September 20, Water Docket U.S. Environmental Protection Agency Mail Code: 4203M 1200 Pennsylvania Avenue, NW Washington, DC 20460

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1 September 20, 2013 Water Docket U.S. Environmental Protection Agency Mail Code: 4203M 1200 Pennsylvania Avenue, NW Washington, DC Attention: Docket ID Number: EPA HQ OW Re: Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category: Proposed Rule; 78 FR (June 7, 2013) The Institute of Clean Air Companies (ICAC) appreciates the opportunity to comment on the EPA's proposed Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category published June 7, ICAC is the national non-profit trade association of companies that supply air pollution control and monitoring systems, equipment, reagents, and services for stationary sources. ICAC has promoted the air pollution control industry and encouraged improvement of engineering and technical standards since Our members include over 90 companies who are leading manufacturers of products, equipment and services to control and monitor emissions of particulate matter (PM), volatile organic compounds (VOC), sulfur dioxide (SO2), nitrogen oxides (NOx), hazardous air pollutants (HAP), and greenhouse gases (GHG). General Comments ICAC member companies provide equipment for the control of certain components in air emissions from utility steam-electric plants; specific components controlled include NOx, SO 2, SO 3, HCl, and mercury. EPA has recognized that air pollution control devices (APCDs) can Page 1

2 generate wastewaters that contain significant quantities of metals (e.g., mercury, arsenic, and selenium). In the proposed Effluent Limitation Guidelines (ELG), EPA identified the applicable rules for air emissions, which will result in new APCDs installed at coal-fired utility power plants and, therefore, which will increase the discharge of metals in the plants wastewater. The decision about which air pollution control strategy to choose can be driven by concerns about impacts on water side of the plant, as recently when one power plant chose carbon injection over bromine addition to the fuel for mercury control in part because of concerns about how much mercury would be transferred to the wet FGD. 1 As another example of the interdependence of air and water control strategies, there is evidence that the use of halogen additives (e.g., bromine) for mercury control can shift some of the selenium captured from the particulate control device to the wet scrubber. 2 Selenium can be difficult to precipitate in the scrubber wastewater treatment system if it is mostly found as the highly soluble Se(VI) species in the scrubber liquor. This potential increase in Se in the scrubber discharge would require additional treatment. Some utilities will choose dry sorbent injection (DSI) to control emissions of HCl for compliance with the Mercury and Air Toxics Standards (MATS). A DSI system is the injection of dry alkaline sorbents directly into combustion flue gas and the subsequent collection of the sorbents, typically in the particulate control device or, less commonly, in the wet flue gas desulfurization scrubber. Dry sorbent injection sorbents can capture metals like selenium with the fly ash. 3 Whether the DSI reagent increases the capture of a specific gas phase metals or not, there are at least two new mechanisms that then impact the leachability of the metals present in the fly ash. 4 First, these alkaline sorbents increase the ph of the resulting fly ash when the latter is mixed with water, resulting in the potential for increased leaching of certain trace elements (Se, As). 3, 5 The change in ph may cause previously sequestered metals to mobilize. This might be an issue for ash ponds or impoundments at plants firing bituminous coal. For example, the addition of trona to bituminous coal ash has been shown to increase the ph of the fly ash from the range of 7 to 8 to more than Second, it should also be noted that since fly ash is a pozzolan, calcium DSI reagents have the potential to encapsulate many of these same metals since they trigger 1 Blythe, G.M.; Bissell, J.S.; Labatt, L.S. Optimization of Mercury Control on a New 800-MW PRB-Fired Power Plant. Paper 84, presented at the Power Plant Air Pollution Mega Symposium, Baltimore, MD, August, Dombrowski, K.; Arambasick, K.; Chang, R.; Tyree, C. Balance of Plant Effects of Bromide Addition for Mercury Control. Paper 93, presented at the Power Plant Air Pollution Mega Symposium, Baltimore, MD, August, Dickerman, J.; Fitzgerald, H. HCl control by dry sorbent injection (DSI) with hydrated lime. Presented at Air Quality VIII, Arlington, VA, October 23-27, Su, T.; Shi, H.; Wang, J. Impact of Trona-Based SO 2 Control on the Elemental Leaching Behavior of Fly Ash. Energy Fuels 2011, 25, Su, T.; Shi, H.; Wang, J. Impact of Trona-Based SO 2 Control on the Elemental Leaching Behavior of Fly Ash. Energy Fuels 2011, 25, Schantz, M: Sewell, M. The Growth of Dry Sorbent Injection(DSI) and the Impact on Coal Combustion Residue, Presented at AWMA Power Issues Conference, Chicago, IL, July 2013 Page 2

