Abstract
Heavy metal removal from municipal solid waste incineration bottom ash using organic and inorganic ligands was investigated. Metal mobilization through the complexation with these ligands was evaluated by its leachability based on Japan leaching test 46. 0.02 mol-N/L of ammonium nitrate, sulfate, acetate, oxalate and citrate solutions with/without 0.02 mol-N/L urea were examined. In all cases, pH of the leachates were within the range from 10.4 to 11.0. Ammonium citrate promoted the leachabilityof Cu, Cr, Mn, P, and Fe. Especially, Fe leachability was increased more than 14 times. Ammonium nitrate accelerated only Mg leachability. Other inorganic and organic ligands showed no significant effect on metal mobilization. Under the condition that ammonium oxalate and citrate were co-existed, mobilization of Cu, Cr, Mn, P, and Fe were prohibited compared to those under the condition that only ammonium oxalate or citrate was used. Although urea itself showed no promotive effect on the leachability for most of metals, it accelerated the complexation of Cu, Cr, Mg, Mn, P and Fe with ammonium citrate or nitrate. Correlation analysis of leaching test results indicated strong relationship among Cr, Cu, P. and Mn. Fe and Mn also showed high correlation. This implies the decomposition of minerals that consisted mainly of these elements and it was supported partially by XRD analysis.
