeking solutions for PFAS need only look to previous full-scale results and industrial facilities to be assured of their choice in both technology and provider.

Finally, electrochemical oxidation treatment systems are easy to implement at most customer sites. The best EOx technologies are available as turnkey treatment solutions with guaranteed results. Such "Treatment-as-a-Service" (TaaS) solutions are easy to implement since they eliminate the customer's need for large initial capital outlays and dedicated staff to operate and maintain the system. As a result, customers can maintain focus on their core business with the assurance of knowing that regulatory limits are consistently being achieved.

A Proven Solution

As the need for PFAS treatment continues to emerge, landfills and waste management facilities can rely on electrochemical oxidation as a proven option for the complete destruction of PFAS and other contaminants. Electrochemical systems are simple, safe, and cost-effective to implement while guaranteeing compliance with even the strictest regulations. This new family of technology eliminates concerns about the fate of PFAS, both today and into the future.

About the Author

Louis LeBrun, PE, is a professional engineer with more than 25 years of experience in water and wastewater treatment, including advanced oxidation and electrochemical oxidation processes. During this time, he has been involved in delivering treatment solutions and commercializing treatment technologies throughout North America, South America, Europe, and Asia. In his current role as Vice President of Sales at Axine Water Technologies, he is responsible for the delivery of treatment solutions worldwide. Connect with Louis on LinkedIn, via email at llebrun@axinewater.com,or by phone at (919) 996-9372.

Look out for our upcoming article on electrochemical PFAS destruction, which is also included in this series. The article discusses important aspect of how PFAS is sequentially broken down in the electrochemical process using data and examples from actual onsite results. For more information about Axine Water Technologies’ electraCLEAR^® electrochemical oxidation process, call (604) 336-8900 or visit www.axinewater.com.