AbstractsBiology & Animal Science

Developing new wastewater treatment technologies which will off-set the high-energy cost associated with treatment is necessary to maintain both water and energy security. Microbial fuel cell technology represents one such option. However, there are still many obstacles to overcome before practical application of this technology can be realized. Improving cathode and reactor design while lowering cost and increasing performance will remove two major obstacles to scale-up and move MFC technology one-step closer to practical application. Metal supporting materials are increasingly being used as base materials for microbial fuel cell (MFC) cathodes. However, the potential for corrosion may limit their use as base materials of MFCs during scale-up and long-term operation. In the first study included in this dissertation, the electrochemical performance, power generation in MFCs, hydrostatic pressure tolerance, and stability of activated carbon (catalyst) cathodes with carbon cloth or different size metal mesh as base materials were investigated. Electrochemical testing results showed that the finest stainless steel mesh (250x250 openings per inch) outperformed carbon cloth cathodes by 10-40% at current densities ranging from 6 to 11.2 A m⁻² over the typical cathode operating range of 0.1 V to 0 V. When tested in MFCs, however, carbon cloth based cathodes out performed all stainless steel mesh cathodes by as much as 34%, reaching 1.72 W m⁻²; probably due to the corrosion and salt build-up on the surface of the stainless steel mesh cathodes. Carbon cloth cathodes also maintained high static pressure heads of 1.9 m. The high electrochemical performance, hydrostatic pressure tolerance, and corrosion resistance of carbon cloth suggest that carbon fiber based materials may be more suitable than metal based materials for use as MFC cathodes base material for some applications. Replacing precious metal catalysts by inexpensive activated carbon (AC) is a breakthrough in microbial fuel cell (MFC) cathode fabrication. In the next study covered by this dissertation, activated carbon powders made from bamboo, peat, coal, coconut, and hardwood sources were characterized in terms of their surface area, pore size distribution, surface chemistry, and conductivity to better understand the linkages between the physical and chemical properties of AC and their electrochemical performance with carbon cloth as the base material. The bamboo-based AC demonstrates the highest potential for use as a catalyst for carbon cloth based cathode, reaching -10.6 A m⁻² and 11.27 A m⁻² at 0V with loading of 25mg cm⁻² and 50mg cm⁻², respectively. The maximum power density reached 3.3 W m⁻² in CEA-MFCs and 2.6 W m⁻² in cube-MFCs, respectively. These power densities are much higher than that typically reported for single-chamber MFCs with activated carbon catalysts. The higher proportion of micorpore surface area/volume, higher conductivity, and lower C/O ratio may all contribute to the higher performance. These results demonstrate that…