Treating refinery wastewaters in microbial fuel cells using separator electrode assembly or spaced electrode...

Area of Science:

• Environmental Science
• Electrochemistry
• Biotechnology

Background:

• Refinery wastewater (RW) poses significant environmental challenges due to its complex organic pollutants.
• Conventional wastewater treatment methods may struggle with the recalcitrant nature of RW.
• Microbial fuel cells (MFCs) offer a promising bioelectrochemical approach for wastewater treatment and energy recovery.

Purpose of the Study:

• To evaluate the efficacy of air-cathode MFCs for treating refinery wastewater.
• To compare the performance of different MFC configurations (SEA vs. SPA) in terms of power generation and organic removal.
• To assess the impact of oxygen crossover on the degradation of organic pollutants in RW within MFCs.

Main Methods:

• Two MFC configurations, separator electrode assembly (SEA) and spaced electrode (SPA), were employed.
• Power production (power density and volumetric power) was measured for each configuration.
• Organic removal was quantified by measuring total COD, soluble COD, and HBOD.
• Performance was benchmarked against a domestic wastewater control and previous microbial electrolysis cell (MEC) tests.

Main Results:

• The SEA configuration yielded higher maximum power density (280±6 mW/m(2)) than the SPA configuration (255±2 mW/m(2)) due to lower internal resistance.
• MFCs demonstrated significant organic removal: up to 84% total COD, 73% soluble COD, and 92% HBOD.
• Power output was lower with RW compared to domestic wastewater, suggesting lower biodegradability of RW.
• Organic removal efficiencies surpassed those achieved in previous MEC tests, indicating enhanced degradation in MFCs.

Conclusions:

• Air-cathode MFCs are effective for refinery wastewater treatment, achieving substantial organic matter removal.
• The SEA configuration is superior for power generation in MFCs treating RW.
• Oxygen crossover in MFCs plays a beneficial role in enhancing organic pollutant degradation compared to anaerobic MECs.