Role of Refined Coal Use in Power Plant Effects on Downstream Drinking Water Quality

Abstract

Use of refined coal at power plants has been incentivized in tax law due to perceived benefits in control of criteria air pollutants. Refined coal use at power plants increased by 20% from 99 million metric tons in 2016 to 119 million metric tons in 2020. Additives in the refining process (e.g., halogens) can be present in power plant wastewater, especially where wet flue gas desulfurization (FGD) is utilized. Discharge of wastewaters containing halogens can have unintended negative effects on water quality at downstream drinking water plants. The increases in refined coal consumption over the past decade, and incomplete information on the nature and quantity of chemical additives used in refining, have increased uncertainty of the potential effects on drinking water. Considering 2020, the total bromide load associated with discharge of wet FGD wastewater generated from use of refined coal is estimated to range from 470 thousand kg/day to 12,900 thousand kg/day. While tax credits expired in 2021, additive use may continue to manage air pollutants; use of additives is not reported. Additional information on halogen application rates is needed to improve estimates and enable assessment of the potential effects of this practice on downstream drinking water treatment facilities.