Saint-Gobain's regenerative thermal oxidizer

Saint-Gobain Performance Plastic’s new regenerative thermal oxidizer has three chambers to maximize filtration efforts before emissions escape the blue tower.

New analysis shows the new pollution-reduction equipment at the Saint-Gobain plant is keeping polluting emissions below state-set thresholds, though the state and federal environmental officials are still conducting their own analysis.

After hundreds of wells for miles around the Saint-Gobain Performance Plastics Merrimack factory were found to be contaminated with per- and polyfluoroalkyl substances, often called PFAS or “forever chemicals,” the company was ordered to install equipment to clean its emissions of pollutants.

The equipment, a regenerative thermal oxidizer, is designed to reduce PFAS emissions by 90%, breaking down the chemicals by heating them to more than 1,800 degrees.

The oxidizer was installed in July 2021, months after a state-ordered deadline, which Saint-Gobain had said was impossible to meet because of supply-chain issues. The state sued the company in March, but the parties reached an agreement out of court.

Tests conducted in September show the oxidizer is keeping emissions below what the state Department of Environmental Services deems acceptable limits.

An outside engineering firm collected the samples, supervised by state environmental officials. Another outside company analyzed the samples for PFAS and other pollutants, according to the Department of Environmental Services.

The engineering firm’s report on the tests found the emissions of pollutants are below the thresholds set by the state in permits for Saint-Gobain’s facility.

The New Hampshire Department of Environmental Services is still reviewing the report, and the U.S. Environmental Protection Agency is analyzing additional samples.