Potential applications for our project could be used in both developed and developing countries for industry such as:
The waste water from such factories could be used as the main carbon source for our synthetic Escherichia coli. In doing so will reduce the level of toxicity of the waste water and produce a green energy source which will offset the heavy reliance of fossil fuels. It also offers potential to extract useful chemicals from wastewater, such as hydrogen and bioplastics.
However, the performance of this system is currently poor, typically <10% of what is theoretically possible. In addition, energy recovery by MFCs from treatment of Industrial wastewater including brewery wastewater, azo-dye wastewater, municipal wastewater and other sources is still poor typically less than 150W/m3 of the anode volume and for potential sustainable operation, energy recovery need to reach 1000W/m3.
One the current issues regarding the energy output are resolved, the size of the fuel cell will need to be up scaled in order to accommodate the high level of waste produced by the factory, but also to produce an adequate yield of electricity in order to offset the energy used from other power sources during the manufacturing process. The initial costs of implementing such a bioreactor will be expensive. However, once the system is in place, the reduction in costs related to wastewater clean-up and the offset of electrical energy used during the product manufacture, should cover all the debt incurred for the system set up. Not only can this new form of renewable energy save money for companies that are dealing with a high rate of wastewater disposal, but also most importantly, it can reduce the reliance on fossil fuels.
This application is not just reserved for industries listed previously. It has been estimated that domestic waste water contains 9.3 times as much energy that is currently used to treat it (Logan, 2009). This adds another element to the viable uses of the system- wastewater treatment for sewage and water companies.
In 2007, Foster’s Brewery together with University of Queensland and University of Ghent, designed the first MFC using brewery wastewater as the organic carbon source for their microorganisms. Professor Keller and his team had positive results using a 10 litre prototype. This project was a small to medium sized scale (1000 litre) and was set up to better understand possible problems that could occur in relation to scaling up the system. There is little information regarding the performance of the MFC in the study other than that the anode appeared to become obsolete due to an excessive build up of biofilm on the cathode (Logan, 2010). Despite setbacks experienced with the scale up during this project, research must continue in order to develop solutions that can overcome such issues in the future.
Further applications could also include the use of promoters that can eliminate heavy metals from wastewater, such as lead and copper promoters. Adapting the promoter to the requirements of the wastewater may improve the efficiency of the MFC in decontaminating wastewater, and may also produce by-products such as caustic soda (Logan, 2010). This by-product can then be used in a variety of other product manufacturing processes. For instance, paper and pulp mills caustic soda is used in the bleaching and pulping stage (Logan, 2010).
Logan, B. E. (2009). Exoelectrogenic bacteria that power microbial fuel cells. Nature Reviews Microbiology, 7(5), 375-381.
Logan, B, E. (2010). Scaling up microbial fuel cells and other bioelectrochemical systems. Appl Microbiol Biotechnol. 85: 1165-1671