PARAMETER ESTIMATION OF THE POLLUTANT REMOVAL MECHANISMS OF SUBSURFACE HORIZONTAL FLOW CONSTRUCTED WETLANDS TREATING GREYW...
Think Ecologically……. Reduce  Reuse  Recycle
CONTENTS <ul><li>INTRODUCTION </li></ul><ul><li>OBJECTIVES </li></ul><ul><li>MATERIALS AND METHODS </li></ul><ul><li>RESUL...
INTRODUCTION <ul><li>Wetlands are considered as  kidneys of natural ecosystems . </li></ul><ul><li>Natural wetlands are th...
INTRODUCTION cont. <ul><li>Constructed wetlands are  man made features that simulate the functions of natural wetlands . <...
OBJECTIVES <ul><li>Identify the  principal mechanisms of removal  of pollutants. </li></ul><ul><li>Identify   the   key op...
OBJECTIVES cont. <ul><li>Size the surface area in order to optimize the size of the constructed wetland in a most economic...
MATERIALS AND METHODS <ul><li>Experimental Design </li></ul><ul><li>Mathematical formulation for the identified removal me...
DESIGN OF SHF CW SAMPLING POINT 01 SAMPLING POINT 04 SAMPLING POINT 03 SAMPLING POINT 02
MATERIALS AND METHODS cont. <ul><li>Analysis of treatment efficiencies   </li></ul><ul><li>Three samples were tested for e...
<ul><li>Estimation of Reaction Rate Constant </li></ul><ul><li>According to mass conservation; </li></ul><ul><li>In = Out ...
Assuming  first order kinetics  prevail, ( C e  / C i ) = e -K T t   C a  = C e  {(1- e -K T t ) / e -K T t } .………....….. ...
Effective sizing of the constructed wetland Then differentiate the equation (2) w.r.t. t and simplify the equation; d(C e ...
RESULTS Variation of weekly COD  Variation of weekly BOD
Variation of weekly  nitrate nitrogen  Variation of weekly  nitrite nitrogen
Variation of weekly  total kjeldhal nitrogen Variation of weekly  total phosphorous
Variation of weekly  total coliforms  Variation of weekly  total suspended solids
Estimation of reaction rate constants (K T ) using  dessolver 1.7 Graphical representation of the variation of effluent BO...
Estimated reaction rate constants     Parameter Temperature dependant reaction rate constant – K T  (day -1 )±SD BOD 5 0.8...
Estimation of optimum retention time (t opt ) Estimation of optimum retention time (t) for BOD
Estimated retention time for each parameter   Parameter (Reference)   Retention time – t (day)   BOD 5  (50 mg/l) 3.150 CO...
RESULTS cont. <ul><li>Measured flow rate (1 st  stage) :  1428 l/day </li></ul><ul><li>Estimated range of retention time: ...
EFFECT OF LOADING RATE <ul><li>The system was operated at a reduced flow rate (around 650 l/day). </li></ul><ul><li>All th...
Conclusion <ul><li>The temperature dependant reaction rate constants were estimated for each parameter under the  local co...
L E T’S  G O G R E EN for a better world Thank You
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Parameter Estimation of Pollutant Removal for Subsurface Horizontal Flow Constructed Wetlands Treating Greywater

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Treatment efficiencies of a pilot scale constructed wetland treating greywater
from a staff canteen of the University of Moratuwa was studied to estimate the
temperature dependent reaction rate constants of specific pollutant removal
mechanisms.

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Parameter Estimation of Pollutant Removal for Subsurface Horizontal Flow Constructed Wetlands Treating Greywater

