EPA Research Partner Support Story: Air Emissions of PFAS at an Industrial Facility
Partner: North Carolina Department of Environmental Quality (NC DEQ)
Challenge: Air emissions of per- and polyfluoroalkyl substances (PFAS) at an industrial facility
Resource: Sampling thermal oxidizer and carbon beds
Project Period: 2023 – Present
North Carolina faces ongoing human health and environmental challenges due to pollution previously released during operations of the Chemours (formerly Dupont) Fayetteville Works chemical plant. Per- and poly fluoroalkyl substances (PFAS) emitted from that plant contaminated the Cape Fear River and drinking water throughout the region. In 2018, Chemours agreed to install numerous pollution controls to reduce PFAS emissions by more than 99%. The main pollution control is incineration, using a thermal oxidizer that destroys over 99.99% of the PFAS influent. In addition, carbon beds were also installed to reduce emissions that were released as fugitive emissions from inside various process containment buildings.
"Thank you for the copy of the OTM-50 Technical Memo summarizing the inlet and outlet emission concentrations for the carbon beds used at the Vinyl Ethers production areas (Vinyl Ethers North and Vinyl Ethers South) and the outlet of the Thermal Oxidizer. The OTM-50 data from the method development testing conducted by ORD at the Chemours Fayetteville Works will be most helpful in our review of emissions testing data versus air emissions inventory estimation procedures previously used for the facility operations.” – NC DEQ Engineer Gary Saunders
NC DEQ approached EPA ORD for assistance in determining the efficacy of the thermal oxidizer and carbon beds. NC DEQ was interested in components of PFAS substances that might not be destroyed by incineration, namely nonpolar fluorocarbons, as well as other volatile fluorinated byproducts that may be emitted from the thermal oxidizer. In addition, NC DEQ was interested in the degree of control that the carbon beds provided for other PFAS that were not or could not be measured by other existing test methods. ORD researchers applied a method still under development—known as Other Test Method (OTM)-50—to measure these additional volatile fluorinated compound emissions.
The OTM-50 results showed that only low levels (in the single digit parts per million range) of tetrafluoromethane were found in the oxidizer’s emissions. Carbon beds removed about 90% of the compounds that had boiling points around 100 °C. The total reduction of PFAS emissions from the plant using these controls are effective at meeting the permit’s 99% reduction in emissions. The volatile fluorinated compounds emitted were mainly low boiling point monomers used to synthesize various fluoropolymers, such as tetrafluoroethylene and hexafluoropropylene oxide. The volatile emissions from the carbon beds were in the parts per billion range and according to safety data sheets are safe at these levels, but more research may be needed into any potential health effects. This data is being used by NC DEQ to update the air emissions estimates and air permitting actions and activities associated with the Fayetteville Works facility.