Reduction of PCDDs/PCDFs in MSWI fly ash using microwave peroxide oxidation in H2SO4/HNO3 solution

Abstract Microwave peroxide oxidation (MPO) is an energy-efficient and low GHG emission technology to destroy the hazardous organic compounds in solid waste. The objective of this paper is to explore the reduction feasibility of PCDDs/Fs in MSWI fly ash using the MPO in H 2 SO 4 /HNO 3 solution. Nearly all PCDDs/Fs, 99% in the original fly ash, can be reduced in 120 min at the temperature of 150 °C using the MPO treatment. It was also found that a change occurred in the content distribution profiles of 17 major PCDD/F congeners before and after MPO treatment. This provides the potential to reduce the actual PCDDs/Fs content more than I-TEQ contents of PCDDs/Fs. The percentile distribution profile has a tendency of higher chlorinated PCDDs/Fs moving to the lower ones. It concludes that a significant reduction efficiency of I-TEQ toxicity was achieved and showed sufficient reduction of toxic level to lower than 1.0 ng I-TEQ (g dw) −1 . The treatment temperature would be a critical factor facilitating the dissolution because higher temperature leads more inorganic salt (parts of fly ash) dissolution. Some problems caused by the MPO method are also delineated in this paper.