A microbial bioremediation platform for simultaneous removal of nitrogen, metals, and organic contaminants

Background

Biological nitrogen removal is a critical component of wastewater treatment and environmental remediation, aiming to mitigate the harmful effects of excess nitrogen compounds such as ammonium in water bodies. Elevated nitrogen levels can cause eutrophication, leading to algal blooms, hypoxia, and loss of aquatic biodiversity. Traditional nitrogen removal processes, such as nitrification and denitrification, typically require high energy inputs for aeration and are sensitive to environmental conditions like temperature and pH. Additionally, many contaminated sites and waste streams contain not only nitrogen but also heavy metals and persistent organic pollutants, necessitating integrated treatment solutions that can address multiple contaminants simultaneously.

Current approaches to nitrogen removal and contaminant degradation face significant limitations. Conventional biological processes are often ineffective under low-oxygen or acidic conditions and tend to perform poorly at low temperatures, restricting their application in certain climates and environments. Moreover, these systems generally require separate treatment stages for nitrogen, heavy metals, and organic pollutants, increasing complexity and operational costs. Many recalcitrant organic compounds, such as chlorinated solvents and aromatic hydrocarbons, are resistant to biodegradation under standard treatment conditions. As a result, there is a pressing need for robust, versatile technologies that can efficiently remove a broad spectrum of contaminants under challenging environmental conditions without the high energy demands of traditional methods.

Technology

This technology is an advanced bioremediation platform centered on the Feammox process, which employs the Acidimicrobiaceae bacterium strain A6 to simultaneously remove nitrogen, heavy metals, radionuclides, and recalcitrant organic contaminants from wastewater, soil, and groundwater. The core mechanism is anaerobic ammonium oxidation coupled with ferric iron reduction, facilitated by the unique Feammox Ammonium Monooxygenase (FMO) enzyme. This enzyme not only oxidizes ammonium to nitrite or nitrogen gas but also degrades hazardous organic pollutants such as trichloroethylene, perchloroethylene, benzene, and phenanthrene through epoxidation and oxygen insertion. The process operates under low-oxygen conditions, across a broad pH (2.0–7.5) and temperature range (4°C–35°C), and can utilize various ferric iron sources as electron acceptors. The technology is implemented in diverse reactor configurations—including membrane reactors, batch systems, and electrogenic microbial fuel cells—using live or lyophilized bacteria, and can be further extended through synthetic biology approaches to other organisms.

What differentiates this solution is its unique combination of versatility, energy efficiency, and robustness. Unlike conventional biological nitrogen removal systems that require energy-intensive aeration and are limited by pH or temperature, the Feammox process functions efficiently in acidic and low-temperature environments, making it suitable for a wide range of real-world conditions. Its ability to simultaneously address nitrogen, metals, and organic contaminants in a single anaerobic stage streamlines treatment processes and reduces operational complexity and costs. The integration with electrogenic systems allows for energy recovery in the form of electricity or hydrogen, further enhancing sustainability. Additionally, the availability of genetic tools for transferring the Feammox pathway into other hosts opens new avenues for tailored bioremediation and environmental engineering applications, making this technology a comprehensive and scalable solution for advanced environmental cleanup.

Benefits

• Efficient anaerobic removal of ammonium without the need for energy-intensive aeration, reducing operational costs.
• Simultaneous bioremediation of nitrogen, heavy metals (e.g., uranium, copper), and recalcitrant organic pollutants (e.g., TCE, PCE, benzene) in a single process.
• Operates effectively under acidic (pH 2.0–7.5) and low-temperature (4°C to 35°C) conditions, including environments where traditional treatments fail.
• Versatile integration with various reactor types, including membrane, batch, electrogenic microbial fuel cells, and microbial electrolysis cells for enhanced energy recovery.
• Utilizes a novel autotrophic bacterium and enzyme (Feammox Ammonium Monooxygenase) enabling CO₂ fixation and broad contaminant degradation capabilities.
• Applicable to diverse settings such as municipal, industrial, agricultural wastewater treatment, groundwater remediation, and engineered wetlands.
• Potential for synthetic biology applications to transfer Feammox capabilities to other organisms, expanding biotechnological uses.

Applications

• Municipal wastewater nitrogen removal
• Industrial groundwater bioremediation
• Heavy metal and radionuclide cleanup
• Degradation of chlorinated solvents
• Electrogenic wastewater treatment systems

Additional info

This technology utilizes *Acidimicrobiaceae* bacterium strain A6 for anaerobic ammonium oxidation coupled with ferric iron reduction. The Feammox Ammonium Monooxygenase enzyme converts ammonium to nitrogen gas while degrading organic pollutants like trichloroethylene via epoxidation. Operating at pH 2.0–7.5, the process simultaneously bioreduces heavy metals and radionuclides. It integrates into electrogenic reactors for energy-efficient wastewater treatment, providing a robust alternative to traditional aeration-based nitrogen removal.