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Solid residues from municipal solid waste incineration (MSWI) can be categorized as air pollution control residues (AR) and bottom ash (BA). Both categories pose a particular environmental threat on account of the risk of the release of dioxins and metals. In Japan, handling of MSWI residues is of major concern and the treatment of AR prior to land®lling is stipulated. Accepted treatment techniques are melting, cementitious S/S (stabilization and solidi®cation), stabilization with a chemical agent and acid extraction. These methods are reviewed and evaluated in this paper with respect to: quality; quantity and utilization of end products; treatment costs; energy demand and process reliability. Thermal processes are superior regarding dioxin removal as well as material recovery and reuse, but treatment costs can be as high as 60 000 ¥ t -1 , i.e. one order of magnitude higher than for other processes. Cementitious S/S and chemical stabilization are characterized by the ease of operation, but the solid waste mass is increased by up to 40 and 10 wt.-%, respectively. Acid extraction is a proven and reliable technique and is inexpensive: nevertheless, it has the smallest share of the market.

Increasing amounts of municipal solid waste incineration (MSWI) residues are treated prior to landfilling or reuse. In Japan, electric arc melting is used for bottom ash vitrification that generates a glasslike slag. The objective of this paper was to assess this pretreatment technique with respect to its effect on metal mobility and metal content. Both bottom ash and slag were sampled and analyzed on total solids (TS), fixed solids (FS), particle density (pp), specific BET surface area, particle size distribution, and total element content. A six-step wet sequential extraction procedure was used for assessing metal mobility. The results were qualitatively verified by scanning electron microscopy. The major conclusion was that the availability of various metals was affected differently by electric arc vitrification. Metals were solidified, stabilized, and/or separated from the slag. The mobility of Cr, Cu, Zn, Pb, and Ca was reduced. In slag, majorfractions of these elements were found in moderately reducible phases or in the residual slag lattice. The approximately three-fourths of Pb [174 +/- 7 mg (kg of FS)-1] and half of Zn content [676 +/- 352 mg (kg of FS)-1] were most likely removed from bottom ash through evaporation. The total content increases of Al, Cr, Ni, and Cd (51 +/- 3, 621 +/- 27, 138 +/- 19, and 99 +/- 32%, respectively) were probably caused by the wear of furnace refractories.

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Solid residues from municipal solid waste incineration (MSWI) can be categorized as air pollution control residues (AR) and bottom ash (BA). Both categories pose a particular environmental threat on account of the risk of the release of dioxins and metals. In Japan, handling of MSWI residues is of major concern and the treatment of AR prior to landfilling is stipulated. Accepted treatment techniques are melting, cementitious S/S (stabilization and solidification), stabilization with a chemical agent and acid extraction. These methods are reviewed and evaluated in this paper with respect to: quality; quantity and utilization of end products; treatment costs; energy demand and process reliability. Thermal processes are superior regarding dioxin removal as well as material recovery and reuse, but treatment costs can be as high as 60 000 ¥ t -1 , i.e. one order of magnitude higher than for other processes. Cementitious S/S and chemical stabilization are characterized by the ease of operation, but the solid waste mass is increased by up to 40 and 10 wt.-%, respectively. Acid extraction is a proven and reliable technique and is inexpensive: nevertheless, it has the smallest share of the market.

Column percolation tests may be suitable for prediction of chemical leaching from soil and soil materials. However, compared with batch leaching tests, they are time-consuming. It is therefore important to investigate ways to shorten the tests without affecting the quality of results. In this study, we evaluate the feasibility of decreasing testing time by increasing flow rate and decreasing equilibration time compared to the conditions specified in ISO/TS 21268-3, with equilibration periods of 48h and flow rate of 12mL/h. We tested three equilibration periods (0, 12-16, and 48h) and two flow rates (12 and 36mL/h) on four different soils and compared the inorganic constituent releases. For soils A and D, we observed similar values for all conditions except for the 0h-36mL/h case. For soil B, we observed no appreciable differences between the tested conditions, while for soil C there were no consistent trends probably due to the difference in ongoing oxidation reactions between soil samples. These results suggest that column percolation tests can be shortened from 20 to 30days to 7-9days by decreasing the equilibration time to 12-16h and increasing the flow rate to 36mL/h for inorganic substances.

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