Microbial fuel cell for bio-electricity generation with optimisation on electrode and biological factors

• Main Author: Tan, Serene Xufeng.
• Other Authors: Wang Jing-Yuan
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Environmental engineering
• Online Access: http://hdl.handle.net/10356/15996
• Institution: Nanyang Technological University

Microbial fuel cell (MFC) is a novel biotechnology that converts chemical energy to electrical energy with the help of bacteria, and organic substrates as the fuel. This green technology produces electricity and also cleans wastewater at the same time. Therefore MFC technology has unique advantages that are unrivalled by other waste-to-energy technologies. However current applications of MFC are restrained by very low power density. Some literature reviews have suggested that one of the ways to significantly improve discharge performance is through electrode modifications on the anode. Therefore this project will attempt to modify the anode using carbon nanotubes (CNT). Dissimilatory metal reducing bacteria (DMRB) donate electrons to anode through their outer-membrane-bound c-type cytochromes, and thus are vital for MFC anodic electron transfer. The DMRB adopted in this project is Shewanella oneidensis. Linear sweep voltammetry (LSV) was used to measure the current output and it was conducted immediately after inoculation to determine the discharge performance of the system. Cyclic voltammetry (CV) analysis was also conducted for better understanding of the electrochemical system qualitatively. After LSV and CV analysis, scanning electron microscopy (SEM) was also carried out to observe the physical effects of multi walled carbon nanotube (MWCNT) on the electrode and graphite sheets From the results, it was observed that when the anode was modified with 3 drops of MWCNT, the best discharge performance was achieved. It was also found that with 3 drops of MWCNT, the surface was the roughest and least homogeneous as compared to the others, and large aggregates were observed. This trend was evident in both the SEM images of modified electrode and modified graphite sheets, which proves that 3 drops of MWCNT was the optimum amount. In conclusion, this project has successfully attempted to characterise the anode with carbon nanotubes and achieved excellent discharge performance with DMRB in half cell reactors. The anode modified with 3 drops of MWCNT produced discharge performance which was 3 times better than the blank electrode which was not characterised with any MWCNT, and this clearly demonstrated the benefits of characterising the electrode with CNT. 3drops of MWCNT was also the optimum amount as it was 12.5 times better than the lowest discharge performance of 5 drops of MWCNT.