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Constructed wetlands for remediation of plumes

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Constructed wetlands for cost-effective and energy-efficient remediation of plumes

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Constructed wetlands for remediation of plumes

  1. 1. Constructed wetlands for cost- effective and energy-efficient remediation of plumes Nicole, June 2018 Frank Pels (HMVT) & Nanne Hoekstra (Deltares) With the cooperation of Jasperien de Weert, Johan van Leeuwen, Bas van der Zaan and Jan Gerritse (Deltares)
  2. 2. Constructed wetlands A constructed wetland (CW) is an artificial swamp in which polluted water is purified Advantages: • optimal use of biological processes • energy-neutral • fully integrated in the landscape • low operational costs • already common practice for waste water treatment, so experiences can be used for innovative application as green soil remediation measure Nicole 2018
  3. 3. Buildingblock (1) –transport • transport of contaminated water Nicole 2018
  4. 4. Buildingblock (2) – design • wetlands are designed specifically for type of pollutant and necessary flow Nicole 2018
  5. 5. Buildingblock (3) – treatment • treatment of contaminants in wetlands Acknowledgement to KH Kempen Nicole 2018
  6. 6. Buildingblock (4) – biodegradation • In the wetland, the pollutants are biodegraded Nicole 2018 Anaerobic
  7. 7. Buildingblock (5) – energy • energy is generated locally Nicole 2018
  8. 8. Amersfoort Railway Site Nicole 2018 Former welding workshop from Dutch rail Birdsview of railyard Amersfoort Contamination ground and groundwater with perchloroethylene (PCE) +100m
  9. 9. Clean up effort(s) Soil excavation in 2007 Nicole2018 Deepwells & pump volumes Q1 8 -16 m –mv, 2 m3/hour Q2 6 -16 m –mv, 2 m3/hour Q3 6 -16 m –mv, 2 m3/hour Q4 6 -16 m –mv, 8 m3/hour Pump & treat (P&T) over period 2009-2011 After 2 years of P&T: design and construct wetland
  10. 10. Final design Nicole 2018 Designed HRT = 8 weeks
  11. 11. Sampling locations Nicole 2018 influent effluent = monitoring well 1.2 – 1.35 m = monitoring well 1.7 - 2.1 m
  12. 12. Construction wetland Nicole 2018 Placing liner and maintenance drains Building wetland with scoria & straw Finished wetland with gravel on top Helofytes planted 10 pcs/m2 2m30m 5m
  13. 13. Field test Nicole 2018 As built June 2013 Start test September 2013 Autumn 2014 Summer 2016
  14. 14. Wind in relation to water flow • Influent ranged from 52 to 1198 L/hr. (1.2 - 28.7 m3/day) • Influent Average = 125 L/hr. (over a period of 19 days) • Flow and residence time are directly coupled to local wind speed over time  important to know local weather circumstances Nicole 2018
  15. 15. Biochemical conditions • Over the flow path: o Redox conditions optimize o Both organisms capable of reductive dechlorination and VC- oxidation develop • Conditions in winter less suitable Nicole 2018
  16. 16. Relative degradation for PCE Nicole 2018 PCE TCE DCE VC Ethene + Ethane
  17. 17. Costs • Design of wind powered wetland: €15.000,- • Construction of wetland €35.000,- • Monitoring & research: €37.500,- • Maintenance cost: €2.500,-/year Nicole 2018
  18. 18. Conclusions Amersfoort Railway site • Full PCE dechlorination in wind powered constructed wetland • Ecological designed concept is self-sustaining • Added straw as slow release compound provided suitable conditions for reductive dechlorination • Tailoring the design to local weather and subsurface conditions is important (micro organisms; DOC, nitrate/sulphate, wind, temperature, contaminant concentrations; etc) • Seasonal variation in wind and temperature affect the system, but it remains sufficient • Optimizing flow paths within the wetland, to increase performance Nicole 2018
  19. 19. House Doorn : interception plume Nicole 2018 Doorn National Monument -Refuge where Emperor Wilhelm II spent his last years after the First World War (1918-1941)
  20. 20. Plume originating from dry-cleaner is intercepted by extraction well for moat Nicole 2018
  21. 21. With purification plume remedation Nicole 2018
  22. 22. Moat monitoring baseline determination PCE: approx 200 - 300 µg/l Oxygen: 3 - 6 mg/l DNA for oxidative VC-degradation present Nicole 2018
  23. 23. Construction works finishd Nicole 2018 Groundwater Extraction well anaerobic zone aerobic zone
  24. 24. Opportunities constructed wetlands in cities Nicole 2018
  25. 25. Partners Nicole 2018 For more information, contact us: frank.pels@hmvt.nl & nanne.hoekstra@deltares.nl

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