Emission-free, Low-maintenance and Low-energy Nitrate Water Remediation Using Microbial Fuel Cell Technology

Fertilizer is required for increasing crop productivity and gives farmers economic viability. However, the use of nitrogen-based fertilizers results in excess nitrate runoff in the ground water, and has the potential to cause significant health problems if consumed in large quantities. There is an increasing body of evidence that nitrate pollution of ground water is a large and growing problem around the world especially in rural communities where fertilizers are used. Particularly alarming is a recent study by the University of California Davis which quantifies and summarizes groundwater nitrate occurrence in the Tulare Lake Basin and Salinas Valley in California. The study shows instances where the maximum contaminant level set by the EPA is being exceeded in those areas. Other locations in the U.S. have also experienced the impact of nitrate contamination in water wells, including Minnesota and Texas. Current technologies for home or even full-scale treatment of drinking water have a host of problems including high operating cost, high maintenance requirements, and high water waste. Additionally, most of the current technologies do not remediate the nitrate, and so do not contribute to solving the long-term problem of nitrate accumulation in the ecosystem. Remediation is the preferred choice, because with continued use of nitrogen-based fertilizers the nitrate accumulation problem will grow, having the largest effect on rural communities and farmers.The proposed cost-effective, low-maintenance, and green technology uses a microbial fuel cell to remediate nitrate in drinking water. This device consumes hydrogen as an energy source and converts nitrate to benign nitrogen gas and water. The hydrogen will be produced via electrolysis of water, which also enables a carbon free cycle. The results of a Phase 1 project will be a proof-of-concept device and material/system strategies which will be used to build a prototype home water treatment system in Phase 2. Initial economic estimates show that if the Phase 2 targets are met, even at the small scale, this technology is cost competitive making home/family farm well water treatment systems a good early market opportunity. Additionally, it is expected that both the capital and operating cost will decrease significantly with increasing scale, as it does with other electrochemical systems. Therefore, larger more centralized treatment systems can also be envisioned.