For the foreseeable future, thermal oxidation remains the principal methodology whereby emissions of gaseous and particle-bound pollutants are minimized and heat is recovered. The combustion and incineration approach is primarily viable for dilute streams where selective recovery is difficult and economically infeasible. Proposed expenditures in this technology continue to be high (see Table 5.21.1).

Where wastes are well characterized and contain no chlorine, few problems are encountered. Thermal destruction is a mature technology. Future improvements include enhanced energy recovery, smaller sizes, and continuous monitors for compliance. The presence of chlorine and other hetero atoms that lead to corrosive products (e.g., HCl) impose constrains on the material choices, gas cleanup, and monitoring requirements. The chlorine level entering the unit should be closely controlled so that downstream cleanup is efficient. In some cases, monitoring for PICs, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), is required.

Flares will come under increasing scrutiny in the future, and performance improvements will be required. No routine methods are available to measure emissions from flares. PIC inventories are inadequate. However, in regions where flaring is common, VOC emissions are expected to impact the photochemical smog potential of the atmosphere; hence, these emissions must be described in more detail.

—Elmar R. Altwicker

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