Characterization of polychlorinated naphthalenes (PCNs) emissions from metallurgical processes and municipal waste incinerators

• Main Authors: Nguyen Duy Dat, 阮維達
• Other Authors: Moo Been Chang
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/39s8w4

博士 === 國立中央大學 === 環境工程研究所 === 107 === Polychlorinated naphthalenes (PCNs) are ubiquitous in environment and have been receiving much public concern due to the adverse effects on human health and environment. However, study on PCNs has never been conducted in Taiwan in which high potential impacts of these compounds are anticipated. As the first study on PCNs in Taiwan, this study aims to characterize the occurrences of PCNs in ambient air collected from three different sites in northern Taiwan and emissions of PCNs from typical sources including two municipal waste incinerators (MWIs) and two secondary copper smelting (SCS) plants. Results indicate that higher level of PCNs is found at industrial (ID) site compared with those collected from urban (UB) and rural (RR) sites. Concentrations of ambient PCNs are higher in summer compared with those measured in winter for all three sampling sites. Homologue distribution of PCNs measured at ID site is different from two other sites for both gas and particulate phases, suggesting that different sources contribute to PCNs collected at ID site and other sites. Results of the logKp-logPL relationship indicate that both adsorption and absorption govern gas/particle partitioning of atmospheric PCNs. Emission factors of PCNs from SCSs are higher than those observed for MWIs. Minor contributions of dioxin-like PCNs to total TEQ concentration are found for flue gas (1-3%) and fly ash (0.3%). Performances of different air pollution control devices (APCDs) reveal that ACI+BH and SCR are effective for removal of PCNs from flue gas with the removal efficiencies ranging from 94.3 to 98%. Removal efficiency of PCNs achieved with ACI+BH and SCR increases as the chlorination level increases although different mechanisms govern the removal of PCNs in SCR and SDA+ACI+BH. The results suggest that dechlorination in SCR or reformation of low chlorinated homologues might occur within or after SCR, respectively. Increments of PCN concentration and chlorination level of PCNs in flue gas passing through ESP indicate that PCNs are formed in ESP via chlorination mechanism. Significant decrease of temperature in SDA plays an important role in PCN removal due to the transfer of PCNs from gas phase to particulate phase. The diagnostic ratios are firstly proposed and employed in this study for identifying potential sources of PCNs in ambient air. Thermal processes are identified as major sources of PCNs at ID site. PCNs collected at UB and RR sites are mixed sources of thermal emissions and evaporation, however, more influence of thermal sources in winter and more impact of evaporation sources in summer are observed. PCA results indicate that PCNs in some ambient air samples collected are originated from MWIs and SCSs investigated, while PCNs in other samples are emitted from other thermal sources and evaporation from technical mixtures. The results obtained in this study are important for understanding the characteristics of PCNs including (1) level, potential sources and gas/particle partitioning of PCNs in ambient air; (2) emission factors, performances of different APCDs and appropriate operating parameters for effective removal of PCNs in typical sources.