DC Water uses technology to convert wastewater to energy
DC Water recently unveiled a $470 million waste-to-energy project that is producing a net 10 megawatts (MW) of electricity from the wastewater treatment process, providing clean, renewable energy to power about one-third of the Washington, D.C., Blue Plains plant's energy needs, according to a press release.
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, according to the release. 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 the organisms produce is captured and fed to three large turbines to produce electricity. Steam also is captured and directed back into the process.
The solids at the end of the process are a cleaner Class A biosolids product DC Water uses as a compost-like material. Biosolids products are being used around the district for urban gardens and green infrastructure projects.
"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," District of Columbia Mayor Muriel Bowser said.
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