Determination of the Leaching Dynamics of Metals from Municipal Solid Waste Incinerator Fly Ash Using a Column Test

Abstract

The objective of this work was to study the dynamic leaching behavior of thirty-three elements in municipal solid waste incinerator fly ash using a column test employing double deionized water. Nearly all of the elements initially present in the leachate were found to leach quickly and then decrease to near constant concentrations after five pore volumes of water passed through the column. Of the eight elements subject to toxicity characteristic leaching procedure (TCLP) investigations, all except lead were found in concentrations below regulatory limits. After three pore volumes of water passed through the column, leachate lead concentrations were found to have diminished to TCLP permissible levels. Concerning Resource Conservation and Recovery Act (RCRA) Title D regulations pertaining to permissible landfill leachate production, lead concentrations were still found at levels above allowable limits after as many as 40 pore volumes of leachate production. INTRODUCTIONThe purpose of waste incineration is usually to reduce waste volumes, so that more waste can be disposed of in a finite volume. One effect of this process, however, is the concentration of metals for disposal, usually in a waste site not specifically designed for the unique characteristics of this type of metal-enriched ash. A concern is the potential leaching of metals from ash by water passing through the fill. A comparison of three recent studies that examined the leachate at municipal solid waste (MSW) ash monofills found that in several cases, the concentrations of heavy metals in landfill leachates exceeded the limits set forth by the Environmental Protection Agency toxicity characteristics leaching procedure (TCLP) test used to define hazardous wastes.

An Experimental and Analytical Approach to Understanding the Dynamic Leaching from Municipal Solid Waste Combustion Residue

“…Fruchter et al (1990) identify a number of solubility-controlling minerals from field-scale lysimeter tests, but do not consider physical transport processes that may govern or influence leachate quality. Similarly, Buccholz and Landsberger (1995) and Chichester and Landsberger (1996) quantify the release of some 50 elements in lab-scale sequential extraction procedures and column experiments, respectively.…”

Heavy Metals in Urban Soils of East St. Louis, IL Part II: Leaching Characteristics and Modeling

“…7 The columns were constructed from cast acrylic plastic to a height of 34.3 cm and an inside diameter of 8.89 cm. They were specially designed for downward flow while alleviating some of the problems that occur with these types of columns.…”

Effects of Soil on Trace Metal Leachability from Papermill Ashes and Sludge

“…This study employs column-leaching techniques in a laboratory setting to understand mobility and leachability of trace metals from papermill ashes and sludge. Although a column leaching study cannot completely simulate leaching under natural rainfall in the field, it is useful for evaluating the relative leachability of salts and metals in papermill residues (Buchholz and Landsberger, 1995;Camobreco et al, 1996;Chichester and Landsberger, 1996;Fleming et al, 1996). The laboratory leaching test was designed to investigate the mobility of environmentally sensitive trace metals (As, Cr, Cu, Pb, Se, and Zn) from papermill ashes and sludge, and the effects of different soil horizons on metal leachability from these papermill residues.…”