Potential environmental risk of trace elements in fly ash and gypsum from ultra-low emission coal-fired power plants in China

The ultra-low emission retrofitting (ULE) in China's coal-fired power plants (CFPPs) enhances removal efficien-cies of trace elements, which may increase their contents in fly ash and gypsum. However, their potential envi-ronmental risks in these wastes have been scarcely evaluated. Experiments indicated that the trace elements in fly ash and gypsum accounted for approximately 92.9-98.2% of the total outputs. Most trace elements in these wastes existed mainly as mobile/leachable forms, except for the Hg in fly ash (residual form). We comprehen-sively evaluated the potential environmental risks of trace elements in fly ash and gypsum from ULE CFPPs in China using a modified risk assessment approach that integrates a trace element enrichment model for waste, and chemical speciation datasets. We found that nationally, trace elements in gypsum represented low levels of potential risk, even after ULE. However, the potential moderate environmental risk of fly ash has aroused at-tention because of trace element pollution, where Hg and Cd contributed the major risks. The relatively high risks from fly ash are mainly distributed in Guangxi, Hunan and Hebei provinces. The disposal of fly ash in these areas should be given special attention in the future. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The ultra-low emission retrofitting in China's coal-fired power plants enhances removal efficiencies of trace elements, but may increase their contents in fly ash and gypsum. While the potential environmental risks of trace elements in gypsum are low, there are moderate risks from fly ash, particularly in provinces like Guangxi, Hunan, and Hebei. Special attention should be given to the disposal of fly ash in these areas in the future.