The Practical
Application of
Constructed Wetlands
in the Philippines
R.E. James, N. Callora, R. Inion, G. Tolentino
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I. Review
• Background
• Constructed Wetland Types
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Outline
I.
Review
II.
Pilot Testing and Preliminary Results
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–
–
Vegetation Propagation
Pilot Anaerobic Wetland
Pilot Aerobic Wetland with Open Limestone
Channel (OLC)
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I. Review
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Acid Mine Drainage
• Acid Mine Drainage (AMD)
– Sulfide minerals exposed to water and oxygen
4 FeS2 + 15 O2 + 14 H2O  4 Fe(OH)3 + 8 H2SO4
Pyrite + Oxygen + Water  Iron Oxide + Sulfuric Acid
– Fe oxyhydroxides smother vegetation
– Acidity dissolves and mobilizes toxic metals
• As, Cd, Cr, Cu, Fe, Mn, Ni, Zn
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– Contamination of aquatic biota and drinking water
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Constructed Wetlands
Energy sources:
- Photosynthesis
- Topographical gradients
- Microbial metabolism
• Constructed Wetlands
(CW) are a proven
passive wastewater
treatment technology
• Immobilization of metals
as solid precipitates
• Generation of alkalinity
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Wetland Types
• Aerobic Wetlands
– Surface reed ponds
– Metal removal as Fe
precipitation, heavy metal
coprecipitation,
adsortion, physical
settling, and plant-metal
uptake
• Anaerobic Wetlands
– Compost wetland
PROS
CONS
Complicated
water
distribution,
and substrate
design
PROS
CONS
Treats acidic
water
Simple
design and
construction
Requires
alkaline
influent water
Less clogging
of substrate
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CW Modification 1
• Reducing and
Alkalinity
Producing
System (RAPS)
C
B
A
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CW Modification 2
• Limestone Channels
– Open Limestone
Channels (OLC)
• ALD/OLC + aerobic
wetland
• Limestone dissolution
– Pretreatment of pH 3
water
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II. Design Program and
Preliminary Results
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Wetland Components
• Vegetation
• Substrate
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Vegetation
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Substrate
• Nursery batch experiments
• Local substrate
–
–
–
–
Carabao manure
Forest litter
Sawdust from local sawmill
Rice straw
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Results of Batch Experiments
AQUATIC PLANT SPECIES NAME
LOCAL
(TAGALOG)
COMMON
(ENGLISH)
Gabi
Taro
Wate r
Hyacinth
Wate r
Hyacinth
Common
Reed
Bugang
Vetiver
Vetiver
Kankong*
River
Cabbage
METALS ACCUMULATED
TAXONOMY
Colocasia
esculenta
Eichhornia
crassipes
Phragmites
australis
Chrysopogon
nemoralis
Ipomoea
aquatica Forssk
As
Cd
Cr
Cu









Fe
Hg
Mn
Ni
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Zn













• Successful growth of plants in pH 3 test water
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Pb
Hydrology
• Water Balance:
– Mean annual rainfall approximately 3,064 mm
– Mean annual evaporation approximately 1,203 mm
• Highly variable conditions
– Monthly unit base flow ranges from 800 m3/ha/month
to nearly 2,000 m3/ha/month.
– Short-term high intensity storm events show an even
greater range of flows.
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Erosion Controls
• Slope stabilization
– Abaca mats
– Stabilizing vegetation
– Berms
• Water distribution
– Anaerobic conditions?
Constant water supply!
– Trestles
– 3-pond water collection
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Pilot CW Design: RAPS and
OLC + Aerobic Wetland
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Metal Analysis: Plant and Water
18-Sep
Cd
Cr
Cu
Fe
Mn
Ni
Pb
Zn
0.02
0.50
19.2
53.1
22.1
1.2
0.49
2.9
696.4
14
Outflow 0.01
0.00
0.6
0.0
6.8
0.0
0.31
0.6
22.1
3
-46
-100
-97
-100
-69
-100
-37
-79
-97
-79
0.54
0.10
86.1
147.0
10.4
0.5
0.46 11.7
932.6
216
Outflow 0.00
0.04
0.1
0.7
0.0
0.0
0.01
0.1
0.0
184
-100
-62
-100
-100
-97
-99
-100
-15
Inflow
% Change
30-Oct
% Change
Inflow
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-100 -100
Acidity TSS
Pilot RAPS
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OLC + Aerobic Wetland
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Thank You!
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