Citation:

Thoma, E., Alireza Gitipour, I. George, P. Kariher, M. MacDonald, G. Queiroz, P. Deshmukh, J. Childers, T. Rodak, AND V. Schmid. Assessment of Chemical Facility Ethylene Oxide Emissions Using Mobile and Multipoint Monitoring. Atmospheric Environment: X. Elsevier B.V., Amsterdam, Netherlands, 18:NA, (2023). https://doi.org/10.1016/j.aeaoa.2023.100214

Impact/Purpose:

This paper describes the results of a four-day next generation emission measurement (NGEM) demonstration study conducted at a midwestern U.S. chemical facility that uses ethylene oxide (EtO), a hazardous air pollutant, in the production of industrial surfactants. This study represents the first ever field trial of Geospatial Measurement of Air Pollution (GMAP) mobile mapping surveys for EtO. It also was the first demonstration of multipoint EtO measurements inside a chemical facility process unit by EPA. Additionally, the project demonstrated near-source canister grab sampling with TO-15 analysis as a way to provide quality assurance comparisons for the the new spectroscopic NGEM instrumentation utilized. This study achieved the goals of improving information on potential EtO emission sources in the facility while advancing NGEM method development through real world application. This project was a collaboration between EPA's Office of Research and Development (ORD), Center for Emissions Measurements and Modeling (CEMM) and EPA Region 7 under a Regional Applied Research Effort (RARE). It is noted that this effort enabled EtO GMAP technology transfer to other parts of EPA in 2022 for use as part of the EPA Administrators Journey to Justice Tour.

Description:

This paper describes the results of a four-day next generation emission measurement (NGEM) demonstration study conducted at a midwestern U.S. chemical facility that uses ethylene oxide (EtO), a hazardous air pollutant, in the production of industrial surfactants. The abstract for the paper follows. Abstract: Ethylene oxide (EtO) is a hazardous air pollutant that can be emitted from a variety of difficult to measure industrial sources, such as fugitive leaks, wastewater handling, and episodic releases. Emerging next generation emission measurement (NGEM) approaches capable of time-resolved, low part per billion by volume (ppbv) method detection limits (MDLs) can help facilities understand and reduce EtO and other air pollutant emissions from these sources yielding a range of environmental benefits. In October 2021, a 4-day NGEM method study was conducted at an EtO chemical facility in the midwestern United States (U.S.) Using analytical instruments based on cavity ring-down spectroscopy (CRDS), a combination of mobile surveys and stationary multipoint process unit monitoring assessed EtO concentrations in and near facility operations. Episodic EtO emissions from supply railcar switchovers and batch reactor washouts, lasting seconds to minutes in duration, produced EtO concentrations exceeding 500 ppbv inside the process unit in some cases. In one instance, EtO at ~30 ppbv was briefly observed hundreds of meters from the process unit. Lower level but more sustained EtO concentrations were observed near an EtO transfer pump and wastewater tank outfall and drain system. Overall, 4.6% of mobile survey data were above the 1.2 ppbv MDL while the nine multipoint test sampling locations ranged from 0.4% to 51% of data above the 5.0 ppbv operational MDL. In addition to improved understanding of EtO emissions in this facility, this paper describes advancements in method development for these new emissions assessment approaches.  

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