Bloom made headlines again this September, being featured in the Dow Jones podcast MarketWatch: Best New Ideas in Money, hosted by reporter Charles Passy and economist Stephanie Kelton. In an episode entitled Are we wasting our waste?, the podcast covered the rich opportunities in recycling human waste, generating fertilizer, heating and even crude oil, through technologies that are both financially and environmentally sustainable. The excerpt featuring DC Water is transcribed below.
“We don’t look at it as waste anymore; it’s not a liability; it’s an asset.”
That’s Chris Peot, an engineer with DC Water in Washington, DC. DC Water’s Blue Plains is one of the largest advanced wastewater treatment plants in the world. When a plant is advanced, it means it is able to remove the extra nutrition from the water that wreaks havoc on the environment. Peot says the plant has invested heavily in new technology to make their waste treatment more environmental and efficient, spending $470 million dollars. That includes spending on new technology called thermal hydrolysis processing, and four enormous anaerobic digesters. This process works by first applying high heat and pressure to destroy pathogens and reduce odors. Then, inside the digesters, microbes break down the organic matter. In this process, biogas is produced and heat is recovered. The gas is harvested, and used to power other processes. The heat is sent back to the beginning, where it’s used to kill pathogens. That means the plant is now running on more than 50% renewable energy. And that translates into huge energy savings.
“We’re the biggest single site user of electricity in DC, because of the pumps and blowers that we have here.”
Another benefit from using the digesters? The microbes eat away at the solids, cutting the initial amount of sludge in half. What’s left is turned into a high quality soil product, those biosolids we’ve talked about.
“And really, for me, it just returns back to the earth from which it came. That’s kind of the way the earth is supposed to work. We’re not supposed to take all these carbon and nutrients and lock it into a landfill. It’s really supposed to go back on the land. So we’re putting carbon back on the land, we’re bringing the nutrients back, we’re completing that nutrient cycle and that carbon cycle that other animals do – we’re part of the ecosystem too.”
One final project to mention? Heating or cooling homes using the heat from sewage.
“It sounds kind of disgusting but it’s not, what we do is we pull sewage up, we put it through a heat exchanger, and we heat clean water and then that water goes up into the building and heats the building. We have a building, our headquarters, and one other building in DC that are 100% heated in the wintertime with heat recovered from the sewers.”
Peot and his team are working on a project that would expand sewage heating to new developments in public housing in the area. All these investments were costly, but because the plant is able to save money, and create revenue from soil, energy, and heat, and by selling renewable energy credits, they expect to make that money back in 15 years. That’s of course depending on where energy prices go from here. Ultimately, whatever we do with our waste, one thing is for sure: thinking of it as a waste is a waste. Here’s Chris Peot, again.
“It’s an asset that every city in the nation has flowing beneath its feet.”