Microbial fuel cells for simultaneous carbon and nitrogen removal

Area of Science:

• Environmental Science
• Biotechnology
• Electrochemistry

Background:

• Microbial fuel cells (MFCs) offer potential for wastewater treatment.
• Nitrogen removal from wastewater is a critical environmental challenge.
• Existing methods often require high carbon input and energy consumption.

Purpose of the Study:

• To design and demonstrate a novel MFC-based process for simultaneous carbon and nitrogen removal.
• To evaluate the efficiency of nitrogen removal and energy production.
• To compare the MFC process with conventional activated sludge systems.

Main Methods:

• A two-stage process involving an anodic carbon-utilizing stage and a cathodic nitrate reduction stage in an MFC.
• Nitrification of ammonium in an external aerobic reactor followed by denitrification at the MFC cathode.
• Continuous monitoring of removal rates, power output, and current density.

Main Results:

• Achieved removal rates of 2 kg chemical oxygen demand (COD) m(-3)NCC d(-1) and 0.41 kg NO(3)(-)-N m(-3)NCC d(-1).
• MFC produced a maximum power output of 34.6 Wm(-3)NCC and current of 133.3 Am(-3)NCC.
• Demonstrated a reduced COD/N ratio of approximately 4.5 g COD g(-1) N compared to conventional systems.

Conclusions:

• The MFC-based process efficiently removes both carbon and nitrogen from wastewater.
• The process offers significant advantages in reduced carbon requirements and energy efficiency.
• Potential for further optimization using nitrite as a cathodic electron acceptor was identified.