Estimation of Emissions of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans and Dioxin-Like Polychlorinated Biphenyls from Chinese Hot Dip Galvanizing Industries

Abstract

Hot dip galvanizing industry is considered an emission source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study investigated the emission factors and total emission amounts of PCDD/Fs and dioxin-like polychlorinated biphenyls (DL-PCBs) from ash and precipitate in Chinese hot dip galvanizing industry. Concentrations and toxicity equivalents (TEQs) of PCDD/Fs and DL-PCBs were determined. Due to the degreasing step that reduced the contents of organic materials and chlorine in Chinese hot dip galvanizing, the concentration of PCDD/Fs and DL-PCBs in the samples was not as high as expected. Mean WHO-TEQ of PCDD/Fs and DL-PCBs in samples was 15.7 pg g−1. Contributions of 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF, and CB-126 dominated the total TEQs. We estimated the emissions of PCDD/Fs from Chinese hot dip galvanizing industries using the solvent method. The mean emission factor for PCDD/Fs and DL-PCBs released to residue was 9.50 ng TEQ ton−1 of the product. The total emission amount of PCDD/Fs and DL-PCBs released to residue in the hot dip galvanizing industries using the solvent method was 280 mg WHO-TEQ year−1 in China. Results obtained in this study will be helpful for decision makers in prioritizing sources of PCDD/Fs.