STP760

    Modified Leach Test Incorporating an Elutriation Step for the Evaluation of Metal Sludges

    Published: Jan 1981


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    Abstract

    This study is limited to the evaluation of the toxic metal released from metal finishing sludges, combustion ashes, and the solid residuals from atmospheric dust collection systems in a landfill. When leach testing these wastes to establish the potential magnitude of the leachable metals, it has been found that the solid waste also usually contains readily soluble inorganic salts that could affect the leach results. The sludge cake usually contains only interstitial water. Evidently, the volume of the residual water and its salt content is a relatively small quantity. Slurries contain considerably more water, but the total salt content is still most often insignificant. The mix can be quite different if the treatment preceding the solids removal has utilized high-temperature processes, or has aimed to separate the solids by partial or total evaporation of the water. The ashes from combustion or the dust collected from atmospheric separation may not have been subjected to a water quench or washing; therefore, the soluble salts never have been separated. Depending on the volume of these salts when deposited in a landfill, they could by themselves cause a significant deterioration of the groundwater, surface waters, or the land. Therefore, a leach test method that would also reveal abnormal salt concentrations in the waste could fulfill an additional important function.

    Washing the solids with water will remove most of these easily soluble solids from the waste, leading to a more dependable and repeatable test condition for a subsequent leach test. The wash waters, if separately collected and tested, will provide insight into the magnitude of the soluble salt content of the solids. Following this logic, a distinction can be made regarding the short-term leach results (wash water) and subsequently, based on a 24-h leach test, the long-term leachability of the solids.

    Keywords:

    solid waste, extraction test procedures, metal sludges, water leach test, hazardous waste disposal


    Author Information:

    Penland, JL
    Manager, process engineering, vice president/general manager, and honorary president, ERC/Lancy, Zelienople, Pa.

    Steward, FA
    Manager, process engineering, vice president/general manager, and honorary president, ERC/Lancy, Zelienople, Pa.

    Lancy, LE
    Manager, process engineering, vice president/general manager, and honorary president, ERC/Lancy, Zelienople, Pa.


    Paper ID: STP28836S

    Committee/Subcommittee: D34.01

    DOI: 10.1520/STP28836S


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