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Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater
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Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater

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Presentation at 2nd Irish International Conference on Constructed Wetlands for Wastewater Treatment & Environmental Pollution Control. 1-2 Oct. 2010

Presentation at 2nd Irish International Conference on Constructed Wetlands for Wastewater Treatment & Environmental Pollution Control. 1-2 Oct. 2010

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  1. 2nd Irish International Conference on Constructed Wetlands for Wastewater Treatment and Environmental Pollution Control 1st – 2nd October 2010 Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater Mawuli Dzakpasu1, Oliver Hofmann2, Miklas Scholz2, Rory Harrington3, Siobhán Jordan1, Valerie McCarthy1 1 Centre for Freshwater Studies, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland. 2Institute for Infrastructure and Environment, School of Engineering, The University of Edinburgh, Edinburgh EH9 3JL. 3 Water Services and Policy Division, Department of Environment, Heritage and Local Government, Waterford, Ireland.
  2. Presentation outline • Introduction o Background o Aim and objectives • Case study description • Materials and methods • Results • Conclusions • Acknowledgements
  3. Background • Constructed wetlands used to remove wide range of pollutants • High removal efficiency (70% up) recorded for several pollutants e.g. COD, BOD5, TSS • Nitrogen removal efficiencies usually low and variable
  4. Background Integrated Constructed Wetlands (ICW) are: • Free water surface flow wetlands • Predominantly shallow densely emergent vegetated • Multi-celled with sequential through-flow
  5. Background Water treatment ICW Landscape fit concept Biodiversity enhancement ICW conceptual framework
  6. Background • Application of ICW as main unit for large-scale domestic wastewater treatment is novel • Limited information to quantify nitrogen removal processes in full scale industry-sized ICW
  7. Background Nitrogen biogeochemical cycle in wetlands
  8. Research aim and objectives Aim • To evaluate the nitrogen (N) removal performance of a full scale ICW Objectives • To compare annual and seasonal N removal efficiencies of the ICW • To estimate the areal N removal rates and determine areal first-order kinetic coefficients for N removal in the ICW • To assess the influence of water temperature on N removal performance of the ICW
  9. Case study description Location map of ICW site
  10. Case study description • Design capacity = 1750 pe. • Total area = 6.74 ha • Pond water surface = 3.25 ha • ICW commissioned Oct. 2007 • 1 pump station • 2 sludge ponds • 5 vegetated cells • Natural local soil liner • Mixed black and grey water • Flow-through by gravity • Effluent discharged into river
  11. Case study description Process overview of ICW
  12. Materials and methods Wetland water sampling regime • Automated composite samplers at each pond inlet • 24-hour flow-weighted composite water samples taken to determine mean daily chemical quality
  13. Materials and methods Water quality analysis • Water samples analysed for NH3-N and NO3-N using HACH Spectrophotometer DR/2010 49300-22 • NH3-N determined by HACH Method 8038 • NO3-N determined by HACH Method 8171 • Dissolved oxygen, temperature, pH, redox potential, measured with WTW portable multiparameter meter
  14. Materials and methods Wetland hydrology • − + + ( − − ) = • Onsite weather station measures elements of weather • Electromagnetic flow meters and allied data loggers installed at each cell inlet
