Source identification and quantification of chlorinated and brominated polycyclic aromatic hydrocarbons from cement kilns co-processing solid wastes.

Chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are widespread persistent organic pollutants (POPs) in environments. Identifying the new sources of Cl/Br-PAHs is important for implementing source control and reducing environmental risk. Although co-processing of solid wastes by cement kilns increased recently, the occurrences and characteristics of Cl/Br-PAHs as emerging POPs during cement kiln co-processing solid wastes have not been investigated. This study firstly investigated the occurrences, characteristics, and variations of Cl/Br-PAHs from four cement kilns co-processing different solid wastes. The concentration ranges of Cl-PAHs and Br-PAHs in stack gas samples from the investigated cement kilns were 15.6-94.1 ng m and 1.04-4.28 ng m, respectively. Emission factors of Cl-PAHs and Br-PAHs through stack gases were 29.9-275 μg t and 3.0-8.3 μg t, respectively. Variations of Cl/Br-PAHs in particle samples collected from different process stages within the cement kiln system indicated that the kiln end was the major formation zone for Cl/Br-PAHs. Congener profiles of Cl/Br-PAHs varied with the co-processed solid waste types, indicating the important influence of raw material compositions. Calculations of net emissions of Cl/Br-PAHs within the cement kiln systems suggested efficient destruction (87.6%-98.8%) of Cl/Br-PAHs by the cement kilns.