Testing Methodologies for Landfill Codisposal of Municipal and Industrial Wastes

The results of a two-year pilot-scale investigation on codisposal of an industrial metal treatment sludge with municipal refuse under the influence of leachate containment and recycle are used to reveal the environmental consequences of heavy metals on such a landfill management practice. Comparisons between landfill simulators with and without varying metal sludge admixtures have provided an opportunity for examination of selected testing methodologies and parameters descriptive of inherent physical-chemical and microbially mediated reactions prevailing throughout the progress of landfill stabilization. Collectively, these analyses were sufficient to determine landfill assimilative capacity in terms of several controlling mechanisms including: potential inhibition of waste stabilization by mobilized heavy metals; precipitation, immobilization, and detoxification of heavy metals by entrapment and filtration; encapsulation and isolation of heavy metals by reaction with carbonates and sulfides; and formation of less toxic metal complexes with humiclike substances and potential for remobilization without transport phase regulation. On the basis of these results, a method for the determination of sludge loadings and their effects at both present and future landfill codisposal sites could be proposed.