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Regulatory Information

Stop 07: Separation Processes

Highlighted Topic:  Ongoing Clean Air Act Regulatory Changes

Tour Stop 07

Distillation and separation equipment can create a wide range of air emissions.  On this stop of the tour we will illustrate how a unit operation will be affected by ongoing changes to the Clean Air Act.

The CAA is a complex law with thousands of pages of regulation.  It is also highly technical, with alot of technical specifications and details - as well as legal specifications and details.  In addition, the regulations are not static.  In fact, there is a 10-year push to issue source-based air toxics regulations. After amendments passed to the clean Air act in 1990, EPA has a schedule for identifying sources of the 188 Toxic air pollutants, and issuing technology-based emissions standards (MACT) for each source category.   So EPA has been releasing a series of these NESHAPS and MACT standards over the past several years, including the MON or Miscellaneous Organic NESHAPS.

For chemical facilities, this means continuing effort to evaluate and comply with these new standards, while keeping up with the old standards.  Thus facilities can be affected by multiple source standards - even a given source or unit process can be affected by multiple standards.   These include not only NESHAPS standards for air toxics but also new source performance standards (NSPS) for various pollutants (though there is less ongoing regulatory development here currently).

For example, for a distillation unit in the synthetic organic chemical sector, the following source-specific standards may all be applicable at the same time:

  • VOC Emissions from Distillation Operations (Part 60, Subpart NNN)
  • Equipment leaks of VOCs (Part 60, Subpart VV)
  • Equipment leaks of benzene (Part 61 Subpart J)
  • Equipment leaks of volatile HAPs (Part 61 Subpart V)
  • Hazardous organic NESHAPS (HON)(Part 63 Subpart F)
  • Hazardous organic NESHAPS from process vents (Part 63 Subpart G)


Each of these rules might have specific MACT control requirements as well as other requirements.  Integrating these various requirements is a major challenge of Clean Air Act compliance.

Other Regulatory Issues:

In addition to air emissions, distillation and separation equipment also are a likely source of hazardous waste (e.g., still bottoms) as wastewater, and so would also be regulated under RCRA and Clean Water Act.