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Behavior and fate of As, Se, and Cd in an ultra-low emission coal-fired power plant

Author:
Chang, Lin, Yang, Jianping, Zhao, Yongchun, Liu, Huan, Zhang, Junying, Zheng, Chuguang
Source:
Journal of cleaner production 2019 v.209 pp. 722-730
ISSN:
0959-6526
Subject:
air pollution control, arsenic, bottom ash, cadmium, coal, environmental policy, equipment, flue gas desulfurization, fly ash, gypsum, liquids, power plants, recycling, selenium, slurries, water treatment
Abstract:
Environmental concerns regarding the toxicity of trace elements (TEs) and the harmful effects of these elements on humans have attracted worldwide attention. To meet stricter environmental policies, some coal-fired power plants have installed ultra-low emission equipment. In this paper, the behavior and fate of the trace elements As, Se, and Cd originating in an ultra-low emission coal-fired power plant equipped with air pollution control devices (APCDs), including selective catalytic reduction (SCR) equipment, a low-temperature economizer (LTE), an electrostatic precipitator (ESP), a wet flue gas desulfurization (WFGD) system, and a wet electrostatic precipitator (WESP), were investigated. Onsite samples of the feed coal, bottom ash, fly ash, gypsum, desulfurization slurry, WFGD effluent, WFGD-treated water, and WESP effluent were systematically collected and analyzed. The SCR and LTE configurations achieved a partial removal of As, Se, and Cd. The ESP trapped virtually all the particles and had a synergistic effect on the removal of the TEs. A systematic study of the recycling of the desulfurization slurry revealed TE enrichment in the WFGD system; because it concentrated in the liquid fraction of the gypsum slurry, Se was particularly susceptible to this enrichment. The effluent water treatment system achieved TE removal with efficiencies exceeding 94%. WESP operation achieved extensive removal of TE-enriched particles with percentages greater than 90%. The overall efficiencies of As, Se, and Cd removal obtained by the APCD system as a whole were 95.94%, 98.22%, and 92.70%, respectively.
Agid:
6217364