Every day, Baltimore sewage funnels into a building at the Back River Wastewater Treatment Plant, where a local company processes it into dark sludge and ships it to farms, to be spread over cropland.
Known in the industry as “biosolids,” the sewage sludge from Baltimore-area homes and businesses has helped crops grow this way for decades, providing a cheap and nutrient-rich alternative to traditional fertilizers.
But the practice faces new scrutiny across the country.
Sewage sludge can contain high concentrations of dangerous compounds. Known as “forever chemicals,” these human-made toxins are found everywhere, don’t break down in the environment and can lead to birth defects and cancer.
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A growing movement of farmers is concerned about these per- and polyfluoroalkyl substances, or PFAS, contaminating crops, water and livestock.
But those potential dangers didn’t stop Baltimore officials last month from renewing their agreement with one of the country’s leading manufacturers of wastewater sludge, Middle River-based Synagro Technologies.
At a meeting of the city’s Board of Estimates, public works officials stressed that Synagro’s process is critical to operations at Back River, the largest wastewater treatment plant in Maryland, and leaders unanimously approved a $53 million agreement to continue the company’s operation at Back River for four more years.
Not mentioned, though, were the company’s legal fights elsewhere. Last year, a group of Texas ranchers alleged that forever chemicals in Synagro’s sewage sludge poisoned their water and killed their cows. The Texas county where these ranchers live subsequently opened a criminal investigation.
Brent Walls, the Upper Potomac Riverkeeper, said there hasn’t been a backlash to Synagro’s business in Maryland because the state hasn’t done similar testing to reveal PFAS contamination on its farmland.
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That doesn’t mean it’s less hazardous, he said.
Walls has advocated in Annapolis for tighter regulations on wastewater PFAS and said nobody — from corporations to government leaders to wastewater utilities — seems willing to crack down on forever chemicals. Synagro, he said, neglects to warn consumers about the hazards in its product, even as it profits.
“They’re not being honest, they’re not being truthful and they’re not being fair,” Walls said.
In response to emailed questions, Synagro said it has voluntarily complied with tiered PFAS guidance instituted by the Maryland Department of the Environment, but believes that more data is needed on forever chemicals in biosolids before the state sets any regulatory limits.
Headquartered in an unassuming office park in eastern Baltimore County, Synagro has a sprawling business. Purchased by a Goldman Sachs-managed investment fund in 2020, the company helps manage biosolids and other waste functions in more than 30 U.S. and Canadian cities.
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Where exactly Synagro’s product winds up after leaving Maryland wastewater plants — it operates at both of Baltimore’s treatments plants, Back River and Patapsco, among others — isn’t clear. The company is the only biosolids supplier in Maryland, according to the MDE. Agency data shows Maryland generated more than 600,000 tons of wastewater sludge in 2024, with more than half of it hauled out of state.
Last month, Synagro asked a federal judge to dismiss the Texas lawsuit. It also has promoted a new study, without sharing the report, concluding that its product couldn’t have caused the high PFAS levels found in the ranchers’ dead cattle.
Days later, though, nearby Fort Worth broke off a 10-year contract with Synagro at its wastewater treatment plan, where the company manufactured sludge for Texas farms.
Synagro said in its statement that the decision to end the contract was mutual and not related to PFAS or the ranchers’ lawsuit. Fort Worth’s water utility took over the biosolids operation there on April 5, Synagro said. A Fort Worth spokesperson similarly called the decision mutual and unrelated to the ranchers’ lawsuit.
While Synagro has acknowledged the challenges of PFAS for its industry, it argued that regulators should aim to eliminate the chemicals before they get into the waste stream. In a recent sustainability report, the company called itself a “passive receiver” of the harmful chemicals.
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The U.S. Environmental Protection Agency has yet to release formal guidance on using wastewater sludge on farmland, but some states have taken matters into their own hands. Maine banned the practice in 2022. Maryland last year imposed a moratorium on new agricultural permits for wastewater sludge, and now requires wastewater plants to test sludge for PFAS before it’s applied to farmland, an MDE spokesman said.
Maryland Sen. Sara Love thinks the state needs even stricter rules.
The Montgomery County Democrat introduced a bill in the recently concluded General Assembly session to limit two harmful forever chemicals on farmland to a stringent 1 part per billion — the safety threshold laid out in a draft risk assessment from the EPA.
Even after advocates agreed to a compromise, setting PFAS limits at a level most of Maryland’s wastewater plants already meet, Love said municipal utilities opposed her bill, which failed to make it out of committee.
“The answer cannot be that we as Marylanders have to pay with our health,” Love said.
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The conclusion for companies like Synagro can’t be that removing PFAS is too hard, she added, “therefore we’re going to continue to put poison on our agricultural land.”
State sampling of wastewater sludge at municipal plants shows these chemicals are widespread. A 2023 MDE report shows that on average, concentrations of two harmful PFAS strains were many times above the EPA’s preliminary guidance.
At last month’s Board of Estimates meeting, Baltimore public works officials acknowledged the challenge that PFAS regulations could pose to its already beleaguered wastewater purification systems.
Synagro has operated its facility in a corner of the sprawling Back River plant since 1991, drying solids at the end of the treatment process and turning them into fertilizer pellets, which it sells to agricultural and industrial customers.
The company handles 70% of the solid waste that passes through Back River, said Matthew Garbark, the interim public works deputy director. Synagro’s facility runs around the clock, and without it, the plant would back up.
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Michael Hallmen, the city’s deputy wastewater bureau head, said officials are exploring options for different contractors at Back River after the extended contract expires in 2029. Synagro’s lease there doesn’t expire until 2030.
The regulatory environment for PFAS is a “moving target,” Hallmen told city leaders, adding that cracking down the chemicals would be expensive.
Building a facility at Back River to handle PFAS would cost north of $100 million, Hallmen said, while a city public works spokesperson pointed to a study by Minnesota regulators that found removing PFAS from wastewater would cost up to millions of dollars per pound.
“Placing the regulatory burden solely on utilities is both impractical and financially unsustainable,” Mary Stewart, the spokeswoman, said in a statement.
While Synagro plays down the hazards of its business publicly, its leadership has taken steps to respond to mounting pressure.
On Capitol Hill, the company has helped lead a lobbying campaign to insulate itself from lawsuits like the one in Texas, The New York Times reported in December.
Meanwhile, at Back River, Synagro plans to test a new method that would use extreme heat to destroy PFAS, according to its latest sustainability report.
Things are running a bit behind schedule, city officials said. They expect Synagro to begin testing the technology next month.
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