To a wastewater treatment engineer, at least during workdays, it seems like everyone is talking about forever chemicals, all of the time. There’s a good reason for that, because the huge group of man-made chemicals has climbed in priority to be at the top of most wastewater treatment regulatory considerations. Forever chemicals are also known as per and polyfluoroalkyl substances (PFAS) and have rapidly become the latest of the emerging contaminants in drinking water to be treated. So, while there is still a lot of toxicology research to do, PFAS destruction and even which PFAS actually needs to be addressed, there is very little doubt regarding the future need to treat PFAS in landfill leachate and other wastewaters. Everyone is in agreement, the environment needs to be protected from forever chemicals.
PFAS chemicals can withstand high heat without becoming unstable as well as repelling oil and water, making them ideal for inclusion in fire-fighting foam, lining non-stick pans, or water resistant clothing. But unfortunately, PFAS can persist in the environment – water, fish, humans, etc. – for a long time. So, having efficient and cost-effective methods of treating wastewater, drinking water, bio-solids, etc., to reduce/remove PFAS is becoming increasingly important. Luckily, some traditional and very available treatment methods are effective at treating PFAS as well as some newer, non-traditional treatment methods that appear to be promising.
One effective management technology is using deep injection wells to store the PFAS contaminated wastewater deep, far below drinking water sources and within high total dissolved solids groundwater. Deep injection wells are only allowed where the deep geology and subsurface conditions can allow for the PFAS wastewater to be contained where it is injected.
Additional management options are granular activated carbon (GAC) or ion exchange (IX), which are adsorption treatment methods that use a media, through which the PFAS contaminated wastewater can pass, and the charged PFAS molecules become bound up in the opposite charged GAC or IX media.
Reverse osmosis (RO) and foam fractionation (FF) treatment methods use separation, either through very small pores in a membrane (RO) or applying aeration to create a PFAS concentrated foam (FF), to allow the treated, cleaner water to discharge the treatment process and the concentrate (RO) or foamate (FF) is left and can be dealt with more efficiently, because after treatment the concentrate/foamate is a much smaller volume than the original wastewater flow.
These PFAS management methods simply move the PFAS chemicals out of the way and don’t actually destroy the PFAS. PFAS destruction generally requires more effort and cost because high pressure and/or high heat are required to break the carbon – fluorine (C-F) bonds. A regenerative thermal oxidizer (RTO) or supercritical water oxidation (SCWO) are PFAS destruction methods that can be employed. An RTO typically operates at high temperature (e.g., 1,800 F) and SCWO utilizes both high temperature (>705 F) and high pressure (>3,210 psi) within a process to, again, break the C-F bonds. Electrocoagulation, advanced oxidation processes and plasma are also treatment methods that could be employed to destroy PFAS.
These are just a few of the many PFAS management and destruction options. It can be hard to decide what’s right for your project. That’s where SCS can help. We’re technology agnostic – so you can trust our recommendations are appropriate for your project and goals. Contact us today to learn more about what’s possible.
About the Author: Sam Cooke, PE, CEM, MBA, is a Vice President and our expert on Industrial Wastewater Pretreatment. He has nearly three decades of professional and project management experience in engineering with a concentration in environmental and energy engineering. Mr. Cooke works within SCS’s Liquids Management initiative to provide services to our clients nationwide.
Additional PFAS Management and Treatment Resources:
In this Waste Today article, Sam Cooke discusses the factors, treatment options, analytical methods, and identifying PFAS sources to most effectively reduce the concentrations of ammonia and PFAS in landfill leachate.
Reducing these concentrations help meet discharge permit requirements for direct discharge of treated leachate to surface waters and to meet publicly owned treatment works (POTW) discharge permit standards.
Sam points out that accomplishing ammonia and PFAS reduction with established wastewater treatment technologies works, but the right treatment depends on each site’s specific parameters. He suggests conducting bench-scale and pilot-scale testing for any feasible nitrogen removal or treatment system. Testing the wastewater helps to identify any changes in the concentration of nitrogen compounds. Thus, necessary changes to the treatment processes, such as additional aeration or chemical additions are easier to identify and less costly to implement.
About the Author: Mr. Cooke, PE, CEM, MBA, is a Vice President and our expert on Industrial Waste Pretreatment. He has nearly three decades of professional and project management experience in engineering with a concentration in environmental and energy engineering. Mr. Cooke works within SCS’s Liquids Management initiative to provide services to our clients nationwide.