Evaluation of density separation and other treatment methods for plastic media blasting (PMB) waste

The United States Air Force has developed plastic media blasting (PMB) to replace solvent paint stripping of its aircraft. This paint blasting operation generates a waste stream of mainly pulverized plastic, but the stream also contains enough paint pigments to make the PMB waste RCRA hazardous. A Phase I study identified density separation as the preferred treatment alternative to land disposal of the entire PMB waste stream in a hazardous landfill. This study found density separation to be a less attractive alternative to self-encapsulation, solidification/stabilization (S/S), and low-temperature ashing. Self-encapsulation resulted in a volume decrease but only moderate improvement in Toxicity Characteristic Leaching Procedure (TCLP) performance Solidification/Stabilization (S/S) into cementiaous waste for resulted in excellent TCLP performances, but volume increases. Low-temperature ashing resulted in dramatic volume decreases, but off-gas control is required to contain all the RCRA metals. The resulting ash must be stabilized (e.g., S/S) to meet TCLP limits.