DC Water revealed its US$470million waste-to-energy project, which aims to produce a net 10MW of electricity from the wastewater treatment process to provide clean, renewable energy for one-third of the blue Plains Plant’s power consumptions. The project was broke ground in 2011 and was the only one using such technology in America so far.
DC Water CEO and General Manager George S. Hawkins was joined by District of Columbia Mayor Muriel Bowser, Congresswoman Eleanor Holmes Norton, EPA Acting Deputy Administrator Stan Meiburg, U.S. Department of Energy Deputy Assistant Secretary Kathleen Hogan and local officials to commission the project.
The facilities include a dewatering building, 32 sleek thermal hydrolysis vessels, four concrete 80-foot high anaerobic digesters that hold 3.8 million gallons of solids each and three turbines the size of jet engines. DC Water brought the CAMBI® thermal hydrolysis process to the continent, and Blue Plains is now the largest thermal hydrolysis installation in the world. 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 to make the energy easily accessible to the organisms in the next stage of the process—anaerobic digestion. The methane these organisms produce is captured and fed to three large 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.
“This is yet another example of the District leading the nation in the adoption and implementation of sustainable practices,” said District of Columbia Mayor Muriel Bowser. “DC Water’s Blue Plains facility is converting waste to clean water and a nutrient-rich soil byproduct, producing energy and helping to put the District on the path towards a zero waste future.”
CEO and General Manager Hawkins said, “This project embodies a shift from treating used water as waste to leveraging it as a resource. We are proud to be the first to bring this innovation to North America for the benefit of our ratepayers, the industry and the environment.”