Understanding nitrogen recovery from wastewater with a high nitrogen concentration using microbial electrolysis cells

Area of Science:

• Environmental Engineering
• Biotechnology
• Waste Management

Background:

• Nitrogen recovery from organic waste is crucial for sustainable agriculture and environmental protection.
• Microbial electrolysis cells (MECs) offer a promising technology for nutrient recovery from waste streams.

Purpose of the Study:

• To investigate the impact of applied voltage, catholyte type, and reactor scale on nitrogen recovery efficiency using MECs.
• To identify key factors limiting nitrogen recovery from digestate and pig slurry.

Main Methods:

• Testing MECs of varying sizes (100, 500, 1000 mL) with different applied voltages (0.6, 1, 1.4 V).
• Utilizing phosphate-buffered solution and NaCl solution as catholytes.
• Analyzing nitrogen recovery efficiency from digestate and pig slurry.

Main Results:

• Increasing reactor size from 500 to 1000 mL decreased ammonia recovery efficiency from 47% to 42%.
• Phosphate-buffered solution proved to be a more effective catholyte compared to NaCl solution.
• Applied voltage did not significantly influence current production or ammonia recovery.

Conclusions:

• Reactor scale and catholyte choice significantly impact nitrogen recovery in MECs.
• Low biodegradability of organic wastes is a primary limitation for efficient nitrogen recovery.
• Optimizing MEC operation requires consideration of waste characteristics and reactor design.