NACWA submitted initial comments to EPA on December 20, 2021 on the Agency’s Advanced Notice of Proposed Rulemaking to potentially develop regulations for pyrolysis and gasification units. Pyrolysis and gasification units are innovative technologies that are used to convert a variety of solid or semi-solid feedstocks to useful products including energy, fuel and other commercial products.

Common feedstocks supplied to gasification and pyrolysis units include municipal solid waste, plastics, industrial waste, and to some degree biosolids. Processing biosolids in a pyrolysis or gasification unit converts this feedstock to a renewable thermal energy (syngas) and a recycled beneficial product (biochar) that can be then land applied as a fertilizer, and this process shows promise as alternative management options for wastewater residuals. There are also early signs that these technologies can destroy PFAS although more research is needed.

While there are not many public clean water utilities looking to install and implement gasification or pyrolysis right now, NACWA is aware of a handful of utilities that do use these technologies. We are also aware of other utilities that are considering these as a management option, especially as local land application of biosolids and/or sewage sludge incineration units (SSIs) are becoming more challenging and cost-prohibitive due to various regulatory and emerging contaminant concerns.

NACWA’s comments reflect this reality and ask the Agency to consider the broader context in which the public clean water community must continue to operate with growing limited choices for biosolids management. As such, NACWA urges EPA not to place gasification or pyrolysis units into existing Clean Air Act categories.

Gasification and pyrolysis are inherently different processes than other thermal treatment because they do not combust any solid, semi-solid, or liquid material even though they employ heat. EPA itself has specifically determined, on at least three prior occasions, that gasification and pyrolysis units processing biosolids are not SSIs and therefore not subject to the CAA’s New Source Performance Standards that carry considerable regulatory compliance requirements.

NACWA’s comments also emphasize it is imperative that EPA’s Office of Air and Radiation work closely with the Office of Research and Development and Office of Water’s biosolids team on any future regulations that concern biosolids. The clean water community remembers clearly that this collaboration was severely lacking when regulations were initially developed for SSIs and that EPA failed to consider the unique feedstock and operating environments of these units. NACWA would like to see EPA working collaboratively across offices if a CAA proposal on pyrolysis and gasification moves forward.

NACWA looks forward to working with EPA as it reviews comments and with its members on what is ahead for these innovative technologies. Members with questions can contact Emily Remmel, NACWA’s Director of Regulatory Affairs.