DC Water commissions new $470m waste-to-energy project

7 October 2015 (Last Updated October 7th, 2015 18:30)

DC Water has commissioned its $470m project that produces a net 10MW of green electricity from wastewater treatment processes.

DC Water has commissioned its $470m project that produces a net 10MW of green electricity from wastewater treatment processes.

The facility generates enough renewable energy to meet one-third of that required by the enerBlue Plains power plant in the district of Columbia, US.

Initiated in 2011, the project includes a dewatering building, 32 sleek thermal hydrolysis vessels, four concrete, 80ft-high anaerobic digesters that hold 3.8 million gallons of solids each, and three turbines the size of jet engines.

District of Columbia Mayor Muriel Bowser said: "DC Waters 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."

"The cleaner biosolids can be applied locally, saving millions of dollars in hauling costs."

DC Water CEO and general manager George Hawkins said "This project embodies a shift from treating used water as waste to leveraging it as a resource."

CAMBI thermal hydrolysis process uses high-heat and pressure to ‘pressure cook’ the solids left by the wastewater treatment process. This weakens the cell walls and inter-cell structures to simplfy the organisms for the next stage, anaerobic digestion.

Methane produced by the organisms is captured and fed to three large turbines to produce electricity. Steam is also captured and directed back into the process.

Solids remaining at the end are the cleaner Class A biosolid product used by the authority as a compost-like material, with the future aim of launching it onto the market.

Biosolids are said to being used around the district for urban gardens and green infrastructure projects.

DC Water board chair Matthew Brown said: "The board of directors approved this voluntary investment to create a better class of biosolids and generate 10MW of power to cut the electricity bill at the Blue Plains plant, which is the single largest consumer of electricity in the district.

"Additionally, the cleaner biosolids can be applied locally, saving millions of dollars in hauling costs."