  1. 1. PARAMETER ESTIMATION OF THE POLLUTANT REMOVAL MECHANISMS OF SUBSURFACE HORIZONTAL FLOW CONSTRUCTED WETLANDS TREATING GREYWATER Dr. Shiromi Karunarathne MKBS Wijesiri VM Jayasooriya
  2. 2. Think Ecologically……. Reduce Reuse Recycle
  3. 3. CONTENTS <ul><li>INTRODUCTION </li></ul><ul><li>OBJECTIVES </li></ul><ul><li>MATERIALS AND METHODS </li></ul><ul><li>RESULTS AND DISCUSSION </li></ul><ul><li>CONCLUSION </li></ul>
  4. 4. INTRODUCTION <ul><li>Wetlands are considered as kidneys of natural ecosystems . </li></ul><ul><li>Natural wetlands are the nature’s ultimate filters . </li></ul><ul><li>Natural wetlands are being overloaded and malfunctioned rapidly. </li></ul><ul><li>Now we have the need for constructed wetlands . </li></ul>
  5. 5. INTRODUCTION cont. <ul><li>Constructed wetlands are man made features that simulate the functions of natural wetlands . </li></ul><ul><li>Soil, sand, gravel, clay, water, plants and microbes work together to create clean water. </li></ul><ul><li>Understanding the removal mechanisms is a challenge . </li></ul>
  6. 6.
  7. 7. OBJECTIVES <ul><li>Identify the principal mechanisms of removal of pollutants. </li></ul><ul><li>Identify the key operational parameters of SHFCW. </li></ul><ul><li>Estimate the both operational and design parameters under local conditions . </li></ul>
  8. 8. OBJECTIVES cont. <ul><li>Size the surface area in order to optimize the size of the constructed wetland in a most economical and optimal way. </li></ul><ul><li>In order to popularize the constructed wetlands while promoting reuse of treated wastewater. </li></ul>
  9. 9.
  10. 10. MATERIALS AND METHODS <ul><li>Experimental Design </li></ul><ul><li>Mathematical formulation for the identified removal mechanisms. </li></ul><ul><li>Single wetland cell was loaded with the kitchen waste water discharge from one of the university canteens. </li></ul><ul><li>Weekly sampling was done at settling tank 01, settling tank 02, wetland inlet and wetland outlet. </li></ul><ul><li>The inlet and outlet water flows were measured with the aid of the standard methods. </li></ul>
  11. 11. DESIGN OF SHF CW SAMPLING POINT 01 SAMPLING POINT 04 SAMPLING POINT 03 SAMPLING POINT 02
  12. 12. MATERIALS AND METHODS cont. <ul><li>Analysis of treatment efficiencies </li></ul><ul><li>Three samples were tested for each sampling point for the following parameters in the analytical laboratory of the department. </li></ul><ul><ul><li>Biological Oxygen Demand (BOD 5 ) </li></ul></ul><ul><ul><li>Chemical Oxygen Demand (COD) </li></ul></ul><ul><ul><li>Nitrogen content </li></ul></ul><ul><ul><ul><li>Nitrate nitrogen, Nitrite nitrogen and Kjeldhal nitrogen </li></ul></ul></ul><ul><ul><li>Phosphorous content </li></ul></ul><ul><ul><li>Suspended solids </li></ul></ul><ul><ul><li>Physical parameters (Temperature, pH, Turbidity, Conductivity) </li></ul></ul><ul><ul><li>Presence of pathogens (Total Coliforms) </li></ul></ul>
  13. 13. <ul><li>Estimation of Reaction Rate Constant </li></ul><ul><li>According to mass conservation; </li></ul><ul><li>In = Out + Assimilation + losses </li></ul><ul><li>C a = C i – C e ………….……… (1) </li></ul><ul><li>Where; </li></ul><ul><li>C i , C e , C a – influent, effluent and assimilated concentration (mg/l) of a single pollutant respectively </li></ul>MATERIALS AND METHODS cont.
  14. 14. Assuming first order kinetics prevail, ( C e / C i ) = e -K T t C a = C e {(1- e -K T t ) / e -K T t } .………....….. (2) Where; K T – temperature dependent reaction rate constant t – retention time Then differentiate the equation (2) w.r.t. K T and simplify the equation; d(C e )/ d(K T ) = - tC e …...………...….... (3)
  15. 15. Effective sizing of the constructed wetland Then differentiate the equation (2) w.r.t. t and simplify the equation; d(C e )/d(t) = -K T C e ………………….... (4) Maximum retention time is taken that would yield satisfactory levels of treatment, Q = V/t max …………….......................... (5) A = Q.t max /d …………......................... (6) Then, resized surface area can be calculated using above equations.
  16. 16. RESULTS Variation of weekly COD Variation of weekly BOD
  17. 17. Variation of weekly nitrate nitrogen Variation of weekly nitrite nitrogen
  18. 18. Variation of weekly total kjeldhal nitrogen Variation of weekly total phosphorous
  19. 19. Variation of weekly total coliforms Variation of weekly total suspended solids
  20. 20. Estimation of reaction rate constants (K T ) using dessolver 1.7 Graphical representation of the variation of effluent BOD 5 against K T (BOD )
  21. 21. Estimated reaction rate constants     Parameter Temperature dependant reaction rate constant – K T (day -1 )±SD BOD 5 0.80799 ± 0.070 COD 0.61166 ± 0.062 Nitrate Nitrogen 0.80131 ± 0.024 Nitrite Nitrogen 0.85634 ± 0.010 Total Kjeldhal Nitrogen 0.28327 ± 0.050 Total Phosphorous 0.34343 ± 0.078 Total Suspended Solids 0.38157 ± 0.095
  22. 22. Estimation of optimum retention time (t opt ) Estimation of optimum retention time (t) for BOD
  23. 23. Estimated retention time for each parameter   Parameter (Reference)   Retention time – t (day)   BOD 5 (50 mg/l) 3.150 COD (250 mg/l) 2.100 Nitrate Nitrogen (1 mg/l) 3.125 Nitrite Nitrogen (0.005 mg/l) 3.375 Total Kjeldhal Nitrogen (1.2 mg/l) 2.850 Total Phosphorous (3.5 mg/l) 2.525 Total Suspended Solids (30 mg/l) 3.067
  24. 24. RESULTS cont. <ul><li>Measured flow rate (1 st stage) : 1428 l/day </li></ul><ul><li>Estimated range of retention time: 2.1 day – 3.375 day </li></ul><ul><li>Surface area of the resized wetland device: 6.426 m 2 </li></ul><ul><li>Percentage reduction of surface area (1 st stage): 26 </li></ul><ul><li>Percentage reduction of surface area (2 nd stage): 42 </li></ul><ul><li>(at a loading rate of 642 l/day) </li></ul>
  25. 25. EFFECT OF LOADING RATE <ul><li>The system was operated at a reduced flow rate (around 650 l/day). </li></ul><ul><li>All the parameters met satisfactory levels of treatment and treatment efficiencies were found to be increased. </li></ul><ul><li>Estimated reaction rate constants seemed to be changed slightly. </li></ul><ul><li>It is recommended to continue the research at different loading rates in order to verify the results. </li></ul>
  26. 26. Conclusion <ul><li>The temperature dependant reaction rate constants were estimated for each parameter under the local conditions in Sri Lanka . </li></ul><ul><li>It was found that the surface area of the wetland model can be reduced from 8.64 m 2 to 6.426 m 2 which is a 26% . </li></ul><ul><li>The treatment systems can be promoted in highly populated areas at a considerably reduced capital cost . </li></ul>
  27. 27. L E T’S G O G R E EN for a better world Thank You

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