Comparison of the efficiency of metal recovery from wet- and dry-discharged municipal solid waste incineration bottom ash by air table sorting and milling.

Separating high-density fractions from municipal solid waste incineration bottom ash (BA) is a promising approach for collecting metal resources and harmful elements. Herein, the efficiency of the recovery of metals (Cu, Zn, Au, Ag, and Pb) in the high-density fractions of two air-dried BAs discharged from wet-based systems (WBA), was compared with that of two BAs discharged from dry-based systems (DBA). WBAs and DBAs (<8 mm) were sorted using sieving, magnetic separation, milling, and air table sorting techniques.

Effective immobilization of geogenic As and Pb in excavated marine sedimentary material by magnesia under wet-dry cycle, freeze-thaw cycle, and anaerobic exposure scenarios.

Massive amounts of marine sedimentary materials with geogenic heavy metal(loids) are excavated by the subsurface construction projects and then exposed to weathering conditions, which pose potential threats to the environment. In the present study, 2 % magnesia (MgO) was applied to immobilize geogenic arsenic (As) and lead (Pb) in excavated marine sedimentary material. To better evaluate the immobilization efficiency under different environmental scenarios, the untreated and amended solids were subjected to wet-dry cycles, freeze-thaw cycles, and anaerobic incubation until 49 days.

The effects of redox conditions on arsenic re-release from excavated marine sedimentary rock with naturally suppressed arsenic release.

Massive quantities of marine sedimentary rock are excavated from urban coastal areas. The excavated rock often releases arsenic with concurrent oxidation of framboidal pyrite, but the arsenic release is naturally suppressed with subsequent atmospheric exposure. The present study evaluated the re-release of arsenic from excavated rock in which arsenic release has been naturally suppressed by the atmospheric exposure in the presence of sulfate ions under various redox conditions using the biological reduction method.

Impact of diatomite addition on lead immobilization in air pollution control residues from a municipal solid waste incinerator.

Air pollution control (APC) residues, which are known to be the byproducts of incineration treatment, exhibit a high leaching potential of toxic metals. Calcium silicate hydrate (C-S-H), which is a major hydration product of hardened cement and immobilizes toxic metal, can be formed by the reaction of Ca with pozzolanic Si in a highly alkaline environment. Toxic metals might be immobilized by the addition of pozzolanic material to APC residues (instead of using cement), which is a Ca source and provides an alkaline condition.

Determining Adsorption Parameters of Potentially Contaminant-Releasing Materials Using Batch Tests with Differing Liquid-Solid Ratios.

Adsorption parameters such as the distribution coefficient are required to predict the release behavior of contaminants using advection-dispersion models. However, for potentially contaminant-releasing materials (PCMs) such as dredged sludge and coal ash, these parameters cannot be obtained by conventional adsorption tests. This study developed a method to determine adsorption parameters for PCMs from a set of batch tests conducted in parallel as a function of the liquid-solid ratio (LS-parallel test).