Treatment plants release millions of gallons of wastewater into Maine’s waterways each day that could contain elevated levels of so-called forever chemicals that are used in a wide variety of consumer products and have been linked to long-term health and environmental risks.
But as Maine races to better understand how widespread its PFAS contamination problem is, particularly on farms and in landfills, there’s little known about the level of contamination in the wastewater these plants are releasing, nor about the concentration of forever chemicals building up in the Maine rivers onto which it’s released.
While the problem of PFAS contamination doesn’t originate with wastewater treatment plants, the facilities are a nexus in the state’s contamination problem. The sludge leftover from their treatment processes was spread on agricultural fields for decades, and there’s legislation pending now to permanently stop the practice. Plus, treatment plants receive runoff from the state’s landfills and industrial waste that testing has shown contain high concentrations of forever chemicals.
Maine has started to ramp up testing of soil and groundwater on farms where wastewater sludge was spread, and the state’s public drinking water systems have to test their sources for PFAS by the end of the year.
But there’s no systematic testing in place yet for wastewater and the waterways into which it’s flushed after treatment — such as the Penobscot River — pointing to another area where Maine still needs more data to determine how widespread PFAS contamination is and how to address it.
Scientists agree that there are PFAS in the water, but they don’t know the extent.
How PFAS get in wastewater
Forever chemicals make their way to wastewater treatment plants in a number of ways.
Industrial manufacturers have used the chemicals for decades in products ranging from non-stick cookware to waterproof clothing to food packaging. As a result, they end up in the industrial waste that ends up in wastewater treatment plants.
Liquid runoff from landfills also ends up at treatment plants.
In the state’s testing so far of PFAS contamination, liquid runoff from a landfill designated for waste from Twin Rivers Paper Company in Madawaska, which makes food packaging, had a higher concentration of forever chemicals than runoff from any other Maine-licensed landfill.
Forever chemicals also make it to wastewater treatment plants from people flushing their toilets and letting the water flow down the drain. The chemicals might come from the non-stick pans they’re washing and from people themselves, as they build up in our bodies over time and end up in human waste.
The chemicals are persistent and difficult to get rid of, which is what has made them attractive to manufacturers for years. But that’s also the quality that makes it such a challenge to deal with the contamination they cause.
Wastewater treatment plants make the water safe enough to pump back into a waterway, but they don’t treat it for PFAS, and they’re not required to, said Jean MacRae, an associate professor of civil and environmental engineering at the University of Maine.
“PFAS are not reliably removed in wastewater treatment, which is designed to remove more ‘normal’ organic matter…like food and feces, not so much these low-level, hard-to-degrade contaminants like PFAS,” she said. “So, unfortunately, you end up with contaminated water and contaminated solids.”
The treatment process, however, can capture some forever chemicals. As a result, they end up in the biosolid byproduct of wastewater treatment that’s more commonly known as sludge. That’s the substance that’s been spread on farmland for decades as compost. More recently, a growing amount of it has ended up in landfills as less has been spread on fields.
Water percolates through the contaminated sludge that ends up in the landfill, creating the runoff — called leachate — that testing has shown contains elevated levels of forever chemicals. That leachate then ends up in wastewater treatment plants that release the water back into the environment and capture some of the chemicals in sludge, repeating the cycle.
“Because there is not a requirement to test for these chemicals the amounts in local wastewater treatment facilities are not very well known, although the DEP is testing to try to better understand which sources are most important,” MacRae said.
A Maine Department of Environmental Protection spokesperson didn’t respond to a request for comment.
Research from experts at the University of New Hampshire has shed some light on the extent of PFAS contamination from wastewater treatment plants.
One study tracked different PFAS varieties through six treatment plants and determined plants were responsible for 10 percent of the PFAS contamination in New Hampshire’s Great Bay Estuary.
In another study, the team applied Maine’s recommended screening levels to sludge from treatment plants in New Hampshire and Vermont. The researchers found that 29 of the 39 sludge samples exceeded those levels.
More testing could be on the way
More testing to detect how much PFAS contamination is in Maine wastewater could be on the horizon.
Pending legislation that would permanently ban the spreading of sludge on Maine farmland, LD 1911, would also let the Department of Environmental Protection request information on PFAS contamination from any facility with a license to discharge wastewater.
“Getting a handle on how much PFAS from effluent ending up in our rivers, streams, and surface water is incredibly important and is information the state currently can’t access,” said Sarah Woodbury, the director of advocacy with the Portland organization Defend Our Health.
The new testing provision would be a beneficial next step, said Amanda Smith, the director of water quality in Bangor.
“We are the environmental steward when it comes to water for the Bangor area, so we have a vested interest in knowing what kind of pollutants are in that water, and how to go about removing them,” she said.