Biodegradation of PFAS via Feammox (Ammonium Oxidation Under Iron Reducing Conditions)

Background

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals widely used in industrial and consumer products due to their resistance to heat, water, and oil. Their unique chemical stability, stemming from strong carbon-fluorine bonds, has led to their persistence in the environment, earning them the nickname “forever chemicals.” PFAS contamination is now a global concern, as these compounds accumulate in water sources, soil, and living organisms, posing significant health risks such as cancer, immune system disruption, and developmental issues. The urgent need for effective PFAS remediation technologies arises from their environmental persistence, widespread distribution, and the limitations of conventional water and soil treatment methods to adequately remove or destroy these compounds.

Current approaches to PFAS remediation, such as activated carbon adsorption, ion exchange, and high-pressure membrane filtration, primarily focus on separating PFAS from water or soil rather than destroying them. These methods generate secondary waste streams that require further handling and disposal, often through incineration or landfilling, which can be costly and potentially lead to incomplete destruction or environmental release. Advanced oxidation and reductive processes, while capable of breaking some PFAS bonds, often require extreme conditions (high temperature, pressure, or chemical inputs) and may not achieve complete mineralization, especially for short-chain PFAS. Additionally, these chemical and physical methods can be energy-intensive and may produce toxic byproducts, highlighting the need for more sustainable, effective, and comprehensive solutions for PFAS degradation.

Technology

This technology leverages the unique metabolic capabilities of the Acidimicrobiaceae bacterium strain A6 and its associated reductive dehalogenase enzymes to achieve the mineralization of per- and polyfluoroalkyl substances (PFAS) into harmless end products such as carbon dioxide, fluoride ions, and water. The system operates under anaerobic conditions within a temperature range of 4°C to 35°C and a pH range of 2.0 to 8.0, making it suitable for diverse environmental applications including water, soil, and sludge remediation. The process is highly adaptable, utilizing ammonium, molecular hydrogen, or organic compounds as electron donors, while Fe(III), a bioelectrochemical anode, or the fluorine atoms within PFAS serve as electron acceptors. The technology can be implemented in both batch and continuous reactors, and is further enhanced by electron shuttling compounds and physical supports to optimize bacterial activity and biofilm formation.

What differentiates this solution is its biological approach to breaking the notoriously strong carbon-fluorine bonds in PFAS, a feat that has challenged conventional chemical and physical remediation methods. By harnessing the Feammox process—ammonium oxidation coupled to iron reduction—facilitated by strain A6 or its isolated enzymes, the technology achieves direct defluorination and mineralization of a wide spectrum of PFAS compounds. Its versatility in electron donor and acceptor selection allows for tailored deployment in various contaminated environments, including those lacking ammonium or rich in iron. Experimental validation demonstrates not only the survival and activity of the bacteria at high PFAS concentrations, but also the direct correlation between PFAS degradation and fluoride ion release, confirming complete mineralization. This biologically driven, modular, and scalable approach offers a significant advancement over existing PFAS remediation strategies, providing an effective, sustainable, and site-adaptable solution for persistent environmental pollutants.

Benefits

• Effective mineralization of persistent PFAS pollutants into harmless end products (carbon dioxide, fluoride ions, and water)
• Utilizes specialized *Acidimicrobiaceae* bacterium strain A6 or its enzymes for targeted carbon-fluorine bond cleavage
• Operates under mild anaerobic conditions (4°C to 35°C, pH 2.0 to 8.0), suitable for diverse environmental media including water, soil, and sludge
• Flexible electron donor options (ammonium, molecular hydrogen, or organic compounds) enable application in various contaminated sites
• Electron acceptor versatility, including Fe(III) minerals or bioelectrochemical anodes, allows adaptation to different treatment systems
• Applicable in batch or continuous reactors, scalable for industrial or environmental remediation use
• Demonstrated reduction of multiple PFAS types, including PFOA, PFOS, and fluorotelomer compounds
• Supports biofilm formation and enhanced electron transfer for improved degradation efficiency

Applications

• Groundwater PFAS remediation
• Industrial wastewater PFAS treatment
• Contaminated soil PFAS cleanup
• Sludge PFAS detoxification

Additional info

This bioremediation technology utilizes *Acidimicrobiaceae* bacterium strain A6 and reductive dehalogenase enzymes to mineralize per- and polyfluoroalkyl substances. By coupling electron donor oxidation—ammonium, hydrogen, or organics—with the reduction of Fe(III), anodes, or fluorine, the system cleaves carbon-fluorine bonds. Operating anaerobically between pH 2.0–8.0 and 4°C–35°C, it converts persistent fluorochemicals into carbon dioxide, fluoride ions, and water across diverse environmental media.