Regenerative Thermal Oxidizers (RTOs) are used at WWTPs to control air pollution and odors (H2S, VOCs, and reduced sulfur compounds). RTOs heat exhausts to high temperatures, converting compounds into harmless substances, dramatically reducing odors for nearby communities. While there are no RTOs at WWTPs in the UK, regulations in the US require these devices. Their high destruction and reduction efficiencies (DRE) allow WWTPs to meet Clean Air Act requirements and state/local limits. RTOs recover heat from exhaust and preheat incoming air – resulting in low fuel use and continuous control in large, wet, highly variable airflows. They are commonly installed at headworks, influent channels, primary clarifiers, and solids handling areas. Compared to cheaper biofilters, RTOs can handle high H₂S spikes and cold weather; compared to activated carbon, RTOs are cost competitive at large scale.

Recent PFAS regulations and documented releases from aeration basins and biosolids handling processes (e.g., dryers and pyrolysis/gasification systems) prompt use of RTOs for addressing both odor and PFAS releases. This presentation provides data on PFAS release rates from full-scale WWTPs, sampling methods, and results of air emissions testing, which when considered with other objectives justify use of RTOs.