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MARDAW Managed Aquifer Recharge Discharge to Artificial Wetlands

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					               MARDAW
   Managed Aquifer Recharge
                         with


Discharge      to   Artificial Wetlands,
                     Capel
                       Bill Scott
             Emeritus Associate Professor
       Environmental Science, Murdoch University
           Outline:
Introduction
What do natural wetlands do?
Capel Wetland Centre CWC
History of Capel WWTP


Evolution of the Project


MARDAW


Design Calculations
What does a natural wetland do?
• Serves as biosphere/storage basin of water for wildlife
   and people
• Is a window to the aquifer, groundwater. In continual
  communication with groundwater and surface waters
    Recharges/refills groundwater during winter & storms
    Discharges/uses groundwater in summer
• Uses/treats biological waste. The most productive
  biological/ecological system
• Acts as a short-circuit or special conducting path for
  groundwater
• Its exposed surface allows evaporation and water loss.

• Here we seek to mimic a few of these features.
Capel Wetland Centre
• Deep History

• Extensive Monitoring

• Several Levels of Models

• Attractive site

• Developing ecosystems
A View of a Bird Hide along Paperbark Lake, looking NW
Planar view of the
Capel Wetland Centre.
Initially plant
effluent discharged
into Swamphen.
Inflow from the plant
ceased in 2000.
     Evolution of the Project
• The deep slimes/metasediments make it difficult
  to maintain nutrients in the lakes.
• The infiltration basins at the WWTP at the Capel
  townsite (about 4 km NE of CWC) have been
  ineffective.
• A cooperative project evolved; the Water
  Corporation has completed a major study for
  using the CWC to discharge treated wastewater.
• MARDAW is a variant of this, with the objective
  of creating sustaining wetland systems.
SAT            --- Soil Aquifer Treatment

• Recharge ponds, infiltration basins permit vertical or
horizontal filtration by soil during recharge to the aquifer
• Requires multiple basins for aeration and recovery from
clogging, scrapping or overturning
• Phosphorus is removed with scraping; nitrogen through
action of denitrifying bacteria


ASR            --- Aquifer Storage and Recovery

• Aquifer is recharged from either a pond or recharge well
• Water is recovered after the water has spent time in the
aquifer, perhaps months, perhaps 10s of years
• Generally nutrients and contaminants are removed by the
filtering and biological actions of the aquifer



MAR             --- Managed Aquifer Recharge

• Aquifer recharged through active infiltration and
percolation and/or recharge wells
• There may be no recovery
• Generally nutrients and contaminants are removed by the
filtering and biological actions of the aquifer
CAW             --- Constructed Artificial Wetlands

• Storage ponds or lagoons are used to treat the water to
acceptable standards.
• Particularly for the later stages of treatment
• Reeds, bullrushes and waterweeds may form part of the
treatment




DAW              --- Discharge to Artificial Wetlands

• Input water is processed in wetlands isolated from the
                                                                 Input
aquifer
• Naturally deviant features, plants, sediments and turbulence
may be used to process the water                                         Output

• Nutrients and chemicals are added or removed to maintain
the wetlands
• Intervention is through removal of plants, sediments and
alterations in the flows (weirs)
MARDAW




                                                                     Groundwtr In
                              --- Managed Aquifer Recharge
with Discharge to Artificial Wetlands

• Input water is processed minimally and/or placed in        Input

carefully monitored wetlands isolated from the
aquifer
                                                                                     Output
• Flow-through lakes mix and dilute the secondary




                                                                     Groundwtr Out
water, which mostly recharges the aquifer
downstream with nutrient displacement
• Plants, sediments and the biology absorb nutrients
• Groundwater flows into lower lakes for more natural
processing, thence to surface water flows
• All lakes have a supported ecology
• Phosphorus is removed by groundwater and
harvesting of plants and sediments
                           Important
                            Concepts
                        Uniform Rainfall & Infiltration




