EPA Expresses Concern over the Release of Bromide from Power Plants On September 30th, 2015 the U.S. Environmental Protection Agency (EPA) issued the Steam Electric Power Generating Effluent Guidelines and Standards (40 CFR Part 423) covering wastewater discharges from power plants operating as utilities. In the preamble of this document, EPA noted that “depending on site-­‐specific conditions and applicable state water quality standards, it may be appropriate for permitting authorities to establish water quality-­‐
based effluent limitations on bromide, especially where steam electric power plants are located upstream from drinking water intakes.” This may require utilities to interact with multiple regulatory agencies to address local concerns with the discharge of bromide in plant effluent waters. The primary concern regarding the discharge of bromide to the aquatic environment is the potential for the generation of trihalomethanes (THM) and similar compounds that pose a significant health risk. (http://water.epa.gov/drink/contaminants/basicinformation/ disinfectionbyproducts.cfm). Major sources of bromide in coal-­‐fired power plants can be the use of brominated Powdered Activated Carbon (PAC) for mercury control or the addition of calcium bromide to the coal feed to promote oxidation of mercury in the flue gas for subsequent capture as a soluble mercury compound in the plant’s wet Flue Gas Desulfurization (FGD) scrubber system. Section 45 tax credit systems often employ bromide compounds as well. The EPA documented in the preamble several instances of issues caused by bromide in power utilities discharges. A 2014 research study conducted by McTigue et. al. concluded that four public drinking water facilities have experienced a significant increase in bromine levels as a direct result of the installation of wet FGDs at local power utilities (http://www2.epa.gov/eg/ steam-­‐electric-­‐power-­‐generating-­‐effluent-­‐guidelines-­‐2015-­‐final-­‐rule-­‐documents, p 239). In addition, there are thirty documented cases of ground water contamination from surface impoundments at power utilities (Final Rule, p 13). Any impoundments near drinking supply, including aquifers, are potentially subject to regulations. Regulators are also targeting leachate limits, as well. There are several alternatives for coal-­‐fired power plants to avoid the issue cited above. One is to implement a zero-­‐liquid discharge scheme for wastewater; even in this case, evaporation ponds must be designed and built to assure no groundwater contamination is possible, due to the high solubility of the bromide ion. Another is to implement a mercury control strategy that avoids the use of bromine. Novinda Corp.’s Amended Silicates family of mercury control reagents are all formulated WITHOUT BROMINE, offering options for mercury control that are simple, cost-­‐
effective, and that sequester captured mercury in the form of mercuric sulfide, a highly insoluble mercury compound. th
999 18 St., Suite 1755, North Tower, Denver, CO 80202 | tel 720.473.8320 | fax 720.473.8360 | www.novinda.com Bromine Pathways to Effluent Waters
Bromine compounds added to the feed coal for enhanced mercury oxidation downstream of the boiler appear as gas-­‐phase bromides in the combustion flue gas. They react with gas-­‐phase mercury to form oxidized mercury compounds, still in the gas phase. These are captured either on fly ash or more commonly in the wet FGD due to their high solubility. FGD effluent waters will contain bromide from these sources. Brominated PAC captures gas-­‐phase mercury via a sorption process on the carbon particles, which are removed from the flue gas in the plant particulate control equipment. Sluicing of the fly ash/PAC mixture will result in bromide being solubilized in the sluice water, and subsequent aqueous discharge after settling in an ash pond will introduce bromide into the effluent. Even landfilled fly ash can release bromide into landfill leachate waters. Figure 1. Bromine Pathways to Coal-­‐fired Power Plant Effluent Waters (source: EPA) http://www2.epa.gov/sites/production/files/2015-­‐05/steam-­‐electric-­‐key-­‐wastestreams_2025x1571.png Parties At-­‐Risk for Future Regulations Records show there are more than 100 FGD wastewater streams near public drinking water intake in North America. Any power utility applying for an NPDES permit must indicate the current levels of bromine in effluent streams. The permitting authority has the power to issue limits on a case-­‐by-­‐case basis. Plants wishing to meet the voluntary incentives program set-­‐forth in the EPA preamble will need to meet zero discharge of all regulated pollutants. To learn more about Novinda’s Bromine-­‐free mercury control options contact Jay Crilley at (724) 502-­‐0013