Environmental Engineering Reference
In-Depth Information
FIGURE 5.6 Kinetic mixer for polyethylene microencapsulation process.
ranged from 11.1 for waste forms containing 30 dry wt% to 7.8 for waste forms
containing 70 dry wt% nitrate salt. 18
In laboratory treatability studies, a wide variety of hazardous and mixed wastes
have been treated by polyethylene microencapsulation including evaporator concen-
trates, incinerator ash, blowdown solution, carbonate and mixed salts, ion exchange
resins, sodium-bearing wastes, molten salt oxidation residuals, and sludges. Results
varied based on waste loading and toxic metal (see Table 5.1). For example, TCLP
leaching of lead was reduced by factors ranging from 750 to 500,000 to concentra-
tions well below the characteristic limit for lead (5 mg/L) and in seven of eight
studies was below the allowable concentrations for the Universal Treatment Stan-
dard, 0.75 mg/L. 29 Similar results were obtained for leaching of cadmium, chromium,
selenium, and arsenic. 29
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