Output to Capel River                                     Output to Ludlow River




    No matter where/when you add water to the
    aquifer, it is stored and useful to nature and people.
The catchment; the Capel and Ludlow Rivers with the CWC, lower left.
Groundwater Inflow                                        Groundwater Outflow



                     Displacement,
                             Dilution and
                                     Confinement effects

                                      of MARDAW
   -The horizontal groundwater inflow mixes with the lake water and
   captures the nutrients in the outflow, even if the inflow and outflow are
   the same

   -The nutrients are stored in the aquifer downstream and are processed in
   the long time frame of the aquifer

   -Some of the lakes are losing water (Swamphen, Island) and some are
   gaining water (Peninsula)
               Components
I. Add wastewater to CWC upper lakes
II. Monitor before and after
III. Maintain the lakes in a Macrophyte
   dominated condition (Chambers)
IV. Initial wastewater flow ~500kL/day --to
   grow to around 3000kL/day
V.   Preprocessing of wastewater
VI. Maintaining redundant treatment ponds and
    dykes
The Hydropolis paper found that:

 The Capel Wetland Centre and the
  Capel Townsite may act in concert and
  use the wastewater as a resource.
 MARDAW; the groundwater, the
  lakes, the biology and sediments
  should deal with nutrient levels for at
  least 10 years.
 The final result could well be
  sustainable ecosystems with minimal
  intervention.
         Carrying on the
              work
MARDAW with groundwater displacement
 allows removal > 85% of the Phosphorus
 and >70% of the Nitrogen over a 10 year
 period.
The level of Phosphorus may approach a
 limit after a few years.
For this paper we add absorption by
 sediments and concentration dependences.
 Tabular results follow
                                                Swamphen Lake
      Water                                                                                  Groundwater Groundwater
                    Inflow        Rainfall        Evaporation Seepage            Overflow
     Balance                                                                                    Inflow     Outflow
       2009            60             23                19                6        50            80              88
       2011            61             23                20                9        47            80              88
       2013            88             23                20                7        76            80              88
       2015           128             23                20                5        118           80              88
     Nitrogen         Input        Seepage        Plant/Animal Denitrifaction Discharge in   Groundwater      Average N
     Balance         tonnes         tonnes           Uptake       tonnes       Overflow        Outflow       in lake mg/L
       2009            1.8          0.037             0.11               0.24      0.18         0.32            3.7
       2011            2.2          0.103             0.21               0.46      0.32         0.60            6.9
       2013            3.8          0.125             0.32               0.71      0.81         0.94            10.7
       2015            5.0          0.114             0.41               0.91      1.61         1.20            13.7
    Phosphorus        Input        Seepage        Plant/Animal Tonnes P in       Discharge   Groundwater Average P in lake
     Balance         tonnes         tonnes           Uptake    Sediments          Tonnes       Outflow        mg/L
       2009            0.6          0.005             0.002              0.215    0.026        0.045           0.513
       2011            0.6          0.016             0.004              0.436    0.050        0.094           1.067
       2013            0.9          0.018             0.006              0.630    0.120        0.139           1.578
       2015            0.9          0.016             0.008              0.764    0.230        0.171           1.946
Values in Ml or tonnes unless noted. Initially 30 mg/l N and 10 mg/l P
                                                     Island Lake
      Water                                                                               Groundwater Groundwater
                    Inflow         Rainfall    Evaporation Seepage         Overflow
     Balance                                                                                 Inflow     Outflow
       2009            50               34          34            8            38             40              44
       2011            47               34          34           10            33             40              44
       2013            76               34          37           16            53             40              44
       2015           118               34         37.6         17.8         92.6             40              44
     Nitrogen         Input        Seepage     Plant/Animal Denitrifaction Discharge in   Groundwater      Average N
