Pyrolysis Treatment 1
Pyrolysis is formally defined as chemical decomposition induced in organic materials by heat in the absence of oxygen. In practice, it is not possible to achieve a completely oxygen-free atmosphere; actual pyrolytic systems are operated with less than stoichiometric quantities of oxygen. Because some oxygen will be present in any pyrolytic system, nominal oxidation will occur. If volatile or semivolatile materials are present in the waste, thermal desorption will also occur.
Pyrolysis is a thermal process that transforms hazardous organic materials into gaseous components and a solid residue (coke) containing fixed carbon and ash. Upon cooling, the gaseous components condense, leaving an oil/tar residue. Pyrolysis typically occurs at operating temperatures above 800°F [1, pp. 165, 167; 2, p. 5]. 2 This chapter does not address other thermal processes that operate at lower temperatures or those that operate at very high temperatures, such as a plasma arc. Pyrolysis is applicable to a wide range of organic wastes and is generally not used in treating wastes consisting primarily of inorganics and metals.
Pyrolysis should be considered an emerging technology. (An emerging technology is a technology for which performance data have not been evaluated according to methods approved by EPA and adhering to the EPA quality assurance/quality control standards, although the basic concepts of the process have been validated [3, pp. 1–2].) Performance data are currently available only from vendors. In addition, existing data are limited in scope and quantity, and are frequently of a proprietary nature.
This chapter provides information on the technology applicability, the types of residuals resulting from the use of the technology, the latest performance data, site requirements, the status of the technology, and where to go for further information.