D.C. Water aims to redefine meaning of ‘sludge’
WASHINGTON — Blue Plains is the largest and most advanced wastewater treatment plant in North America.
On an average day, more than 300 gallons of raw sewage flow through the Blue Plains Advanced Wastewater Treatment Plant, enough to fill nearby RFK Stadium on a daily basis.
Anything and everything that gets flushed down the toilet or flows into stormwater drains in D.C. Water’s 725 square mile service area passes through the facility.
At peak wet weather capacity, the plant can treat more than one billion gallons of sewage daily.
In the 2000s, DC Water invested about $1 billion to upgrade the Blue Plains facility and technology. Wastewater generated by more than 2 million people goes through a complex treatment process to clarify the water and separate organic matter.
Clean water is discharged into the Potomac River, eventually flowing into the Chesapeake Bay.
The organic matter is treated through thermal hydrolysis, using high heat and pressure to eliminate pathogens and prepare microbes for the anaerobic digesters.
The digesters convert the organic matter into methane, which is used to generate electricity to power the plant, and Class A biosolids, marketed by the name Bloom, which are applied to the land.
Bloom is sold in small quantities to homeowners for garden and lawn use and in bulk quantities to soil blenders, landscapers, governments and farmers.
“We are one of 20 facilities like this in the world,” said Bloom’s program manager, Saul Kinter.
Historically, applying human waste to farmland has been met with resistance from farmers, communities, and environmentalists.
The use of sludge stirs up all kinds of questions about safety, heavy metal residue, traces of hormones and antibiotics and the presence of anything else that people might have flushed down the toilet.
Kinter said his team at Bloom is working to change those perceptions.
“Among the general public, the initial reaction is ‘eew,’” he said. “But you have to get in front of it. We’re out there with baggies of Bloom, explaining the process and in the end, people end up saying, ‘that’s really something.’”
In Maryland, Charles County farmer Steve Walter began using Bloom on his crops last year. He said so far, he’s been pleased.
“They know the product and technology really well,” Walter said of the Bloom team. “They don’t know ag as well, but we’re getting there.”
To help increase the knowledge and understanding of how Bloom can benefit farmers, the company partnered with Walter and the University of Maryland Extension to conduct on-farm field tests.
At a field day on Walter’s farm in Hughesville, University of Maryland Extension educator Ben Beale of St. Mary’s County, explained the test was intended to gather data on utility and benefit of the Bloom product for farmers who wanted to use it.
Beale and nutriment management specialists from Charles and St. Mary’s counties divided an 11-acre field into 12 rows.
Corn was planted on May 26. Two no-nitrogen control rows were established, along with two rows that received urea-only. Bloom was applied on the remaining rows at varying rates from 3.4 tons to 17 tons to the acre.
Beale said the preliminary results show positive results with fairly good nitrogen release. He noted that Bloom demonstrated increased levels of zinc and sulfur in the soil.
Like other biosolids, Beale said, Bloom is high in phosphorus. He said it’s important to work with your nutrient management advisor to determine the appropriate application rate.
The most important data is yield, Beale said, which won’t be available until after the harvest.
He said he and his fellow researchers are looking forward to collecting that information this fall.
“Bloom is as affordable as any alternative source of nutrients,” said Bill Brower, Bloom’s manager of resource recovery. “We really want people to try it. We’re producing a lot of it…it comes in every day.”
Brower noted that when using Bloom, farmers are subject to any normal regulatory standards, but noting additional.
Blue Drop, the company that markets Bloom in cooperation with DC Water, has the permits and conducts laboratory tests to ensure the products safety and compliance with EPA standards.
“The regulatory environment has been a barrier in the past, but with the high quality product we’re producing and our permit, we’re doing our best to demonstrate this is a safe and effective tool,” Kinter said.
Walter is the largest agricultural buyer for Bloom in the state of Maryland. He said in the past, he was resistant to using sludge because of the regulatory concerns, but also because he didn’t want to approach the subject with his landowners.
“How am I going to ask them if I can put something on their land when I won’t even use it at my own house?” Walter said.
Because of the quality of the product and sustainability efforts that DC Water has in place at Blue Plains, Walter said the conversations are much easier.
“In fact, they’re excited,” Walter said.
And so far, he said he’s been satisfied with the results he’s getting.
“Time will tell,” Walter said. “But so far, I think it’s making a difference and the price is certainly right.”
Kinter was quick to note that Bloom isn’t a free product.
“We’re not giving it away,” he said. “It’s valuable. It’s recycled. It’s locally produced. And it’s a sustainable source that’s going to be around for a long time. Right now, we want to get more people trying it out.”
The cost of Bloom for agricultural customers varies from $3/ton with delivery in Montgomery and Prince George’s County to $5 per ton with delivery in central Maryland and the Eastern Shore. The cost is $4 a ton for delivery to Southern Maryland.
Farmers and the public still raise concerns about the presence of heavy metals or pharmaceutical residue. Kinter said these are valid concerns, but that the product consistently demonstrates its safety in laboratory tests.
“The dose makes the poison,” Kinter said. “Are those things there? Yes. But we’re talking very trace amounts — parts per million and parts per billion — we didn’t even have the ability to test at those levels until recently.”
Kinter said along with Walter, Bloom has relationships with a Maryland tree nursery and local construction companies. Homestead Garden in Davidsonville also uses Bloom in their greenhouse operation and has acquired equipment to dry and bag the product for retail sale to homeowners.
“Our view is that the treatment plant isn’t going anywhere and neither are farmers, hopefully,” Kinter said. “There’s a mutually beneficial relationship here and one we hope to grow.”
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P.O. Box 2026 Easton, MD 21601-8925