     Balance         tonnes         tonnes        Uptake       tonnes       Overflow        Outflow       in lake mg/L
       2009           0.18             0.008     0.019         0.042          0.02           0.03            0.6
       2011           0.32             0.040     0.071         0.158          0.08           0.10            2.4
       2013           0.81             0.150     0.169         0.376          0.30           0.25            5.6
       2015           1.61             0.339     0.343         0.761          1.06           0.50            11.4
    Phosphorus        Input        Seepage     Plant/Animal Tonnes P in    Discharge      Groundwater Average P in lake
     Balance         tonnes         tonnes        Uptake    Sediments       Tonnes          Outflow        mg/L
       2009          0.026             0.004       0.01         0.005        0.001          0.001           0.027
       2011          0.050             0.019       0.01         0.022        0.004          0.005           0.116
       2013          0.120             0.080       0.01         0.056        0.016          0.013           0.301
       2015          0.230             0.192       0.01         0.119        0.060          0.028           0.647
Values in Ml or tonnes unless noted.
                                              Peninsula Lake
      Water                                                                              Groundwater Groundwater
                    Inflow         Rainfall   Evaporation Seepage         Overflow
     Balance                                                                                Inflow     Outflow
       2009            38              21          36            6           147            360             230
       2011            33              22          39            9           137            360             230
       2013            53              22          54           24           127            360             230
       2015           92.6             22         57.8         27.8          159            360             230
     Nitrogen         Input        Seepage    Plant/Animal Denitrifaction Discharge in   Groundwater      Average N
     Balance         tonnes         tonnes       Uptake       tonnes       Overflow        Outflow       in lake mg/L
       2009           0.02         0.0002        0.001        0.0016        0.004          0.006           0.024
       2011           0.08         0.0022        0.008        0.0098        0.020          0.034           0.147
       2013           0.30         0.0227        0.029        0.0378        0.072          0.130           0.567
       2015           1.06         0.0952        0.107        0.1370        0.327          0.473           2.054
    Phosphorus        Input        Seepage     Plant/Animal Tonnes P in   Discharge      Groundwater Average P in lake
     Balance         tonnes         tonnes        Uptake    Sediments      Tonnes          Outflow        mg/L
       2009         0.0010 0.00001              0.00001       0.0002       0.0001          0.0002         0.0007
       2011         0.0038 0.00006              0.00003       0.0011       0.0005          0.0009         0.0038
       2013         0.0159 0.00060              0.00010       0.0046       0.0019          0.0035         0.0150
       2015         0.0599 0.00273              0.00041       0.0180       0.0094          0.0136         0.0590
Values in Ml or tonnes unless noted.
               Assumptions
a) Steady-state, well-mixed lakes
b) Equilibrium sorption following a Langmuir
   isotherm (Chambers and McComb, 1996)
c)   Effects are concentration dependent
d)   Areas and volumes are constant
e)    Average groundwater inflow/outflows
     derived from 1990-2000 algorithm
f) Ignores annual variations in groundwater,
   flows and biology
        These Tables Show:
 N advantage: Biological activity and
 seepage can lower N another 30%

 P advantage: Sorption can lower P by a
 another factor of 2

 P and N concentrations from three
 lakes in series may be insignificant
 even after 6 years.
               Considerations:
 Groundwater, with displacement, can allow the
 system to be sustained, in steady-state.
 Intervention, removal of plants or sediments, or
 export by animals (ducks) should further reduce
 P loading
 Wetting/drying is effective, in denitrification
 but also break-up the metasediments, improving
 water exchange and biological activity
 The anaerobic slime/metasediments at the
 bottom naturally serve the purpose of nitrate
 removal but they are becoming acid from
 exposure (lack of rainfall)
            Conclusions
The Capel Wetland Centre and the Capel
 Townsite may act in concert and use the
 wastewater as a resource.
MARDAW; the groundwater, three lakes,
 the sediments and biology will effectively
 remove or process nutrients for more
 than 6 years with no intervention.
Adding natural turnover and removal, the
 final result could produce sustainable
 ecosystems.
Success with
 MARDAW should be
 seen as as a rival to
 Biosphere-2

				
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