• Maine Launches Pioneering Plan to Eradicate PFAS in Sewage Sludge


Maine Launches Pioneering Plan to Eradicate PFAS in Sewage Sludge

Jun 03 2023

There’s a stereotype of the residents of Maine, New England, as simple fisherfolk, merrily going about lives that haven’t changed all that much for many generations. But through the activities of the Portland Water District (PWD), these simple fisherfolk have found themselves at the cutting-edge of environmental science.  

One of the scourges of modern ecosystems are per- and polyfluoroalkyl substances, or PFAS (or “forever chemicals”). Around 15,000 different pollutants fall under this categorisation, almost all of which are synthetic chemicals manufactured for their ability to protect products from water, stains, and heat – as such, PFAS are virtually ubiquitous in our daily lives. Worryingly, though, there’s a mounting body of evidence that even very small durations of exposure to PFAS can spur the development of cancers, birth defects, and autoimmune diseases. It’s these substances that Maine authorities have broken new ground in eliminating. But how? 

Well, the project focusses, perhaps surprisingly, on sewage sludge, a residual product of the water treatment process. As you might expect, this sludge is incredibly nutrient-rich, and this was a problem when standard practice was to dump into the ocean, as this richness threw marine ecosystems into catastrophic meltdown, turning these dumping grounds into lifeless dead-zones. But it’s a bonus now that it’s more commonly used as fertiliser – after being cleansed of the worst pathogens, of course. There’s a catch, though, and a rather big one: it’s chock-full of PFAS. As a result, this fertiliser serves as yet another vector for PFAS contamination, further exposing consumers of agricultural goods to the harmful effects of these substances. It’s believed that around 20mn acres of North American farmland have been contaminated in this way, poisoning 2% of the United States’ agricultural acreage.  

Clearly, then, a solution is desperately needed. At first, Maine forged ahead by banning the use of sewage sludge as fertiliser - but that left authorities with huge quantities of toxic material that they now had no way of getting rid of. Portland Water District’s Director of Wastewater Services, Scott Firmin has publicly underscored the District’s commitment to the safe disposal of sewage sludge as a critical element in protecting environmental and public safety but as things stand, Maine’s only option has been to send a certain portion of their sludge for processing out of state, costing the public a significant fee. In the meantime, the District is exploring a broad range of approaches to countering the threat of PFAS contamination via sewage sludge, including the construction of a facility for high-temperature neutralisation techniques like pyrolysis and gasification (after which the charred sludge will remain adequate for fertiliser), as well as freeze-drying the sludge before neutralising it, and simply reducing the frequency of landfill dispatches.  

There are plenty of skeptics who doubt the scalability and efficacy of these solutions, though. Despite the authorities’ claims, whether or not PFAS are eliminated by such processes is fraught with uncertainty as these techniques might only dissimulate certain compounds without properly neutralising them in the process. Moreover, there are some potentially toxic by-products of the high-heat procedures, specifically. In general, such processes always produce both residual matter and substances that threaten air quality, too. Nevertheless, this research may yet produce some fruitful solutions and Portland Water District is utterly committed to being at the forefront of this technology. 

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IET 33.5 Sept/Oct 2023

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