際際滷

際際滷Share a Scribd company logo

Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater

Mawuli Dzakpasu
Mawuli Dzakpasu

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

1 of 29
Downloaded 147 times
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, Siobh叩n 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.
Presentation outline Introduction o Background o Aim and objectives Case study description Materials and methods Results Conclusions Acknowledgements
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
Background Integrated Constructed Wetlands (ICW) are: Free water surface flow wetlands Predominantly shallow densely emergent vegetated Multi-celled with sequential through-flow
Background Water treatment ICW Landscape fit concept Biodiversity enhancement ICW conceptual framework
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
Background Nitrogen biogeochemical cycle in wetlands
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
Case study description Location map of ICW site
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
Case study description Process overview of ICW
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
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
Materials and methods Wetland hydrology 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + (鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申)鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 Onsite weather station measures elements of weather Electromagnetic flow meters and allied data loggers installed at each cell inlet
Data analysis and modelling 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = 100 (1) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 Co = influent concentrations (mg-N/L) Ce = effluent concentrations (mg-N/L) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 (2) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申: 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申 and 鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 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)
Data analysis and modelling 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = (3) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 C* = background concentrations (mg/L); K = areal first-order removal rate constant (m/yr.) 鐃緒申鐃緒申鐃緒申(鐃緒申鐃緒申鐃緒申) = 鐃緒申鐃緒申鐃緒申(20) 鐃緒申鐃緒申鐃緒申 (鐃緒申鐃緒申鐃緒申20) (4) K(t) and K(20) = first-order removal rate constants (m/yr.); t = temperature (oC); 鐃緒申鐃緒申鐃緒申 = empirical temperature coefficient log 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 = log 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 20 + log 鐃緒申鐃緒申鐃緒申 20 (5)
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)
Materials and methods 39 賊 27.9 m3 day-1 139 賊 65.7 m3 day-1 24.6 賊 12.7% 55.8 賊 11.3% 123 賊 61.8 m3 day-1 44.2 賊 11.3% 106 賊 112.2 m3 day-1 63 賊 371.3 m3 day-1 49.8 賊 23.3% 5.3 賊 2.7% 11 賊 9.4 m3 day-1 ICW water budget
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
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)
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)
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
Results 1800 Removal Rate (mg m-2 d-1) y = 0.988x - 1.551 1200 R族 = 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 R族 = 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
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
Results 120 y = -0.081x + 15.56 KA (m/yr) R族 = 0.0004 60 (a) Ammonia 0 0 5 10 15 20 25 Water temperature (oC) 80 y = -0.098x + 11.98 KN (m/yr) R族 = 0.0009 40 (b) Nitrate 0 0 5 10 15 20 25 Water temperature (oC) Water temperature and reaction rate constants
Results 120 y = 0.05x + 2.23 KA (m/yr) R族 = 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) R族 = 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
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
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.
Thank you for your attention! We welcome your questions, suggestions, comments! Contact: mawuli.dzakpasu@dkit.ie

More Related Content

Nitrogen Removal in Integrated Constructed Wetland Treating Domestic Wastewater

  • 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, Siobh叩n 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
  • 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 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + (鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申)鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 Onsite weather station measures elements of weather Electromagnetic flow meters and allied data loggers installed at each cell inlet
  • 15. Data analysis and modelling 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = 100 (1) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 Co = influent concentrations (mg-N/L) Ce = effluent concentrations (mg-N/L) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 (2) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申: 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申 and 鐃緒申鐃緒申鐃緒申 = 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 + 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 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 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 = (3) 鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 C* = background concentrations (mg/L); K = areal first-order removal rate constant (m/yr.) 鐃緒申鐃緒申鐃緒申(鐃緒申鐃緒申鐃緒申) = 鐃緒申鐃緒申鐃緒申(20) 鐃緒申鐃緒申鐃緒申 (鐃緒申鐃緒申鐃緒申20) (4) K(t) and K(20) = first-order removal rate constants (m/yr.); t = temperature (oC); 鐃緒申鐃緒申鐃緒申 = empirical temperature coefficient log 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 = log 鐃緒申鐃緒申鐃緒申 鐃緒申鐃緒申鐃緒申 20 + log 鐃緒申鐃緒申鐃緒申 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 賊 27.9 m3 day-1 139 賊 65.7 m3 day-1 24.6 賊 12.7% 55.8 賊 11.3% 123 賊 61.8 m3 day-1 44.2 賊 11.3% 106 賊 112.2 m3 day-1 63 賊 371.3 m3 day-1 49.8 賊 23.3% 5.3 賊 2.7% 11 賊 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 R族 = 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 R族 = 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) R族 = 0.0004 60 (a) Ammonia 0 0 5 10 15 20 25 Water temperature (oC) 80 y = -0.098x + 11.98 KN (m/yr) R族 = 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) R族 = 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) R族 = 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