PCDD/DFs and coplanar PCBs in fly ash samples from various types of incinerators in Taiwan

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co-PCBs) were determined in fly ash samples from municipal solid waste (MSW), medical waste (MW), and electricity power plant incinerators in Taiwan. The average concentrations of PCDD/DFs and Co-PCBs are 7.02 ng-TEQ/g and 1.06 ng-TEQ/g, respectively. The contributions to total TEQ are 24% from PCDDs, 64% from PCDFs, and 12% from Co-PCBs, indicating that PCDFs generate the highest environmental impact and MSW and MW incinerators are potential Co-PCBs contaminating sources. The levels of PCDD/DFs and Co-PCBs found in ash samples increase from petroleum-fired, coal-fired, large municipal solid waste, small medical waste, to small municipal solid waste incinerators, and are generally lower than those from incinerators built earlier. All fly ash samples analyzed in this study were considered hazardous materials. More research is suggested to establish the relationship between the amounts of PCDD/DFs and Co-PCBs in fly ash and in flue gas.