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Up Close With Saint-Gobain's New PFAS Chemical Treatment System In Merrimack

saint gobain oxidizer
Annie Ropeik
The regenerative thermal oxidizer will burn PFAS chemicals from Saint-Gobain's air emissions in Merrimack. It replaces the factory's old smokestacks, like the one seen at far top left.

The Saint-Gobain factory in Merrimack is putting the finishing touches on a big new air emissions treatment system, a state-mandated upgrade designed to burn off harmful PFAS chemicals that represents a first for the company.

They unveiled the new system to reporters as part of a factory tour on Tuesday.

Saint-Gobain Unveils PFAS Treatment System
Hear NHPR All Things Considered host Peter Biello speak with Annie Ropeik about her tour of Saint-Gobain and the new chemical treatment system.

Inside the plant, Saint-Gobain's signature protective fabrics were being woven on giant looms and coated with chemicals that include kinds of PFAS, also known as "forever chemicals."

The substances are linked to health problems and persist in the environment. New Hampshire is one of the few states that regulate PFAS in drinking water, but they remain common in consumer products and aren't subject to federal limits.

saint gobain biohazard suit
Annie Ropeik
Saint-Gobain makes protective fabrics treated with PFAS chemicals for products like this biohazard suit, on display in the lobby of the company's Merrimack factory.

Saint-Gobain uses the substances to make fabrics that resist chemicals, fire and the elements for military and emergency gear – biohazard suits and desert shelters, for example – and construction uses, such as weather-proof sports stadium rooftops.

“We make products here [in Merrimack] we don’t make at other facilities,” said Chris Angier, the company’s regional environmental health safety manager. “There’s kind of some unique things that take place here.”

After Saint-Gobain’s PFAS use in Merrimack caused contamination in hundreds of nearby water wells several years ago, state regulators ordered the company to install the new air emissions treatment system.

Saint-Gobain missed its first deadline this past February. The final deadline is July 30, 2021.

"A very difficult time"

The company said the $5.3-million project marks the first time they’ve used this technology, called a regenerative thermal oxidizer, to treat PFAS at their facilities. It’s more commonly used to eradicate volatile organic compounds, which are also toxic.

The oxidizer replaces all of the factory’s old rooftop smokestacks with a large system of ducts, heating chambers and a bright blue tower on the outside of the building. It includes three large ovens, which collect PFAS-laden air and burn off the chemicals at more than 1,800°F.

The system is now ramping up to its required temperature and capacity, and the company says it will be fully operational by the state’s deadline.

Saint-Gobain’s Merrimack plant manager Gabriel Caridade said the project has taken 32,000 labor hours to complete, almost all over the past four months, often including six- or seven-day work weeks. He said he and his workers are glad the project is done.

“This has been a very difficult time for them,” he said at the factory Tuesday. “We are very proud of this.

gabriel caridade saint gobain
Annie Ropeik
Saint-Gobain Merrimack plant manager Gabriel Caridade stands near the new PFAS air treatment system.

Angier, the environmental safety manager, said he’s confident the device will address local concerns about pollution from the plant.

“It’ll destroy PFAS, it’ll meet the state-required conditions,” he said, “so I’m optimistic.”

Waiting for proof

Town officials want to see the data to prove that the new system is effective, after years of tension with the factory, which they called a public nuisance in a recent lawsuit.

“It’s great that it’s being finalized, finally,” Merrimack town council chair Tom Koenig said Wednesday. “We are definitely waiting for the required studies to formalize the functionality of all this.”

Those studies will include a company analysis of the oxidizer’s hydrogen fluoride emissions, which the town wants addressed with a scrubber to prevent further health risks.

The company is also completing a state-mandated study of PFAS in rainwater around the facility, and it’s still installing new water lines for neighbors with contaminated wells.

The permit for the air oxidizer includes a 60-day follow-up period in which the company will gather data for the state on whether the system is working as expected.

The plant reduced its operating hours by about 40%, without furloughing workers, while the oxidizer was under construction, in order to reduce PFAS emissions to state specifications. They say they’ll return to full strength once the system is finalized next week.

Annie has covered the environment, energy, climate change and the Seacoast region for NHPR since 2017. She leads the newsroom's climate reporting project, By Degrees.

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