The U.S. EPA on Sept. 8 issued an advanced notice of proposed rulemaking (ANPRM) seeking public comments to assist in the potential development of regulations for pyrolysis and gasification units that are used to convert solid or semi-solid feedstocks into useful products, such as energy, fuels and chemical commodities.

The ANPRM explains that the agency is seeking comments and data to assist in the consideration of potential changes to existing regulations under Clean Air Act section 129 or the development of regulations pertaining to pyrolysis and gasification units used to produce useful products. Feedstocks addressed in the ANPRM include solid waste, including municipal solid waste (MSW), commercial and industrial waste, hospital/medical/infectious waste, sewage sludge, and other solid waste; biomass; plastics; tires; and organic contaminants in soils and oily sludges.

“As a result of recent market trends, especially with respect to plastics recycling, the EPA has received several inquiries about regulations under CAA section 129 for solid waste incineration units and the applicability of such regulations to pyrolysis and gasification units for a variety of process and feedstock types,” the EPA said in the ANPR. “Based on these requests and the differences in language pertaining to pyrolysis among the CAA section 129 rules, the agency believes that there is considerable confusion in the regulated community regarding the applicability of CAA section 129 to pyrolysis and gasification units.”

The EPA said it in August 2020 proposed various revisions to section 129 regulations for “other solid waste incineration units,” including a proposed proposal to remove the reference to “pyrolysis/combustion units.” In light of comments received on that proposal and ongoing questions about the regulation of pyrolysis and gasification units, the EPA has determined that issuance of the new ANPRM will help the agency gain a comprehensive understanding of these units to aid in potential development of future regulations or changes to existing CAA section 129 regulations pertaining to pyrolysis and gasification units.

According to the agency, the ANPRM provides EPA with an opportunity to gather information on the design, types, and sizes of pyrolysis and gasification units. It also allows the agency to identify other issues for consideration, including appropriate categorization of pyrolysis and gasification units.

The public comment period is open through Nov. 8. A full copy of the ANPRM is available on the Federal Register website.