| Electricity can be generated from forest residues, especially the organic matter from litter fall, in freshwater forested wetland environments with a microbial fuel cell (MFC) system. Electricity generation efficiency was examined for cypress, tupelo, and pine litter extracts, using dual-chamber reactors. The maximum power density generated with cypress extracts was on the level of 320 mW/m2, higher than tupelo (230 mW/m 2), and pine (210 mW/m2). The efficacy of cypress extracts was also higher than tupelo and pine, demonstrating that organic matter from cypress litter is a preferred substrate for electricity generation with MFCs. Meanwhile, low aromaticity of the substrate was advantageous to the power generation in MFC, as examined in cypress extract. Power generated in the column reactors had a positive relationship with temperature, whereas there was a negative relationship with electrode distance. In a field situation, power generation using sediment MFCs depended mainly on temperature when temperatures were lower than 10--15 °C; but depended more on substrate characteristics (especially concentrations of DOC and SUVA) than temperature when temperatures were higher. Based on the lab study, the annul energy input from dissolved organic matter from litter fall to the studied wetland is 16.74 GJ, of which 4.12% can be utilized with current sediment MFCs technology as used in this study. However, power density is still too low, two orders of magnitude lower than dual-chamber reactors can deliver. |
