Microenvironment-engineered electrified membrane for reactive separation of ammonia from wastewater

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Source-separated recovery of nitrogen pollutants is crucial for nitrogen circularity and reducing wastewater infrastructure load.
• Existing electrochemical systems often face challenges in balancing high flux with low energy consumption for nitrogen recovery.

Purpose of the Study:

• To develop a novel reagent-free electrified membrane system for efficient and low-energy ammonia (NH3) recovery from wastewater.
• To optimize the system for high flux, stability, and practical, decentralized deployment.

Main Methods:

• An electrified membrane was engineered to generate interfacial alkalinity via water dissociation, facilitating ammonium (NH4+) to ammonia (NH3) conversion.
• Integrated microenvironment-engineering was employed to enhance alkalinity and reduce gas-transport resistance.
• Performance was evaluated based on NH3 separation rate, energy consumption, and long-term operational stability over 500 hours.

Main Results:

• The electrified membrane demonstrated the highest reported NH3 separation rate among electrochemical recovery systems.
• The system achieved an average NH3 separation rate 2.9 times higher than conventional structures.
• The membrane retained 87.5% of its initial performance after 500 hours of continuous operation, indicating excellent stability.

Conclusions:

• The developed electrified membrane offers a promising solution for efficient, low-energy ammonia recovery and nitrogen circularity.
• The system's high performance, stability, and potential for decentralized application were confirmed through preliminary assessments.
• This work establishes a framework for electrochemical ammonia separation, paving the way for practical, decentralized wastewater treatment solutions.