There is an increasing demand for energy conversion devices such as fuel cells which can produce electricity from fuel and oxidants. Many combinations of fuel and oxidants are possible. A fuel cell may be a microbial fuel cell, hydrogen fuel cell or the like. A hydrogen cell may use hydrogen as fuel and oxygen as oxidant. Other fuels may include hydrocarbons, alcohols, and organic wastes. Other oxidants may include air, chlorine, chlorine dioxide or the like. A microbial fuel cell (MFC) (perhaps called biological fuel cell) may be a device in which microorganisms may oxidize compounds such as glucose, acetate, wastewater, or the like. Electrons gained from this oxidation may be transferred towards an electrode, called the anode. From the anode, the electrons may depart through an electrical circuit towards a second electrode, the cathode. At a cathode, the electrons may be transferred towards a high potential electron acceptor, such as for example, oxygen. As current may flow over a potential difference, power is generated as a result of bacterial activity or the like.
In the past, fuel cells have commonly used platinum as a catalyst. In U.S. Pat. No. 7,291,751 to Leiber et al, lead may be used as a supplemental promoter to perhaps enhance catalytic properties of a catalyst such as platinum. However, the Leiber patent does not discuss use with lead alone as a catalyst.
There is also an increasing need for new technologies applicable to cleaning up wastewater, groundwater and the like. Previous groundwater remediation systems may include air based remediation systems such as air sparging. Air sparging may commonly be used in remediation technology which may volatize and may even enhance aerobic biodegradation of contamination in groundwater and saturated zone soil. Air sparging may involve the injection of air under pressure into saturated zone soils. The injected air may displace water, create air-filled porosity in the saturated soils, which may volatize and remove dissolved and absorbed phase volatile organic compounds (VOCs), and may transfer oxygen into the groundwater. As a result, both physical removal and aerobic biodegradation of contamination in groundwater and saturated zone soil may be enhanced.
Other methods of degradation may include the use of a microbial fuel cell as mentioned above. A microbial fuel cell is a device that may generate electrical current by harnessing electron transport involved in anaerobic microbial metabolism. Past systems may include an upflow microbial fuel cell as discussed in U.S. publication no. 2006/147763 A1 to Angenent et al. This type of fuel cell may be difficult to use with in situ remediation of subsurface saturated and unsaturated zones.
Accordingly, there is a need for improved fuel cell systems and improved remediation treatments of contaminants.