Nitrogen removal from wastewater using membrane aerated microbial fuel cell techniques.

Area of Science:

• Environmental Science
• Environmental Engineering
• Microbiology

Background:

• Nitrogen removal in wastewater treatment typically involves sequential nitrification and denitrification.
• Microbial fuel cells (MFCs) offer a dual approach for wastewater treatment and energy generation.

Purpose of the Study:

• To evaluate membrane-aerated MFCs (MAMFCs) and diffuser-aerated MFCs (DAMFCs) for simultaneous pollutant removal and electricity production.
• To investigate the impact of dissolved oxygen (DO) levels on nitrogen removal efficiency in MFC systems.

Main Methods:

• Construction and operation of bench-scale MAMFC and DAMFC systems over 210 days.
• Monitoring of chemical oxygen demand (COD), ammonia, and total nitrogen removal.
• Analysis of ammonia-oxidizing bacteria (AOB) populations using terminal restriction fragment length polymorphism (T-RFLP).
• Measurement of voltage output from both reactor types under varying DO conditions.

Main Results:

• Both MAMFC and DAMFC achieved high COD (>99%) and ammonia (>99%) removal at 2 mg/L DO.
• Lowering DO to 0.5 mg/L improved nitrogen removal in MAMFC (52%) significantly more than in DAMFC (24%).
• MAMFC demonstrated higher AOB diversity and superior average voltage output compared to DAMFC.

Conclusions:

• MAMFC systems show potential for enhanced nitrogen removal and electricity production in wastewater treatment.
• Optimizing DO levels in the cathodic compartment of MAMFCs can improve denitrification efficiency.
• The study highlights the advantages of MAMFCs over DAMFCs for combined wastewater treatment and energy recovery.