Good KD, Vanbriesen JM. Power plant bromide discharges and downstream drinking water systems in Pennsylvania. Environmental science and technology. 2017 Sep 25. doi: 10.1021/acs.est.7b03003.
Coal-fired power plants operating wet flue gas desulfurization (FGD) have recently been implicated in increasing bromide levels in drinking water sources, which affect formation of disinfection by-products. Bromide was not included as a regulated constituent in the recent steam electric effluent limitations guidelines and standards (ELGs) since the U.S. EPA analysis suggested few drinking water facilities would be affected by bromide discharges from power plants. The present analysis uses a watershed approach to identify Pennsylvania drinking water intakes downstream of wet FGD discharges and considers the population served by these systems, providing context for the potential extent of the effects of coal-fired power plant discharges on downstream drinking water plants and consumers of publicly-supplied drinking water. Twenty-two (22) public drinking water systems serving 2.5 million people were identified as being downstream of at least one wet FGD discharge. During mean August flow conditions in receiving rivers, the median bromide concentration contributions at intake locations ranged from 5.2 to 62 µg/L for the Base scenario (including only natural bromide in coal) and 16 to 190 µg/L for the Bromide Addition scenario (natural plus added bromide for mercury control); ranges depend on bromide loads and receiving stream dilution capacity.
As in past studies such as this the assumptions made in this work drive the conclusions. Whether the results correspond to reality is a matter of speculation.
Regli S, Chen J, Messner M, Elovitz MS, Letkiewicz F, Pegram R, Pepping TJ, Richardson S, Wright JM. Estimating Potential Increased Bladder Cancer Risk Due to Increased Bromide Concentrations in Sources of Disinfected Drinking Waters. Environ Sci Technol. 2015 Oct 21.
Public water systems are increasingly facing higher bromide levels in their source waters from anthropogenic contamination through coal-fired power plants, conventional oil and gas extraction, textile mills, and hydraulic fracturing. Climate change is likely to exacerbate this in coming years. We estimate bladder cancer risk from potential increased bromide levels in source waters of disinfecting public drinking water systems in the United States. Bladder cancer is the health endpoint used by the United States Environmental Protection Agency (EPA) in its benefits analysis for regulating disinfection byproducts in drinking water. We use estimated increases in the mass of the four regulated trihalomethanes (THM4) concentrations (due to increased bromide incorporation) as the surrogate disinfection byproduct (DBP) occurrence metric for informing potential bladder cancer risk. We estimate potential increased excess lifetime bladder cancer risk as a function of increased source water bromide levels. Results based on data from 201 drinking water treatment plants indicate that a bromide increase of 50 µg/L could result in a potential increase of between 10-3 to 10-4 excess lifetime bladder cancer risk in roughly 90% of these plants.
Attempting to remove bromide from source waters may not prove to be the best approach for controlling halogenated DBP formation.
Tan J, Allard S, Gruchlik Y, McDonald S, Joll CA, Heitz A. Impact of bromide on halogen incorporation into organic moieties in chlorinated drinking water treatment and distribution systems. The Science of the Total Environment. 2015 Oct 17;541:1572-1580. doi: 10.1016/j.scitotenv.2015.10.043.
The impact of elevated bromide concentrations (399 to 750μg/L) on the formation of halogenated disinfection by-products (DBPs), namely trihalomethanes, haloacetic acids, haloacetonitriles, and adsorbable organic halogen (AOX), in two drinking water systems was investigated. Bromine was the main halogen incorporated into all of the DBP classes and into organic carbon, even though chlorine was present in large excess to maintain a disinfectant residual. Due to the higher reactivity of bromine compared to chlorine, brominated DBPs were rapidly formed, followed by a slower increase in chlorinated DBPs. Higher bromine substitution and incorporation factors for individual DBP classes were observed for the chlorinated water from the groundwater source (lower concentration of dissolved organic carbon (DOC)), which contained a higher concentration of bromide, than for the surface water source (higher DOC). The molar distribution of adsorbable organic bromine to chlorine (AOBr/AOCl) for AOX in the groundwater distribution system was 1.5:1 and almost 1:1 for the surface water system. The measured (regulated) DBPs only accounted for 16 to 33% of the total organic halogen, demonstrating that AOX measurements are essential to provide a full understanding of the formation of halogenated DBPs in drinking waters. In addition, the study demonstrated that a significant proportion (up to 94%) of the bromide in source waters can be converted AOBr. An evaluation of AOBr and AOCl through a second groundwater treatment plant that uses conventional treatment processes for DOC removal produced 70% of AOX as AOBr, with 69% of the initial source water bromide converted to AOBr. Exposure to organobromine compounds is suspected to result in greater adverse health consequences than their chlorinated analogues. Therefore, this study highlights the need for improved methods to selectively reduce the bromide content in source waters.