3 cementitious reactions in the resulting mixture. In some fly ashes, this encapsulation mechanism can more than offset the impact of the higher ph resulting from the addition of alkaline sorbents to the system. 6 In short, the impact of DSI reagents to the system on the fly ash should be considered as the leachability of metals will be impacted. Utilities will need to take a coordinated approach to compliance with air emissions regulations (e.g., MATS) and water discharge regulations (ELG). ICAC s member companies recognize the interdependence of these rules. ICAC commends EPA for taking a holistic approach to the fate of metals such as arsenic, mercury, and selenium in coal-fired utility boilers. Specific Comments The proposed effluent limitation guidelines (ELG) includes a provision that encourages plants to eliminate discharges of all process wastewater to surface waters by adopting zero liquid discharge (ZLD) approaches. The provision allows plants that are willing to achieve this high standard to extend the compliance time frame by 5 years to allow time to implement these solutions. This provision is applauded as a means to encourage the elimination of these wastewater streams while recognizing the substantial time needed to plan and implement such an approach. In addition to the several ZLD approaches identified in information with the proposed ELG guidelines, another approach currently in practice in the US is evaporation of the wet FGD wastewater in a spray dryer. Beyond the above proposed provision for encouraging zero wastewater, the proposed rule currently addresses limiting FGD wastewater from larger plants discharging more than 1000 gpm, but the extent of flow minimization is not currently well described. Reducing the quantity of FGD wastewater streams otherwise from plants would clearly provide the intended benefits of the proposed rule and should be included in the rule in a manner to encourage this path for the existing fleet of wet FGD systems. A number of currently available and proven approaches exist that would allow the reduction of the quantity of FGD wastewater including: selecting coals with lower chloride levels thus reducing the need for purging chlorides, installing spray dryers or other systems to partially evaporate the wastewater, installing a dry FGD system or other evaporator system on another boiler unit(s) at the same plant and evaporating/partially evaporating the FGD wastewater from that plant while the unit(s) with the system is operating, and installing dry sorbent injection systems that partially remove chloride upstream of a wet FGD system thus reducing the need to purge chlorides. We urge the EPA to encourage and incentivize the partial reduction of FGD wastewater streams through methods as identified here and other innovative approaches. The incentives should recognize the time frame needed to implement many of these improvements. Incentives that recognize substantial reduction in FGD wastewater on an annual basis should be included. The Page 3

4 Anti-Circumvention Provisions appear at this point to have sound intentions. If a plant chooses a plant-wide ZLD approach, these rules do not apply. Also, it should be made clear that processes which take FGD wastewaters and evaporate all or part of the waste water stream, including those that produce a clean condensate, should not be considered as circumvention. These processes recycle and reuse the FGD wastewater. Once the wastewater stream is evaporated, the dissolved and suspended species from the wastewater stream are dried to a solid and collected with the dry fly ash. It should be noted that when the total dissolved solids (TDS) are dried and added to the fly ash, they may change the properties of the fly ash for disposal or beneficial use purpose. It is known that TDS contains significant levels of halides. The dried halides are very soluble and thus can increase the halide leachability of the fly ash. Overall, these systems are eliminating or significantly reducing the FGD wastewater stream that ends up in surface water and no other wastewater streams result from these processes. Likewise, a plant that equips one or more boiler unit with a system with the capability of evaporating the FGD wastewater from another unit should be clarified as not circumventing the provisions of the guidelines. Again the FGD wastewater steam is being reused, the total FGD wastewater ending up in surface water is either eliminated or significantly reduced, and no other wastewater streams are resulting from this practice. Technologies are being developed and have been implemented in countries such as Hungary and Romania and have been evaluated in the US that transport fly ash using a dense slurry rather than wet (thin slurry) or completely dry ash handling. Fly ash from subbituminous coals is both pozzolonic and contains sufficient lime that it has inherent cementitious qualities. Supplements can be added to other types of fly ash to modify its characteristics. In the presence of water, the material will harden within minutes or hours and gain strength and harden over time. Additives can be combined with the ash to reduce the permeability, and thus the leachability of the stabilized solid. To the extent that plant waste water streams can be utilized as the water source for appropriate amendment of the ash, the ash can provide a mechanism to eliminate leachate from the ash impoundment through formation of a stable and impermeable solid. Any leachate from the impoundment can be reintroduced to the process, making this potentially another approach to achieve zero discharge. We encourage EPA to retain language in the final rule that encourages development of innovative ZLD approaches beyond those described in the proposed rule. Data Concerns FGD waste water chemistry is highly variable and can present considerable treatment challenges. Its composition is dependent on coal type, limestone, makeup water, upstream air pollution Page 4

5 control equipment, and plant operations 6. In light of this, ICAC has concerns regarding the limited number of waste water treatment systems, their scope, and performance data that the EPA used as a basis for the standards. Only (3) chemical precipitation systems, including Miami Fort, Keystone, and Hatfield s Ferry were used. These systems all represent plants that are geographically located in the Ohio River Valley, firing eastern bituminous coals, and likely using waters and limestone sourced from similar origins. Conversely, the EPA cited removal of Pleasant Prairie from their analysis since it was a two stage chemical precipitation. Yet, Pleasant Prairie inclusion would factor in performance and operational data from a plant using water and limestone sourced from the Great Lakes region and firing PRB coal. In addition, Pleasant Prairie is considered one of the more challenging FGD waste waters and has hosted a number industry sponsored pilot technology studies 7,8. The same narrow focus was applied to biological systems. Only (2) were evaluated, both of which are Duke Energy plants located in North Carolina, operating approximately 100 miles apart. Finally, the EPA included only (1) vapor compression system which is not operating domestically, but instead in Brindisi, Italy. It is puzzling why the EPA did not include data from the (2) domestic vapor compression systems in their final analysis. ICAC feels a more expansive review by the EPA to include a broader population of FGD waste water treatment systems and waste water chemistries is not only necessary but responsible in developing standards that are not overreaching of the proposed technologies. Please feel free to call ICAC at (202) with any questions. As always, we stand ready to work with sources, EPA, and states to achieve feasible, measurable, and practical emission limitations. Sincerely, Betsy Natz, Executive Director 6 Treatment%20Options%20for%20FGD%20Wastewater%20by%20Gordon%20Maller,%20URS.pdf 7 CH2MHill, Final Report Prepared for WE Energies. Evaluation of Treatment Technologies for Mercury Removal Pleasant Prairie Power Plant Pleasant Prairie, Wisconsin, December 2008; EPA-HQ-OW [1] 8 EPA/EPRI Meeting, EPRI Water Characterization and Treatment R&D Summary, Washington DC, July 28, 2009; EPA-HQ-OW [1] Page 5