Comparison of Laboratory Batch Methods and Large Columns for Evaluating Leachate from Monofilled Solid Wastes

Abstract

Analyte concentrations In aqueous leachates from polyethylene tanks filled with five different solid wastes were compared with those In extracts from five laboratory batch procedures. Solid wastes used In the study included: electroplating sludge, electric arc furnace dust, paint Incinerator ash, mine tailings, and municipal refuse incinerator ash. Batch extraction procedures used to extract the solid wastes Included: Monofilled Waste Extraction Procedure (MWEP), U.S. EPA Extraction Procedure (EP), Ham Procedure C (HAM-C), Acetate Buffer Extraction Procedure (ABEP), and Saturated Paste Procedure (PASTE). Analyte concentrations in leachate from the large columns were reproducible and characteristic of each solid waste. In most Instances, analytes In column leachate reached a peak concentration at a liquld-to-solid ratio of 1:1 followed by a gradual to rapid decrease with continued leaching. Analyte concentrations found In large column leachate were related qualitatively to those found In extracts from the batch procedures which used delonlzed water as the extraction medium (i.e., MWEP, HAM-C, and PASTE). Batch extraction procedures using leaching medium containing acetic acid (I.e., EP) or sodium acetate buffer (I.e., ABEP) generally did not reflect analyte concentrations In leachate from the large columns. These results suggest that batch extraction procedures using acetic acid or acetate buffer are less effective for assessing the teachability of monofilled wastes than extraction methods using delonlzed water as the extraction fluid. Implications Large columns of five different solid wastes were leached with deionized water. Analyte concentrations found in large column leachates were related qualitatively to those found in extracts from the batch procedures which used deionized water as the extraction medium (MWEP, HAM-C, and PASTE). Batch extraction procedures using leaching medium containing acetic acid (EP) or sodium acetate (ABEP) generally did not reflect analyte concentrations in the leachates from the large columns. The results from this study suggest that batch extraction procedures using acetic acid or sodium acetate buffer are less effective for assessing the leachability of monofilled wastes than extraction methods using deionized water as the extraction medium.

Evaluation of environmental compatibility of EAFD using different leaching standards

“…Because the solution is confined in the leaching flask, the equilibrium is attained, rendering the mobility of metals non representative under these conditions. According to Jackson [21], extraction methods using deionized water as extraction fluid are more representative from natural phenomena than procedures using acetic acid or acetate buffer. The introduction of an acid source, as in the test from USA (TCLP) or NBR10005, greatly overestimates the leaching potential of a waste.…”

Prospects for cleaning ash in the acidic effluent from bioleaching of sulfidic concentrates

“…Cadmium, 0.2 (15)-297 (22) mg/kg; chromium, 36 (8)-812 (17) mg/kg; mercury, from below 0.1 mg/kg (4,8,10,12,13,19,22,25,26) to 20 mg/kg (20); and lead, 18 (26)-8130 (18) mg/kg are environmentally ominous. Waste ashes are notoriously suspicious and ashes from used wood and stabilized ash qualities may release high amounts of these.…”

“…Leaching in HCl [21], HNO 3 [22] or acids derived from ample crops [23] is an alternative. More elaborate schemes, for metal recovery or analysis [22,[24][25][26], contain several acid leaching stages, with increasingly stronger acids [27,28], acid leaching followed by alkaline leaching [29] or acid leaching followed by chelation for Cr, Cu, Pb and Zn adsorption [30]. Cd, Cr, Hg, Pb and Zn are elements not (always) well handled by sulfuric acid leaching alone.…”

Leaching Dynamics Studies of Municipal Solid Waste Incinerator Ash

“…For assessing the leachability of monofilled wastes, extraction methods using deionized water as the extraction fluid are more representative than procedures using acetic acid or acetate buffer. 20 The rates at which metals leach from the ash particles are not addressed in the TCLP test. A series of water batch extractions were completed to determine leaching dynamics of metals from grab samples of fly, bottom, and combined MSWI ash.…”