The District of Columbia’s water utility, DC Water, has unveiled a $470 million waste-to-energy project that will produce a net 10 megawatts (MW) of electricity from the wastewater treatment process. The result is energy that powers approximately one-third of the Blue Plains treatment plant’s energy requirements.
The project began in 2011 and brought in new technology to North America such as the CAMBI thermal hydrolysis process. Thermal hydrolysis uses high heat and pressure to “pressure cook” the solids left over at the end of the wastewater treatment process. This weakens the solids’ cell walls and the structure between cells to make the energy more easily accessible to organisms in the next stage of the process, anaerobic digestion. The methane these organisms produce is captured and fed to three turbines to produce electricity. Steam is also captured and directed back into the process.
Finally, the solids at the end of the process are a cleaner Class A biosolids product that DC Water uses as a compost-like material. Biosolids products are currently being used around the District for urban gardens and green infrastructure projects. DC Water is also working to bring a compost-like product to market.
The project was based on more than a decade of research before bringing these facilities online. The project also received a 2012 Grand Prize in Planning Award from the American Academy of Environmental Engineers & Scientists, a 2012 Global Honor Award in Planning from the International Water Association and a WERF Excellence in Innovation Award was presented in 2011.
http://insights.globalspec.com/article/1580/water-utility-inaugurates-waste-to-energy-project