Read the full article by Marina Schauffler (The Maine Monitor)
“To many bureaucrats and wastewater managers in the 1970s and ’80s, spreading municipal and industrial sludge onto Maine’s farms and forests seemed like an inspired solution to a vexing problem.
Recycling held strong appeal to many people, and returning nitrogen-rich waste to the soil could boost agricultural productivity without the need for expensive fertilizers. Care had to be taken to test for heavy metals, proponents noted, but they believed spreading human waste on farm fields, an age-old practice in many cultures, was safe and sustainable.
Sludge spreading was also a relatively cheap means of disposal. After the Clean Water Act passed in 1972, ‘the focus was on cleaning up rivers and streams and not so much on what we do with the residuals,’ said Steve Page, who went to work in 1988 for a new recycling division within the Maine Department of Environmental Protection (DEP) that oversaw sludge and septage (the concentrated waste pumped from septic tanks).
‘Diagrams of early wastewater treatment plants would show a complicated flow chart that always ended with a picture of a dump truck. End of problem,’ Page said. But for plant operators and regulators, that’s where the problem began. Those truckloads of sludge accumulated quickly and disposal options were limited.
Congress banned ocean dumping of sludge in 1988, and landfills and incinerators did not want this wet byproduct of sewage treatment. It was ‘hugely expensive to dewater sludge,’ Page said, and trucking it to nearby lands helped keep sewer rates down. It was ‘by far a cost-driven thing,’ he added, ‘with the altruistic benefit of providing what was thought to be a safe fertilizer to farmers.’
No one generating sewage or managing sludge in Maine at that time realized the material contained per- and polyfluoroalkyl substances (PFAS), a vast class of synthetic chemicals that can disrupt hormonal, immune and reproductive systems, and can increase the risk of various cancers. What seemed at the time like an economical solution to sludge disposal became a monumentally costly environmental threat, with repercussions extending far into the future.
Sludge to soil
By the 1970s, PFAS were a growing constituent in the waste stream, having been used in consumer products and industrial processes for more than a decade. But health risks from these persistent chemicals were known only to manufacturers like 3M and DuPont, which conducted their own toxicity studies.
The U.S. Environmental Protection Agency (EPA) eventually pressured manufacturers to phase out production of two widely used ‘long-chain’ PFAS chemicals (with many carbon atoms), PFOA and PFOS. The corporations then launched a new generation of shorter-chain compounds, which were marketed as safer but now appear more mobile, more water-soluble and more readily taken up by plants.
PFOA and PFOS can form from other chemical precursors in settings like wastewater treatment plants, said Jean MacRae, a professor of civil and environmental engineering at the University of Maine. Researchers have found that these two ‘legacy’ compounds tend to concentrate in sludge; they are predominant among the PFAS compounds being found in Maine farm soils where sludge was applied, according to Ellen Mallory, a University of Maine agronomist.
During the 1980s and ’90s as sludge-spreading expanded throughout New England, ‘land application was far and away greatest in Maine,’ Page said. Two-thirds or more of all the state’s municipal sludge generated annually was spread onto soils, and in some years that figure rose over 85 percent. In 2019, a single waste company involved in ‘direct land application’ noted that it had ‘over 200 farm customers in the state of Maine.’
That practice ended this year when Maine enacted a first-in-the-nation ban on the spreading of sludge and the sale of compost derived from sludge. But through the preceding half-century, PFAS had seeped into soils and groundwater, creating what Page terms ‘generations worth of problems for agriculture.'” …