Selenium Reduction in Constructed Wetland Treatment Systems: Naturally Attenuating Problematic Pollutants

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1 Selenium Reduction in Constructed Wetland Treatment Systems: Naturally Attenuating Problematic Pollutants Katie A. Bland, P.E. Burns & McDonnell Senior Environmental Engineer

2 Overview What are Constructed Wetlands? Why the Power Industry? Westar Energy Pilot Project Pilot Project Results Full Scale Design/Construction Path Forward

3 Constructed Wetland Treatment System Constructed Wetland Treatment System An artificial wetland created or restored..for anthropogenic discharge such as wastewater, stormwater runoff, or sewage treatment. Natural wetlands act as a biofilter, removing sediments and pollutants such as heavy metals from the water, and constructed wetlands can be designed to emulate these features.

4 Three General Systems Free Water Cell Vertical Flow Wetland Constructed Wetland Treatment System Vegetated Submerged Bed Wetland

5 Constructed Wetland Treatment System Free Water Surface Wetland

6 Constructed Wetland Treatment System Vertical Flow Bed Wetland

7 Constructed Wetland Treatment System Vegetated Submerged Bed Wetland

8 CWTS in the Power Industry Stormwater Mine drainage Domestic sewage Landfill leachate Fairly new to the power industry

9 CWTS in the Power Industry A promising technology Polishing FGD Wastewater Landfill leachate/ccr Contact Water Polishing Biological Coal Pile Runoff Stormwater

10 Westar Jeffrey Energy Center

11 Westar Jeffrey Energy Center Polishing FGD Wastewater FGD Scrubber upgrade complete in 2008 Low chlorides Dewatering/solids removal already in place Land available Multiple options considered

12 Westar Jeffrey Energy Center Multiple options considered, with some being complex mechanical systems with high capital costs Wide range in cost between CWTS and ZLD

13 Constructed Wetland Project Jeffrey Energy Center Plant Reuse Pilot Wetland Water / Material Balance Makeup Lake

14 Constructed Wetland Project Jeffrey Energy Center

15 Pilot Wetland Construction Complete

16 Free Water Surface Cell

17 Vegetated Submerged Bed

18 Vertical Flow Bed Wetland Cell

19 Ecological Risks Selenium and Mercury Ecological Exposure

20 Laboratory Column Studies

21 Pilot Constructed Wetland Results CONSTITUENT MASS LOAD REDUCTION AVERAGE INFLUENT (ug/l) AVERAGE EFFLUENT (ug/l) Mercury 83% 1.2 <0.2 Selenium 92% * Boron 42% 3,459 2,120 Fluoride 93% 11,209 1,551 *Selenium: 31% non-detect ( < 5 ug/l )

22 Some Lessons Learned Topsoil Selenium Economically viable It works!

23 Full Scale Design/Construction Considerations for the full scale design Further mitigate ecological risk Flexibility of operation Extensive Modeling Plant Water Balance CORMIX Beneficial Reuse Cooling tower feed Test Pad

24 Full Scale Design/Construction Design Incorporated Ecological Risk Assessment Very Long HRT in CWTS Days Synthetics & Upflow Constructability Challenges

25 Full Scale Design/Construction Isolate Mercury and Selenium

26 Full Scale Design/Construction Tier 1 Soil Gravel/Sand Drainage Layer Geotextile Treatment Soil Single Sided Geocomposite and Gravel Drains Compacted Clay Liner (1x10-7 cm/sec) 60 MIL HDPE

27 Full Scale Design/Construction

28 Full Scale Design/Construction Earthwork completed in December of 2013 Mechanical installation complete in May 2014 Startup of system is ongoing

29 Full Scale Design/Construction

30 Full Scale Design/Construction

31 Wetlands = Opportunity CWTS effectively treats metals including Selenium and other constituents Boron (B) Mercury (Hg) Selenium (Se) Chromium (Cr) Iron (Fe) Molybdenum (Mo) Nitrogen (N) Fluoride (F) Aluminum (Al) Potassium (K) Barium (Ba)

32 Wetlands = Opportunity CWTS provide a green treatment solution that is appealing to the public and local stakeholders Edison Electric Award Winner 2014 Economically appealing Effective for metals reduction

33 Questions? Katie A. Bland, P.E. (816)