| Turning Waste into Watts – Producing and Reducing Energy in US Wastewater Treatment with Austrian Knowledge |
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bridges vol. 21, April 2009 / Feature Articles By Thomas Wirthensohn mp3 download Wastewater treatment in the Washington, DC, area seems to be a family-run business: Sudhir Murthy, son of a wastewater engineer, is research director at the Blue Plains treatment facilities of the DC Water & Sewer Authority, while his wife, Maureen O'Shaughnessy, works at the Alexandria Sanitation Authority in Virginia, on the opposite shore of the Potomac River. One of the challenges the couple faces at work is how to achieve significant long-term reduction of their plants' energy needs. The most power-consuming process is the removal of nitrogen - a nutrient that gets into the wastewater every time you flush your toilet. 
Macroscopic view of Anammox bacteria.
The collaboration of Wett with the American scientists has already received well-deserved recognition for outstanding performance in the US: In February of this year, the US National Association of Clean Water Agencies (NACWA), the nation's biggest independent association for wastewater treatment, selected the DC Water & Sewer Authority together with the Alexandria Sanitation Authority to receive an award in the "Research & Technology" category of its annual National Environmental Achievements Program for "enhancing nitrogen removal and increasing sustainability with innovative sidestream treatment" using the Demon process. Blue Plains Advanced Wastewater Treatment Plant "We treat 300 million gallons of water a day," Murthy explains, while driving around the Blue Plains facilities. The distances are too long to 
Blue Plains - the largest Advanced Wastewater Treatment Plant in the US.
Wastewater treatment was invented 100 years ago, and Blue Plains was built in the 1930s. Back then, the removal of organic pollution - carbon (C) compounds - was considered sufficient treatment. "Otherwise these carbon compounds get degraded in the rivers or sea. Degradation is an oxygen-consuming process, the fish would die," says Murthy. In the 1970s, however, it turned out that removing the less bulky compounds nitrogen (N) and phosphorus (P) is even more critical (click here to access a "bridges" article with comprehensive background information on the different pollutants found in waste water). These nutrients fertilize the water bodies, thereby enhancing algal bloom, which is again followed by degradation and oxygen depletion. The Blue Plains treatment process (click here to access a "bridges" article with background information on Blue Plains "Advanced Wastewater Treatment") removes carbon and phosphorus and, since 2000, nitrogen as well. Additionally, a sand filter and disinfection by chlorination further improve the effluent quality. "Blue Plains is located at the nicest spot on the Potomac River; sometimes you can even see bald eagles," smiles Murthy. The effluent of the treatment plant has almost drinking water quality. Still, the Potomac River has environmental problems. Access to the full article is free, but requires you to register. Registration is simple and quick – all we need is your name and a valid e-mail address. We appreciate your interest in bridges. |
