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Effect of increasing anodic NaCl concentration on microbial fuel cell performance
Olivier Lefebvre1, Zi Tan, Shailesh Kharkwal
1Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Dr. 2, Singapore 117576, Singapore.
Bioresource Technology
|March 15, 2012
Summary
Adding salt up to 20 g L(-1) to microbial fuel cells boosts power production and reduces internal resistance. However, higher salt concentrations harm performance, and even moderate levels impact efficiency due to bacterial sensitivity.
Area of Science:
- Environmental science
- Electrochemistry
- Microbiology
Background:
- High salinity effluents constitute 5% of global wastewater.
- Increased salinity in microbial fuel cells (MFCs) can enhance conductivity and proton transfer, potentially improving power output.
- However, elevated salt concentrations can negatively impact anaerobic microbial consortia physiology.
Purpose of the Study:
- To investigate the effect of increasing sodium chloride (NaCl) concentration on MFC performance.
- To determine the optimal salinity range for MFC operation with sodium acetate as fuel.
- To assess the impact of salinity on internal resistance, power production, and Coulombic efficiency.
Main Methods:
- Microbial fuel cells were operated with sodium acetate as the substrate.
- Increasing concentrations of NaCl were added to the anode chamber.
- Key performance parameters including internal resistance, maximum power production, and Coulombic efficiency were measured.
Main Results:
- NaCl addition up to 20 g L(-1) enhanced MFC performance, decreasing internal resistance by 33% and increasing maximum power production by 30%.
- Salinity levels exceeding 20 g L(-1) proved detrimental to the system's overall performance.
- Coulombic efficiency was negatively affected at NaCl concentrations as low as 10 g L(-1), indicating sensitivity of anodophilic bacteria.
Conclusions:
- Moderate increases in salinity can be beneficial for MFC power generation by reducing internal resistance.
- There is an optimal salinity range for MFCs; concentrations above this threshold lead to performance degradation.
- Anodophilic bacteria in MFCs exhibit sensitivity to NaCl, with efficiency declining at relatively low salt concentrations, highlighting a critical operational parameter.
