Farzaneh Rezaei, Ag and Biological Engineering, Pennsylvania State University, 249 Ag Engineering Bldg, University Park, PA 16802, Tom L. Richard, Agricultural and Biological Engineering, Pennsylvania State University, 103 Land and Water Research Building, University Park, PA 16802, and Bruce E. Logan, Civil and Environmental Engineering, Pennsylvania State University, 231Q Sackett Bldg, University Park, PA 16802.
Microbial fuel cells (MFCs) are a promising technology for bioelectricity generation from a wide variety of organic and inorganic substrates in water, sediments, and wastewaters. However, little is known about the power densities and longevity of power generation in MFCs using particles such as lignocellulose and chitin, which are the two most abundant biomaterials in the world. These substrates degrade slowly over time and therefore can provide a long term source of fuel for MFCs. The effect of particle size on power and longevity was examined using chitin particles sieved to produce three average particle sizes. The length of a power cycle (longevity) in the MFC increased from 9 to 33 days with an increase in the particle diameter from 0.28 mm to 0.78 mm. Coulombic efficiency based on chitin removal increased from 18% for the smallest particles to 56% for the largest ones. The maximum power generation was lower for the largest particles (201 mW/m2), with higher power densities for the small particles (301 mW/m2) and 285 mW/m2 for the medium particles (0.46 mm). The measured lifetimes of these particles scaled with particle diameter to the 1.3 power. Based on modeling particles as spheres or fractals, it was determined that chitin particles were fractal with a three dimension fractal dimension (D3) between 2 and 2.3.
