Grantee Research Project Results
Final Report: Hydrothermal Treatment of PFAS-Contaminated Groundwater
EPA Contract Number: 68HERC22C0038Title: Hydrothermal Treatment of PFAS-Contaminated Groundwater
Investigators: Pinkard, Brian
Small Business: Aquagga Inc.
EPA Contact: Richards, April
Phase: II
Project Period: January 1, 2022 through December 31, 2023 (Extended to December 31, 2024)
RFA: Small Business Innovation Research (SBIR) Phase II (2022) Recipients Lists
Research Category: Heavy Metal Contamination of Soil/Water , SBIR - Land Revitalization , Small Business Innovation Research (SBIR) , Urban Air Toxics
Description:
The management and treatment of per- and polyfluoroalkyl substance (PFAS) contaminated groundwater is a major challenge within the environmental remediation industry. PFAS are recalcitrant environmental pollutants which mostly do not degrade under natural conditions. PFAS are extremely bioaccumulative, leading to toxicity concerns even at very low (part-per-trillion [ppt]) levels. New treatment technologies are needed to remove PFAS from environmental matrices, and to destroy PFAS in concentrated environmental remediation and wastewater treatment byproducts.
In this EPA SBIR Phase II project, entitled Hydrothermal Treatment of PFAS-Contaminated Groundwater, the Aquagga, Inc. (Aquagga) project team designed, prototyped, fabricated, and tested a commercial-scale, technology readiness level (TRL) 6 continuous flow hydrothermal alkaline treatment (HALT) reactor capable of destroying PFAS in concentrated liquid feedstocks. The purpose of the project was to scale up the HALT technology from the prior system maximum throughputs of 1 gallon per hour (gph) to a target maximum throughput of 10 gph. This scaled-up design required a larger reactor vessel, improved heating and cooling strategies, fully integrated PLC control, and more thorough component integration. The conducted R&D efforts were primarily focused on completing a fully engineered design of the TRL 6 system, along with fabricating and testing the system within Aquagga's testbed facilities in Tacoma, WA. Ultimately, the system was tested processing trifluoromethanesulfonic acid (TFMS), a surrogate PFAS compound which is known to be difficult to destroy. Electricity and chemical consumption was measured and TFMS destruction was measured at several operating conditions, to determine the system efficacy and estimates of operating requirements.
Summary/Accomplishments (Outputs/Outcomes):
The TRL 6 reactor was successfully designed and fabricated by the Aquagga team within the project schedule and budget. The finalized system was evaluated by performing PFAS destruction tests with TFMS as a model PFAS compound, as previous testing has indicated that TFMS is the PFAS compound most resistant to degradation under HALT conditions. Testing revealed that >99% destruction and removal efficiency was achieved with a TFMS feedstock, confirming successful reactor performance. Variations in TFMS destruction were measured with two different sodium hydroxide (NaOH) loadings used, showing that NaOH concentration significantly impacts destruction efficacy. Changes in reactor throughput also impacted the extent of TFMS destruction, as residence times and maximum temperature were both altered. Energy and chemical consumption metrics were captured, allowing for estimates of system CapEx and OpEx costs based on the measured costs of system fabrication and operation.
Conclusions:
HALT appears to be commercially and technically viable for the destruction of PFAS in liquid concentrates, particularly in complex matrices. TFMS, one of the most recalcitrant and difficult to destroy PFAS compounds, is successfully destroyed with HALT, requiring less than 1 kWh/gallon. Additionally, HALT is easy to automate and operate, which could lead to a safe and reliable commercial PFAS destruction offering for the environmental remediation industry.
The Aquagga team has identified myriad commercial opportunities for PFAS destruction using the HALT technology. Primarily, these opportunities involve coupling HALT with a suitable PFAS separation and concentration technology, such as foam fractionation (FF) or regenerable ion exchange resins (IXR). HALT is exceptional for treating PFAS-rich wastewaters with high TDS, high TOC, high chloride levels, and high turbidity. We have identified the industrial wastewater market as a sizeable market vertical to pursue, and have projects contracted with PFAS manufacturers and manufacturers who use PFAS in their processes. Landfills are another key market vertical, where HALT can be coupled with FF to provide PFAS separation, concentration, and destruction for complex landfill leachate matrices. Finally, the Department of Defense (DoD) has shown great interest in HALT for the destruction of environmental cleanup byproducts, including IXR still bottoms or FF concentrates produced during groundwater pump and treat projects, surface water treatment, fire training pond cleanups, bilgewater treatment, and soil washing projects.
Future technical development efforts will focus on (i) optimizing reactions temperatures to reduce required chemical consumption, (ii) investigating reactor longevity and mitigating component corrosion under harsh alkaline hydrothermal conditions, (iii) improving the overall integrated system design to account for loadings and forces during system transportation, and (iv) continuing to automate the system more completely for ease of operation. Aquagga has secured further R&D funding from the Defense Advanced Research Projects Agency (DARPA) and the National Science Foundation (NSF) to accomplish these future technical development goals.
Aquagga has also secured funding from the Defense Innovation Unit (DIU), the SERDP & ESTCP program, from the Federal Aviation Administration, and from the Washington Department of Ecology to demonstrate the TRL 6 HALT reactor at several field sites in 2023 and 2024, which would successfully transition the technology from TRL 6 to TRL 7. Field demonstrations are focused on using the HALT system designed and built in this SBIR Phase II effort to destroy a limited volume of PFAS-rich liquid concentrate (such as a foam fractionate) over several weeks to a month. Learnings from these field demonstrations will translate to iterations upon the system design and improvements upon Aquagga's product offerings, allowing us to ultimately offer both PFAS destruction services and PFAS destruction system sales to the environmental remediation and industrial wastewater treatment industries.
We are currently working with several private customers on bench testing and pilot demonstration efforts, including a paid project at an Air Force Base in California where PFAS in groundwater is being treated with foam fractionation, a paid commercial demonstration with a manufacturing client, and bench testing efforts with several complimentary technology vendors. Depending on the outcomes of these projects, we hope to secure larger contracts to provide fixed HALT systems to several of these clients in the near future.
SBIR Phase I:
Hydrothermal Alkaline Treatment of PFAS Contaminated Water and Groundwater | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.