Emissions Testing for PFAS Removal Demonstration by a Solids Treatment Unit

Opportunity

Montrose Environmental was contracted to determine PFAS removal efficiency by a novel, non-combustion batch process from Aqueous Film Forming Foam (AFFF)-spiked solid material. The process was a volatilization and capture process.

Montrose was selected due to our expertise in sampling for complex compound matrices containing dioxins, PAHs, PCBs and PFAS, and our Montrose-own Enthalpy Analytical Laboratories (EAL) for expertise in PFAS analysis and method development. The demonstration test was conducted in at a chemical facility in the Central U.S.

The objectives of the demonstration was to determine system removal efficiency (SRE) rather than destruction and removal efficiency (DRE) due to the lack of combustion, and to perform a PFAS material balance around the unit. The SRE % was based on the analysis of PFAS in the solid material and the sampling and analysis of PFAS in the stack gas.

Challenge

One of the biggest sampling challenges of the demonstration was to prevent PFAS contamination of the stack gas samples from sources such as the spiked feed material by using best practices detailed in a Montrose standard operating procedure (SOP) for sampling PFAS in stack gas based on EPA OTM-45. Another challenge was using EPA Method 1A to measure stack gas flow rate due to the small stack diameter (<12 inches).

Concentrations in the feed materials and the total mass of the feed material treated were used in SRE PFAS calculations. Montrose developed a spreadsheet that calculates the total mass of PFAS being treated then based that result against the total mass of PFAS in the stack gas to calculate the SRE.

The biggest analytical challenge for EAL was the analyses of the feed material and various process streams due to the complex sample matrices that AFFF can present that can potentially cause elevated detection limits. EAL’s experience in developing methodology and a SOP for analyzing AFFF-containing materials was critical to the objectives of the demonstration.

Solution/Results

The testing and lab analysis performed by Montrose and EAL, respectively, were extremely successful in accurately providing low level detection limits with minimal background effects to meet the objectives of the demonstration.

• SRE was comparable to combustion industry DRE standards
• The overall material balance of the spiked AFFF PFAS compounds was acceptable at >70%
• The collected stack gas blank samples (including field blank) were very clean

Conclusion

Both the Montrose PFAS sampling SOP and the EAL analytical SOP were influential in the success of the demonstration primarily focusing on best practices to prevent background contamination that would have compromised the integrity of the actual results and elevated the detection limits in both process and stack gas samples.