Generating electricity from wastewater treatment.

D uring the past 50 years, wastewater treatment has improved the quality of our navigable waters and the health of our environment. This achievement has not been accomplished without considerable capital investment by our nation, and we know that large expenditures will continue to be needed. It has been estimated that $2 trillion will be needed in the United States alone over the next 20 years for building, operating, and maintaining wastewater and drinking water facilities. Approximately $45 billion is needed for wastewater, in addition to the current annual expenditure of $25 billion. Where will we find such large reserves of funds for capital improvements and, even if we do, how will we justify the energy costs needed to run our wastewater treatment plants? Effective and efficient wastewater treatment is needed not just in the United States, but everywhere in a world as 2 billion people lack access to adequate sanitation. We are engaged in a new era of globalization, in which disease from one remote part of the world is only a plane ride away from anywhere else in the world. Wastewater treatment is not just a responsibility within the United States, but around the world. How will less industrialized and affluent nations afford to spend relatively enormous amounts of money on wastewater treatment? The technology of choice for domestic wastewater treatment in the United States is activated sludge, an energy-intensive aerobic process developed more than a century ago. How can we make so many advances in transportation, fuels, electronics, and other fields, and yet rely on the same basic process developed so long ago? It is clearly time to reexamine the energy costs of aerobic wastewater treatment systems and develop more innovative and less energy-consuming approaches. recommended that new wastewater treatment processes be developed that could produce products with a market value. Until recently, however, it was not clear what types of processes or products might fit this need. The discovery of the direct generation of electricity using bacteria in microbial fuel cells (MFCs), however, could change this. Microbial fuel cells have been used to generate electricity from virtually any biodegradable organic matter, including human, animal, and industrial wastewaters, while at the same time accomplishing wastewater treatment. No special bacteria or chemicals need to be added to a wastewater to achieve treatment. The generation of electricity is based on the fact that bacteria derive energy from the oxidation …