Downstream Drinking Water Impacts of Fossil Fuel Extraction and Utilization Choices

Transcription

1 Downstream Drinking Water Impacts of Fossil Fuel Extraction and Utilization Choices Jeanne M. VanBriesen, Ph.D., P.E. Duquesne Light Company Professor of Civil and Environmental Engineering Director, Water QUEST (Water Quality in Urban Environmental Systems) Carnegie Mellon University Jessica M. Wilson, Ph.D., Assistant Professor Department of Civil and Environmental Engineering, Manhattan College Yuxin Wang, Ph.D., Post-doctoral Researcher Department of Civil and Environmental Engineering, Cornell University Kelly Donmoyer Good, Graduate Research Assistant Department of Civil and Environmental Engineering, Carnegie Mellon University

2 Fossil fuel wastewaters are enriched in bromide Oil and Gas Produced Waters Coal-related Wastewaters Natural Waters Gas produced water mg/l Oil produced water mg/l Wilson, J.M.; Y. Wang; J.M. VanBriesen. Sources of high total dissolved solids to drinking water supply in Southwestern Pennsylvania. ASCE Journal of Environmental Engineering.140, Special Issue: Environmental Impacts of Shale Gas Development, B

3 Source water bromide interacts with disinfectants to form toxic by-products in drinking water source water organic matter (TOC) inorganic matter (Br, I, N) drinking water treatment chemical disinfectant = Br clean drinking water disinfection byproducts (DBPs) DBPs are carcinogenic and teratogenic. 9

4 As bromide concentration in source waters increases, brominated DBPs increase. Br Br Br source water organic matter (TOC) inorganic matter (Br, I, N) drinking water treatment = chemical Yang et al (2014) Toxic impact disinfectant of bromide and iodide on drinking water disinfected with chlorine or chloramine EST 48 : Br Br Br clean drinking water disinfection byproducts (DBPs) DBPs are carcinogenic and teratogenic. Brominated DBPs are more toxic. 10

5 Bromide enters surface waters from natural and anthropogenic sources Background (nonpoint) Saltwater intrusion Runoff Bromide sources Power plant discharges Anthropogenic Oil & gas wastewater Coal mine discharges Road treatment 11

6 The Allegheny Basin has four Centralized Waste Treatment (CWT) facilities, licensed to treat oil and gas brines. Warner, N.R., Christie, C.A., Jackson, R.B., and Vengosh, A. Impacts of Shale Gas Wastewater Disposal on Water Quality in Western Pennsylvania, Environ. Sci. Technol 47 (20)

7 Multiple studies implicated partially-treated oil and gas produced water discharges from CWTs in changing water quality in rivers in Southwestern PA. ASCE Journal of Environmental Engineering 14

8 There are several potential sources of bromide at coal-fired power plants. The coal itself ( natural ) 75 th percentile Median 25 th percentile Bromide at power plants Added for mercury control Cooling water biocide 15

9 Without wet FGD, bromine gas is released in the flue gas With wet FGD, aqueous bromide is released in the wastewater 17

10 The Allegheny River Basin has four large coalfired power plants with wet flue gas desulfurization. Eastern Research Group (2007). EPA-HQ-OW

11 Bromide addition for mercury control could significantly increase bromide loads in the Allegheny River Basin. Power Plant 1 Power Plant 2 Power Plant 3 Power Plant 4 Good, K.D. & VanBriesen, J.M. (2016). Current and potential future bromide loads from coal-fired power plants in the Allegheny River Basin and their effects on downstream concentrations, Environmental Science & Technology, 50(17):

12 The Allegheny River Basin is a Drinking Water source for 1.2 million people. 8 (of 59) drinking water treatment plants are downstream of power plants. This is only 14% of the DWTPs in the basin but approximately 36% of the population served (over 450,000 people). 21

13 Source identification and source sampling allows source apportionment at the Basin Scale. Good, K.D., and VanBriesen, J.M. (2016) Current and potential future bromide loads from coal-fired power plants in the Allegheny River Basin and their effects on downstream concentrations, Environmental Science and Technology. 50(17):

14 Stacked bars show medians Black lines show 25 th -75 th percentile 38 µg/l from wet FGD Bromide concentrations are elevated during low river flow periods such as August. Good, K.D., and VanBriesen, J.M. (2016) Current and potential future bromide loads from coal-fired power plants in the Allegheny River Basin and their effects on downstream concentrations, Environmental Science and Technology. 50(17):

15 Stacked bars show medians Black lines show 25 th -75 th percentile 38 µg/l from wet FGD 116 µg/l from wet FGD and Br addition for mercury control would dramatically increase Br concentrations in August. Good, K.D., and VanBriesen, J.M. (2016) Current and potential future bromide loads from coal-fired power plants in the Allegheny River Basin and their effects on downstream concentrations, Environmental Science and Technology. 50(17):

16 Stacked bars show medians Black lines show 25 th -75 th percentile Eliminating oil and gas wastewater discharges reduces, but does not completely negate, the effect of increased bromide loading from bromide addition at power plants. Good, K.D., and VanBriesen, J.M. (2016) Current and potential future bromide loads from coal-fired power plants in the Allegheny River Basin and their effects on downstream concentrations, Environmental Science and Technology. 50(17):

17 Nationwide, many coal-fired power plants already utilize wet FGD scrubbers for sulfur dioxide control. Adapted from U.S. Energy Information Administration and U.S. Geological Survey data. 32

18 Mercury and Air Toxics Standards (MATS) for Power Plants Steam Electric Power Plant Effluent Limitation Guidelines (ELGs) Requires 90% reduction in mercury emissions. Halogens enhance mercury removal: High-rank coal, better mercury removal Bromide addition can enhance mercury removal Rule finalized on September 30, Depending on site-specific conditions and applicable state water quality standards, it may be appropriate for permitting Timeline for compliance: authorities to establish water quality-based effluent-limitations on bromide, especially where steam electric power plants are located upstream from drinking water intakes. Bromide is not included directly. U.S. Environmental Protection Agency. Effluent Limitations Guidelines and Standards for the Oil and Gas Extraction Point Source Category; Final Rule; U.S. Environmental Protection Agency: Washington, D.C., 2016; Vol.81, pp

19 Conclusions Power plants with wet FGD are contributing significantly to bromide concentrations in the Lower Allegheny River. Spatiotemporal context matters. Dilution may be insufficient to protect downstream drinking water plants as bromide loads increase, especially under low-flow conditions. Bromide addition for mercury control could represent a significant challenge for downstream drinking water plants. 36

20 Acknowledgements 37