Removal and emission characteristics of hazardous trace elements in total and graded particulate matters: A case study of a typical ultra-low emission coal-fired power plant

Particulate matters (PMs) and hazardous trace elements (HTEs) emitted from coal-fired power plants (CFPPs) have raised serious environmental and human issues. Herein, total PMs and graded PMs including PM<1, PM1-2.5 and PM2.5-10 at the inlet/outlet of air pollution control devices (APCDs) were collected from a representative ultra-low emission (ULE) CFPP in China. The removal efficiencies of total PMs by selective catalytic reduction (SCR), electrostatic precipitator (ESP), wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP) were 0.40 %, 99.9 %, 38.1 % and 85.3 %, respectively. PM2.5-10 was robustly removed by WFGD, while PM<1 and PM1-2.5 were readily removed by WESP. The removal efficiencies of As, Cd, Cr and Pb in total PMs by APCDs followed an order: ESP > WESP > WFGD > SCR. SCR significantly decreased Se concentration by 42.8 %, contrasting to the removal of As, Cd, Cr and Pb (10.8-20.8 %). As, Cd, Cr, Pb and Se concentrations in graded PMs at the outlets of ESP, WFGD and WESP decreased with particle size increasing. All As, Cd, Cr, and Pb contents in PM<1, PM1-2.5 and PM2.5-10 at WFGD outlet increased, surpassing their analogues at ESP and WESP outlets. However, the concentration of Se declined in PM<1 at WFGD outlet. The atmospheric emission factors (EFs) of As, Cd, Cr, Pb and Se in the studied ULE CFPP were respectively 7.32, 1.27, 6.05, 122.5 and 6.42 mg/t, in line with Monte Carlo simulations. This study would not only provide a basis for emission control of PMs and HTEs in CFPPs, but also promote the improvement of respective environmental policy.