Characteristics of dioxins content in fly ash from municipal solid waste incinerators in China

• Fly ash was divided into four groups according to profile characteristics of dioxins.
• Low-chlorinated PCDD/F homologs were dominated in the fly ash.
• The concentration of 3,3′,4,4′-TePCB was highest among 12 dioxin-like PCBs.
• The main contribution to the TEQ was from 1,2,3,7,8,-PeCDD and 2,3,4,7,8-PeCDF.

MSWI fly ashes sampled from 15 large-scale commercial municipal solid waste incineration plants in China were analyzed for seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDFs) as well as twelve dioxin-like polychlorinated biphenyls (dl-PCBs). The concentration of PCDD/PCDFs and dl-PCBs in fly ash samples ranged from 2.8 to 190 ng g−1, and 59.6 ng g−1 on average. The toxic equivalent (TEQ) ranged from 34 to 2500 ng WHO(2005)-PCDD/PCDF-PCB-TEQ kg−1, and 790 ng WHO(2005)-PCDD/PCDF-PCB-TEQ kg−1 on average. For PCDDs, hexa-chlorinated homolog was the dominant compound except two fly ash samples. Tetra-chlorinated homolog was dominant for PCDFs except one sample. The ratio of PCDDs/PCDFs ranged from 0.32 to 2.44 (average 0.97). The contribution of dl-PCBs to total concentration and TEQ was relatively minimal. Correlation between the concentration of three congeners and total TEQ values of fly ashes was also established. The findings obtained in this work provided overview information on the PCDD/PCDF-PCB content characterization of MSWI fly ash in China, which can be available for MSWI fly ash management in the environment.