Wastewater-to-Energy plant opened in Washington, DC

DC Water opened its US$470 million waste-to-energy project that produces a net 10 megawatts (MW) of electricity from the wastewater treatment process. The project provides power to Blue Plains, Washington, DC.

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.”

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.

The project, which broke ground in 2011, was only viable through the use of innovative technology never before used in North America. 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.