WASHINGTON, DC, Oct. 8, 2015 -- DC Water has unveiled its $470-million waste-to-energy project that is producing a net 10 megawatts (MW) of electricity from the wastewater treatment process, ultimately providing clean, renewable energy to power about one-third of the Blue Plains plant's energy needs.
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 -- the CAMBI thermal hydrolysis process -- making Blue Plains the largest thermal hydrolysis installation in the world (see related article).
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. DC Water conducted more than a decade of research before bringing these facilities online. Their world-renowned wastewater research program includes dozens of researchers conducting their Ph.D. and masters theses on DC Water projects.
DC Water selected the PC/CDM Joint Venture, which brings together the industry-leading expertise in water treatment facility design and construction of PC Construction and CDM Smith to utilize the design-build delivery method to build the Cambi thermal hydrolysis process at the Blue Plains facility.
See also:
"DC Water to house world's largest deammonification system for advanced nitrogen removal"
"DC Water announces successful sale of $350M green century bonds"
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