  15. Data analysis and modelling − = × 100 (1) Co = influent concentrations (mg-N/L) Ce = effluent concentrations (mg-N/L) = × − (2) ℎ: = and = + − − q = hydraulic loading rate (m/yr.); Q = volumetric flow rate in wetland (m3/d); A = wetland area (m2); Qin = volumetric flow rate of influent wastewater (m3/d); P = precipitation rate (m/d); ET = evapotranspiration rate (m/d); I = infiltration rate (m/d)
  16. Data analysis and modelling − ∗ ∗ =− (3) − C* = background concentrations (mg/L); K = areal first-order removal rate constant (m/yr.) () = (20) (−20) (4) K(t) and K(20) = first-order removal rate constants (m/yr.); t = temperature (oC); = empirical temperature coefficient log = log − 20 + log 20 (5)
  17. Results 300 250 250 Rainfall (mm/month) 200 Discharge (m3/day) 200 150 150 100 100 50 50 0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Influent Effluent Rainfall Average rainfall and wastewater discharge at ICW influent and effluent points (April, 2008 – May, 2010)
  18. Materials and methods 39 ± 27.9 m3 day-1 139 ± 65.7 m3 day-1 24.6 ± 12.7% 55.8 ± 11.3% 123 ± 61.8 m3 day-1 44.2 ± 11.3% 106 ± 112.2 m3 day-1 63 ± 371.3 m3 day-1 49.8 ± 23.3% 5.3 ± 2.7% 11 ± 9.4 m3 day-1 ICW water budget
  19. Results 100 Nitrogen (mg-N/L) 10 1 0 0% 1% 15% 29% 68% 96% 100% Influent Sludge Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 pond Ammonia Nitrate Nitrogen removal with cumulative wetland area
  20. Results 100 Nitrogen (mg-N/L) * 10 * * * * * * 1 Summer Autumn Winter Spring Summer Autumn Winter 2008 2009 Ammonia Nitrate Seasonal variations of influent nitrogen to ICW * Indicates significant seasonal variation (P 0.01, n = 18)
  21. Results 10 Nitrogen (mg-N/L) * * 1 * * * * * 0 Summer Autumn Winter Spring Summer Autumn Winter 2008 2009 Ammonia Nitrate Seasonal variations of effluent nitrogen from ICW * Indicates significant seasonal variation (P 0.01, n = 18)
  22. Results 100 12 Removal Effiiency (%) 80 10 HLR (mm/d) 8 60 6 40 4 20 2 0 0 Summer Autumn Winter Spring Summer Autumn Winter 2008 2009 Ammonia Nitrate HLR Seasonal variations of nitrogen removal efficiency and hydraulic loading rate
  23. Results 1800 Removal Rate (mg m-2 d-1) y = 0.988x - 1.551 1200 R² = 0.99 600 a) Ammonia 0 0 600 1200 1800 Loading Rate (mg m-2 d-1) Removal Rate 1000 (mg m-2 d-1) 750 y = 0.952x - 0.111 R² = 0.99 500 250 b) Nitrate 0 0 250 500 750 1000 Loading Rate (mg m-2 d-1) Areal nitrogen loading and removal rates
  24. Results Areal first-order nitrogen removal rate constants in ICW K (m/yr) K20 (m/yr) Parameter  Mean SD n Mean SD n Ammonia 14 16.5 120 15 17.3 101 1.005 Nitrate 11 12.5 101 10 11.3 101 0.984 n = sample number, SD = standard deviation
  25. Results 120 y = -0.081x + 15.56 KA (m/yr) R² = 0.0004 60 (a) Ammonia 0 0 5 10 15 20 25 Water temperature (oC) 80 y = -0.098x + 11.98 KN (m/yr) R² = 0.0009 40 (b) Nitrate 0 0 5 10 15 20 25 Water temperature (oC) Water temperature and reaction rate constants
  26. Results 120 y = 0.05x + 2.23 KA (m/yr) R² = 0.77 60 (a) Ammonia 0 0 500 1000 1500 2000 Loading rate (mg m-2 d-1) 100 y = 0.09x + 4.23 KN (m/yr) R² = 0.66 50 (b) Nitrate 0 0 200 400 600 800 1000 Loading rate (mg m-2 d-1) Nitrogen loading rate and reaction rate constants
  27. Conclusions • High removal rates recorded at all times of the year • Removal efficiency consistently 90 % • Removal rates slightly influenced by seasonality • Strong linear correlations between areal loading and removal rates: NH3-N (R2 = 0.99, P 0.01, n = 120) and NO3-N (R2 = 0.99, P 0.01, n = 101) • Low temperature coefficients are indications that variability in N removal was independent of water temperature
  28. Acknowledgements • Monaghan County Council, Ireland for funding the research. • Dan Doody, Mark Johnston and Eugene Farmer at Monaghan County Council, Ireland, and Susan Cook at Waterford County Council, Ireland, for technical support.
  29. Thank you for your attention! We welcome your questions, suggestions, comments! Contact: mawuli.dzakpasu@dkit.ie

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