Abstract: Se is released to gas phase and combines with fine particles in flue gas after coal combustion which can be captured by the wet desulfurization( WFGD) system and wet electrostatic precipitator( WESP) in flue gas,and it is important to determine the partitioning and species of Se in these systems.Based on hydride generation-atomic fluorescence spectrometry( HG-AFS),the partitioning and species of Se in the key locations of WFGD and WESP were studied.It is found that Se can be removed by WFGD system in flue gas.The concentration of Se in the solid fraction and liquid fraction of desulfurization tower slurry are 1.07 μg/g and 0.123 mg/L,respectively.Over 80% Se in the desulfurization tower is oxidized to Se( VI) under forced oxidation condition.After separated by a hydrocyclone,most Se is transported to effluent treatment process.The predominant Se species in the effluent treatment process is Se( VI),with the proportion exceeds 77%,which accounts for low efficiency in Se removal by traditional three-linked tank technique. Se exhibits a significant enrichment in solid fraction of the flush water from WESP whose concentration is 13.9 μg/g,while 0.001 6 mg/L Se is determined in the liquid fraction where proportions of Se( IV) and Se( VI) are 34.35% and 65.65%,respectively.WESP equipment achieves Se deep removal from flue gas,and transports this part of Se to the solid fraction of ash.It is calculated that with the help of WESP 2.9 kg/yr particle-bound Se is removed.