Frequent Questions

What methodologies were used to establish emission standards in the October 2005 Final Hazardous Waste Combustor MACT Rule?

Where control of the feed of hazardous air pollutants (HAP) was feasible and technically assessable, we used a methodology that ranked sources by their ability to control HAP feed and their ability to control emissions of HAP that are fed to the combustion device (measured as system removal efficiency). This methodology thus assessed the efficiency of controlling both the HAP inputs to a hazardous waste combustion unit, and the efficiency of control of the unit's outputs. Feed control of HAP in raw material and fossil fuel was not feasible because of the uncontrollable variability of sources of raw material and fossil fuel and uncontrollable variability of HAP constituents and concentrations in those raw materials and fossil fuel. Consequently, in assessing the contribution of HAP emissions from raw materials and fossil fuels, we assessed only the control of sources' outputs.

This methodology selected the best performing sources (and for new sources, the single best performing source) and assessed their level of performance. This methodology accounted for variability in emissions levels occurring from test to test, even by the best performing sources.

For more information, visit the hazardous waste combustion web page.

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