Kocurek, Dianna S. (Tischler/Kocurek); Woodside, Gayle (IBM Corp.). The treatment of a particular hazardous waste often involves the integration of a number of unit processes to develop a comprehensive treatment system. This article gives a brief overview of the most common unit processes used for the treatment of hazardous wastes and discusses, as appropriate, how these unit processes are typically combined. Unit processes in this article are divided into three general categories: physical–chemical, biological, and thermal processes. Soil and ground water treatment technologies are presented as a fourth section and include only those technologies that are unique to these media or that are innovative or emerging technologies used most frequently with these media.
Physical–chemical processes include air stripping, carbon adsorption, chemical oxidation, dissolved air flotation, distillation, evaporation, ion exchange, membrane filtration, neutralization, oil–water separation, oxidation and reduction, precipitation, sedimentation–clarification, solvent extraction, stabilization–solidification, steam stripping, supercritical fluid extraction, supercritical water oxidation, and wet air oxidation. Biological treatment focuses on the biodegradability of different compounds and the most widely used technology for organic wastewaters, activated sludge. Thermal processes include catalytic oxidation, fluidized beds, liquid injection, multiple hearth furnaces, rotary kilns, and thermal desorption. Soil and ground water treatment technologies include bioremediation (
in situ
and
ex situ
), electrokinetics, in situ air stripping, pump and treat, soil flushing, soil leaching, soil vapor extraction, soil washing, and vitrification. Vol. 25, pp. 284–324, 79 references to August 1996.