A recycling and disposal technology for municipal solid waste incinerator (MSWI) fly ash using high temperature sintering process was evaluated in an industrial scale facility with daily disposal capacity of 100 t/d. The emission, mass balance and distribution characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) as well as heavy metals (HMs) were assessed during two test runs. The PCDD/Fs emission from stack varied in range of 0.019 to 0.025 ng I-TEQ /Nm3, below international standards. The PCDD/Fs in the sintered product was reduced to 0.002-0.008 μg I-TEQ/kg from 2.593 to 2.704 μg I- TEQ/kg of the original MSWI fly ash (Mix-FA). However high concentration of 14.3 μg I-TEQ/kg were found in the secondary fly ash (Sec-FA). Therefore, a large share of PCDD/Fs just desorbed from the ash and the destruction efficiency (DRE) for PCDD/Fs was only 8.9%. The distribution characteristics of investigated HMs were primarily dependent on the evaporative properties. The results of HMs leaching test for the sintered product were considerably below the Chinese legal limits. The HMs leaching toxicity test for Sec-FA indicated which is a hazardous waste presented high risk to the environment. The use of the sintered product as construction material need further assessment on its long term HMs leaching behavior.
Keywords: Fly ash; Heavy metals; Mass distribution; PCDD/Fs; Sintering.
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