Coal-Fired Power Plant Wastewater Contributions to Bromide Concentrations in Drinking Water Sources

2019-01-18T21:36:23Z (GMT) by Kelly Good
Drinking water sources are affected by natural and anthropogenic processes that can alter their<br>treatability. Fossil fuel extraction and utilization activities have received considerable attention<br>recently since discharge of their associated wastewaters can increase bromide loading to source<br>waters and elevate bromide concentrations at downstream drinking water intakes. When bromide<br>is present in drinking water sources, the rate and extent of disinfection byproduct (DBP) formation<br>increases, and the speciation shifts toward brominated forms. Brominated DBPs exhibit higher<br>toxicity and are associated with negative health outcomes (e.g., cancer) at lower concentrations<br>than chlorinated DBPs. Thus, increases in brominated DBPs increase the health risk associated<br>with treated drinking water.<br>The objective of this work was to evaluate anthropogenic sources of bromide to surface waters and<br>their effects on drinking water sources, with a focus on coal-fired power plants operating wet flue<br>gas desulfurization (FGD) systems. Three main conclusions were reached through watershed-,<br>state-, and national-level analyses. First, bromide concentrations at a drinking water intake in the<br>lower Allegheny River in southwestern Pennsylvania are significantly affected by oil and gas<br>produced water and wet FGD discharges, particularly during low flow periods, and the<br>contributions are governed by the magnitude of the loads and the dilution capacity at the intake,<br>not geographic proximity. Power plant-associated loads could increase threefold if bromide<br>addition is selected as a process for mercury emission control. Second, considering a state-level analysis, there are significantly more people served by Pennsylvania drinking water systems that<br>are downstream of coal-fired power plant FGD discharges than previously identified, and multiple<br>power plants can affect a single drinking water intake. Third, although overall coal consumption<br>has declined, an increase in wet FGD-associated coal consumption, concurrent with increasing use<br>of halogen addition for meeting air quality regulations or securing federal tax credits, has resulted<br>in increases in bromide discharges from wet FGD that are affecting drinking water systems across<br>the country, particularly in the Ohio (HUC-05), Missouri (HUC-10) and South-Atlantic-Gulf<br>(HUC-03) hydrologic regions. Insufficient information on use of refined coal (which may or may<br>not have been treated with halogens) and on bromide addition for meeting mercury regulations<br>leads to significant uncertainty in the amount of bromide that will enter drinking water sources in<br>the future. <br>