Reduced Utilization Process Leaching Toxicity by Stabilizing Heavy Metals in Fly Ash from MSW Incineration Based on Hydrothermal Oxidation.

Hydrothermal oxidation is an effective approach to reduce leaching toxicity of fly ash from municipal solid waste incineration during utilization process. Herein, the effects of temperature, time, pH and Ce-Mn catalyst dosage on the stabilization of heavy metals in fly ash during hydrothermal oxidation were studied. The temperature of hydrothermal oxidation was positively correlated to the stabilization effect. However, the reaction time and pH emerged unstable effect. The amount of Ce-Mn catalyst had a slightly positive effect on the stabilizing at low doses, but it can be inhibited by excessive dose. The leaching concentrations of all heavy metals accorded with National Wastewater Discharge Standard of China (GB 8978-1996) under the optimal parameters, especially for Pb, Ni and Cu. The heavy metals were transformed from unstable fractions to residue fractions during hydrothermal process, among which the proportion of Cu and Zn residue fractions significantly increased and further reduced leaching toxicity.