The phrase “flush down the toilet” is one applied with a markedly high frequency to Washington, D.C. — and usually in reference to dignity, taxpayer dollars and political careers. And anthrax.

Now, thanks to an innovative waste-to-energy project at the District of Columbia Water and Sewer Authority’s Blue Plains Advanced Wastewater Treatment Plant, each individual flush will help to usher in a new era of clean energy production … the era of poop power.

It’s certainly fun to imagine that DC Water’s aforementioned project, a $470 million scheme capable of generating 10 megawatts of electricity from the wastewater treatment process, would help to power the District itself from the floodlights of the Lincoln Memorial to the desk lamps of the Oval Office to the battery chargers for those pesky Segways zipping up and down the Constitution Avenue. Just think — congressional offices powered by crap!

Alas, the groundbreaking renewable energy project, the first of its kind in North America, will only provide power to the 157-acre Blue Plains facility located in Southwest D.C., just across the Potomac River from Alexandria. Established in 1938 as a means of halting the discharge of raw sewage into the Potomac and other local waterways, the plant, which also services the District-abutting suburbs of Maryland and Virginia, is the largest advanced water treatment facility in the world — and the largest single consumer of electricity in Washington, D.C.

Norway-developed Cambi thermal hydrolysis technology, a space-saving two-step process best described as the pressure-cooking of sewage sludge, will provide the facility with a third of its electricity needs — not everything but a decent dent — while dramatically reducing the energy-hungry plant's overall carbon footprint.

Through the in-house conversion of excreta to energy, DC Water is poised to save in the ballpark of $10 million annually in electricity costs. The utility will also save an additional several million dollars each year that are normally earmarked for treatment chemicals and hauling expenses.

Thermal hydrolysis reactors at Blue Plains Advanced Wastewater Treatment Facility in Washington, D.C.The just-unveiled thermal hydrolysis installation at Washington, D.C.'s Blue Plains Advanced Water Treatment Plant is the first in North America and the largest in the world. (Photo: DC Water)

"It’s a huge deal on so many fronts,” George S. Hawkins, general manager for DC Water, declared last week during a ceremony in which the 5-acre, four-years-in-the-making project was unveiled to the public. “It’s a public utility leading the world in innovation and technology. We have private and public water companies coming from all over the world to see this.”

While converting methane into energy via anaerobic digestion isn’t exactly new, this specific thermal hydrolysis process is, as mentioned, new to the United States. Numerous thermal hydrolysis plants can be found across the United Kingdom and in several other European countries, Norway included. Several more are slated to launch in China in the coming years.

With 32 sleek Cambi vessels up and running, Washington, D.C., for now, is now home to the largest thermal hydrolysis installation in the entire world. And given that the Blue Plains facility processes 370 million gallons of wastewater each day, there’s more that enough solids to keep those bacteria-eliminating Norwegian reactors a-cookin’.

Some, err, easy to digest background from DC Water:

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 and the structure between cells 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.

This graphic produced by the Washington Post provides additional insight into the process, starting from the very beginning: the commodes of our nation's capital.

In addition to renewable energy, the process also churns out a cleaner, higher quality of biosolids — aka the sludgy gunk leftover from the wastewater treatment process — and less of it.

Thermal hydrolysis reactors at Blue Plains Advanced Wastewater Treatment Facility in Washington, D.CWith its new facility, DC Water will reduce greenhouse gas emissions by 50,000 tons of CO2e equivalent metric tons — the same as removing 100 million car miles from the road. (Photo: DC Water)

As reported by the Post, Blue Plains produced roughly 1,200 tons of pungent Class B biosolids daily previous to the thermal hydrolysis installation. Now, the facility will generate approximately half that amount, about 600 tons, of pathogen-free Class A biosolids. While Class B biosolids, which are treated but still contain some pathogens, must be exported daily via truck to remote farms for agricultural use, less stinky and more versatile Class A biosolids can stay closer to home and be used for urban gardening and landscaping projects. DC Water eventually plans to market and sell these water treatment leftovers commercially as a nutrient-rich soil amendment.

DC Water anticipates that its annual biosolids hauling bill will be slashed by an impressive $11 million thanks to the upgrade from Class B to Class A.

"This is yet another example of the District leading the nation in the adoption and implementation of sustainable practices," said D.C. Mayor Muriel Bowser in a press statement. "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."

Washington D.C.'s thermal hydrolysis project is no doubt an example of sustainable innovation at its finest. But one does wonder if DC Waters’ customers will also start seeing savings in their monthly water bills. Will the bundles of cash being saved by the utility be passed on to customers? After all, they’re the ones doing all the pooping.

Via [Washington Post]

Matt Hickman ( @mattyhick ) writes about design, architecture and the intersection between the natural world and the built environment.

Thermal hydrolysis is transforming Beltway BMs into electricity
Pressure-cooked sewage sludge will help DC Water save $10 million annually in electric costs.