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AN EVALUATION OF FACTORS AFFECTING THE SOLIDIFICATION/STABILIZATION OF HEAVY METAL SLUDGE
Citation:
Bricka, R. M. AND L. W. Jones. AN EVALUATION OF FACTORS AFFECTING THE SOLIDIFICATION/STABILIZATION OF HEAVY METAL SLUDGE. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-92/023, 1992.
Impact/Purpose:
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Description:
Solidification/stabilization (SIS) of hazardous waste involves mixing the waste with a binder material to enhance the physical properties of the waste and to immobilize contaminants that may be detrimental to the environment. Many hazardous wastes contain materials that are known to inhibit the setting and strength development properties of cement and pozzolan binding agents commonly used in S/S processes. The study summarizes the results of an evaluation of the effects of 10 interfering substances (oil, grease, lead, copper, zinc, sodium hydroxide, sodium sulfate, phenol, trichloroethylene, and hexachlorobenzene) on the physical and contaminant mobility properties of a solidified/stabilized heavy metal sludge. Three binder materials (Portland cement, CEM; lime/fly ash, LFA; and cement/fly ash, CFA) were used to solidify/stabilize a specially prepared sludge containing substantial concentrations of four metals (cadmium, chromium, nickel, and mercury). The effects of these interfering materials were evaluated using five physical tests (unconfined compressive strength, cone index, bulk density, wet/dry cycling, and permeability). Contaminant leaching properties were evaluated using the U.S. Environmental Protection Agency's (EPA) extraction procedure (EP) test. Microchemical/ micromorphological analyses were also performed on the samples. Test results indicated that copper, lead, zinc, grease, oil, and phenol have a significant detrimental effect on the physical properties of the solidified/stabilized sludge. In contrast, the effects of hexachlorobenzene, trichloroethylene, and sodium sulfate on the physical properties were much less significant. The EP leaching test indicated that contaminant leaching, except for mercury, was highly dependent on the extraction solution's final pH. No definitive conclusions could be drawn from the microchemical/micromorphological examinations. This research confirms the need for waste-binder specific studies before selecting a chemical S/S process for the treatment of hazardous waste.