Multiple effects and emission characteristics of air pollution control devices on PCDD/Fs and PCBs from coal-fired...

China's coal-fired power plants (CFPPs) employ air pollution control devices (APCDs) to reduce pollutant emissions. However, the impacts of APCDs on congener-specific removal mechanisms, formation pathways, and emission characteristics of PCDD/Fs and PCBs remain insufficiently understood in CFPPs. This study investigated conventional APCDs, including electrostatic precipitators (ESP) and wet flue gas desulfurization (WFGD), and retrofitted APCDs incorporating low-low temperature ESP (LLT-ESP) and wet ESP (WESP) across six CFPPs and two industrial boilers. CFPPs with conventional APCDs exhibited higher stack concentration of PCDD/Fs and PCBs than those with retrofitted APCDs and industrial boilers (p < 0.05, Cohen's d > 0.8). LLT-ESP achieved the highest removal efficiencies of 99.0% and 88.2% for PCDD/Fs and PCBs, respectively, while WFGD and WESP showed moderate performance. Memory effects were observed in retrofitted WFGD. APCDs showed congener-specific removal, with highly chlorinated congeners preferentially adsorbed onto fly ash. The annual emissions of PCDD/Fs from flue gas and gypsum were 135.0 and 22.4 g TEQ, respectively, while those of PCBs were 4.6 and 0.3 g TEQ, respectively. Kernel density analysis indicated that eastern and central regions exhibited larger emissions due to the geographical distribution and emission density. of CFPPs. These findings improve our understanding of the impact of APCDs on dioxin-like pollutant mitigation. Environmental implications. This study analyzes the effects of APCDs on the removal mechanism and emission characteristics of PCDD/Fs and PCBs under operating conditions in CFPPs with different APCD configurations. This study shows that CFPPs with ultra-low emission APCDs exhibit lower emissions and higher removal efficiencies. The PCDD/Fs emission evaluation shows a 71% decrease in flue gas. There are significant spatial variations in emissions, which are associated with urban agglomerations. APCDs also alter congener distribution and formation pathway. High-chlorinated PCDD/Fs are easily adsorbed onto fly ash. These findings provide valuable insights for synergistic control of multiple pollutants in CFPPs.