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Building a Microbial Fuel Cell

The design decisions pertaining to and the construction of

a prototype microbial fuel cell..

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Contact Team BioVolt

 

Lindsay Arnold

lga2@students.calvin.edu

 

Jeff Christians

jac28@students.calvin.edu

 

Diane Esquivel

dse2@students.calvin.edu

 

Andrew Huizenga

awh5@students.calvin.edu

 

The Feed

Design Process The final design of this cell will incorporate widely available materials. After extensive trials and experiments, the bacteria were found to grow well in a media containing primarily water, table salt, baking soda, and vinegar. The feed also contains sodium phosphate and ammonium chloride. These two chemicals are necessary for cellular growth, providing the bacteria with a phosphate source and nitrogen souce. No suitable substitute was found for these two nutrients, however, both chemicals are relatively inexpensive and widely available.

 

The Bacteria

Design Process Through a literature review, BioVolt decided to base the prototype MFC off of Geobacter Sulfurreducens. This bacteria was chosen because of the acetate feed which could be used (i.e. vinegar) and the fact that it has shown good power production with plain graphite electrodes.

 

Cell Design

One main design consideration in the cell design is the choice of electrode. The electrodes for both the anode and cathode of the prototype were chosen to be plain graphite. These electrodes were chosen because graphite had the potential for longer life-time, because it does not become oxidized, than other materials such as stainless steel. For a final production model it is suggested that the cathode electrodes be replaced with platinum loaded graphite electrodes. The platinum coating on the graphite electrodes serves to catalyze the reduction of molecular oxygen to water, thus increasing overall cell power. Platinum loaded graphite was not employed in the prototype cell because Calvin College does not have the proper facilites to manufacture such electrodes.

Design Process

The overall architecture of the cell employs a media storage chamber along with the anod and cathode. The media storage chamber allows the user to run the MFC in a semi-batch mode. In the set-up, the user adds new media to the anode using the injection pump. The injection pump draws media from the media storage chamber, passes it through a filter to filter out any bacteria or other contaminants, and pumps it into the anode. Used media is then removed from the anode through a waste stream. This system allows the user to operate the MFC without exposing the bacteria to high levels of oxygen, UV light, or other species of bacteria, allowing for prolonged operation.

Below is a diagram of BioVolt's final prototype showing the media storage chamber, the anode, and the cathode as well as the components of each chamber.

Design Process

 

Cell Components

Design Process Design Process The final prototype is constructed of polyvinyl chloride (PVC) pipe for the main body of the cell. The electrodes, shown at left, are made of graphite rods with copper wire connected. All exposed metal is covered in silicon to isolate it electrically from the media solution.

The filters which are used in the prototype, shown at right, are 0.22 micron filters. These filters provide a small enough pore size that all contaiminants, including bacteria, can be filtered out before the media is injected into the anode.

 

Power Output

Design Process BioVolt's final prototype cell produces 0.5 micro watts of power at a voltage of approximately 650mV. The voltages obtianed from the prototype are close to the theoretical maximum obtained by the employed biology, and the low power output is a direct result of BioVolt's choice to use plain graphite for the cathodic electrodes. Had platinmun electrodes been employed in the prototype, BioVolt anticipates that this power could be multiplied 1,000-10,000 times current levels.

 

 

Project Feasability

While the final prototype cell demonstrated the feasability of MFCs as power sources, more work must be done before MFCs become viable options for commercial applications. The low power displayed by the prototype is the major hurdle which must be overcome before widespread implimentation is feasible. Several possibilities exist for increasing this power production. First, the use of a catalyst on the cathode electrodes is a simple way to increase power production up to 10,000 times that of BioVolt's prototype. Also, using a bacterial cocktail with several different bacterial species has shown potential to increase power output a further 100 times. Further research is needed into these, and other, possibilities; however, BioVolt's prototype MFC has shown that MFCs have the potential for adoption in low power applications.

 

Sources

Team EcoWatt PPFS http://knightvision.calvin.edu/bbcswebdav/orgs/ENGR/senior-projects/2007-08/Team10/

AATC. (n.d.). The Global Biosource Center. Retrieved from American Type Culture Collection: www.atcc.org

Amherst, U. o. (2009). Retrieved from Geobacter Project: http://geobacter.org/

Behera, M., Jana, P. S., & Ghangrekar, M. (2010). Performance evaluation of low cost microbial fuel cell fabricated using earthen pot with biotic and abiotic cathode. Bioresource Technology (101), 1183-1189.

Chung, K., & Okabe, S. (2009). Continuous power generation and microbial community structure of the anode biofilms in a three-stage microbial fuel cell system. Applied Microbial Biotechnology (83), 965-977.

Dewan, A., Donovan, C., Heo, D., & Beyenal, H. (2010). Evaluating the performance of microbial fuel cells powering electronic devices. Journal of Power Sources (195), 90-96.

Du, Z., Li, H., & Gu, T. (2007). A state of the art review on microbial fuel cells: A promising technology for wastewater treatment and bioenergy. Biotechnology Advances (25), 464-482.

Dumas, C., Basseguy, R., & Bergel, A. (2008). Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes. Electrochimica Acta (53), 2494-2500.

EHSO. (2009, 11 16). Battery Disposal Guide for Households. Retrieved from Environment, Health and Safety Online: http://www.ehso.com/ehshome/batteries.php#types

El Jalil, M., Faid, M., & Elyachioui, M. (2001). A biotechnological process for treatment and recycling poultry wastes manure as a feed ingredient. Biomass and Bioenergy (21), 301-309.

Kim, B.-C., Postier, B. L., DiDonato, R. J., Chaudhuri, S. K., Nevin, K. P., & Lovley, D. R. (2008). Insights into genes involved in electricity generation in Geobacter sulfurreducens via whole genome microarray analysis of the OmcF-deficient mutant. Bioelectrochemistry (73), 70-75.

Li, H., Feng, Y., Zou, X., & Luo, X. (2009). Study on microbial reduction of vanadium metallurgical waste water. Hydrometallurgy (99), 13-17.

Rabaey, K., & Verstraete, W. (2005). Microbial fuel cells: novel biotechnology for energy generation. TRENDS in Biotechnology , 23 (6), 291-298.

San, Ka-Ya. Bioreactors in Biochemical and Metabolic Engineering. Ed. Nic Leipzig. Rice University, 15 Sept. 2004. Web. www-bioc.rice.edu/ <11 May 2010>

Sony Develops 'Bio Battery' Generating Electricity from Sugar. Physorg.com, 23 Aug. 2007. Web. http://www.physorg.com/news107101014.html <11 May 2010.>

Trinh, N. T., Park, J. H., & Kim, B.-W. (2009). Increased generation of electricity in a microbial fuel cell using Geobacter sulfurreducens. Korean J. Chem. Eng. (26), 748-753.

 


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