Transcript Advances in Constructed Wetlands for Water Treatment

Constructed Wetlands for
Wastewater Treatment in Small
Communities
University of Idaho,
College of Art and Architecture
Landscape Architecture Program
Gary Austin, Associate Professor
[email protected]
Presentation Outline
• Constructed Wetland Types
• Constructed Wetland Performance
• Application to Small Communities
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Constructed Wetland Types
Surface
Flow (FWS)
Emergent
Plants
Horizontal
Flow (HSF)
Subsurface
Flow
Free
Floating
Plants
Hybrid
Vertical
Flow (VSF)
Submerged
Plants
Floating
Leaf Plants
•
Source: adapted from Vymazal, 2007
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Free Water Surface Wetland
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Hybrid Constructed Wetland
I
A
B
C
D
E
F
H
G
Horizontal Subsurface Flow Wetland (left),
A-Inlet from septic tank
B-Horizontal flow through medium to fine gravel
C-Recirculate 50% of flow from VSF to HSF wetland for de-nitrification
D-Collection zone, coarse gravel
E-Water level control
Vertical Flow Subsurface Wetland (right)
F-Intermittent dosing of VSF
G-Water drains vertically through gravel to bottom drain
H-Outflow to free water wetland
I-Dense planting
(Austin, 2009)
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Horizontal Subsurface Flow Constructed
Wetland
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Hybrid Constructed Wetland
I
A
B
C
D
E
F
H
G
Horizontal Subsurface Flow Wetland (left),
A – Inlet from septic tank; B – Horizontal flow through medium to fine
gravel; C – Recirculate 50% of flow from VSF to HSF wetland for denitrification; D – Collection zone, coarse gravel; E – Water level control;
Vertical Flow Subsurface Wetland (right)
F – Intermittent dosing of VSF; G – Water drains vertically through gravel
to bottom drain; H – Outflow to free water wetland; I – Dense planting. (
Austin, 2009)
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• Vertical Flow Constructed Wetland
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• Vertical Flow Constructed Wetland
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Two Stage Vertical Flow Constructed Wetland
A – Coarse sand 2 – 3.2mm (aerobic). Loaded every 3 hours with 16.2mm of water.
Conversion of 80% of the organic material to ammonia and conversion of most
ammonia to nitrate by genus Nitrosomonas and Nitrobacter (some carbon remains).
B – Flooded gravel (3/4’) basin with 3 hour retention time (anaerobic). Residual
carbon is used by different genus of bacteria to convert some of the nitrate to
nitrogen gas (denitrification).
C – Perforated Under drain
D – Fine sand .06-4mm (aerobic) for increased surface area (biofilm) and complete
conversion of carbon to ammonia. Clogging risk is reduced since little carbon or
ammonia remains
E – Drain rock
Langergraber, 2009
A
B
C
Both stages planted with Phragmites. Water is gravity fed to all
cells- no external energy required
D
E
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Two Stage Vertical Flow Constructed Wetland
Concentrations in mg/L.
Langergraber, 2009
Contaminant
Influent
Summer Winter
% Removal
BOD
340
4
12
98.7
NN4
53.459.3
.29
17.5
64-99.5
NO3
.3-.37
30.9
21.1
TN
A – Coarse Sand (aerobic)
B – Flooded Gravel (anaerobic)
C – Perforated Under Drain
A
B
C
53.2
D – Fine Sand (aerobic)
E – Drain Rock
D
E
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Vertical Flow Constructed Wetland
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Installation
Excavation and Forming
http://athene.geo.univie.ac.at/
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Waterproofing
Base, geotextile and membrane
http://athene.geo.univie.ac.at/
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Perforated drains, drain rock, texture transition
and sand filter
http://athene.geo.univie.ac.at/
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Cell dividers
http://athene.geo.univie.ac.at/
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Drainage detail
http://athene.geo.univie.ac.at/
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Filter sand
http://athene.geo.univie.ac.at/
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Distribution piping and siphon vault
http://athene.geo.univie.ac.at/
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Siphon
http://athene.geo.univie.ac.at/
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Distribution manifold and balancing valve
http://athene.geo.univie.ac.at/
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Vertical flow wetland in China
Blumberg Engineers – www.blumberg-engineers.de
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Established Wetland Shenyang, China
Wastewater treatment for 6,000 people
Blumberg Engineers – www.blumberg-engineers.de
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Hybrid Constructed Wetland
Wetland System Plan
1 – Inlet from septic tank, lagoon or
sedimentation basin
2 – Horizontal subsurface flow wetland
3 – Vertical subsurface flow wetland
4 – Deep marsh (18” deep)
5 – Open water (4’ deep)
6 – Shallow marsh (12” deep)
7 – Optional pump
8 – Pipe to return 50% of water from VSF
to HSF wetland for de-nitrification
9 – Distribution, inlet and outlet pipes
All zones are densely planted except for
the open water zone. Austin, 2009.
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Hybrid Wetland at Oaklands Park, UK for
Treatment of Domestic Sewage
VSF, intermittently fed, planted with Phragmites.
Total area 48m2, 40 cm depth of coarse aggregate
covered with 5-10 cm of sand.
VSF, intermittently fed, planted with Phragmites, Iris,
Bulrush. Total area 15m2, 40 cm depth of coarse
aggregate covered with 5-10 cm of sand.
Aeration stream
Horizontal Flow, planted with Yellow Flag. Area 8m2, 40-60 cm deep.
HSF, planted with Bur Reed, Acorus. Area 20m2, 40-60 cm deep.
To shallow fish pond
Source: adapted from Burka, U.; Lawrence, P. 1990
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Oaklands Park Performance
a – EPA discharge requirement less than 30 mg/L
b – No EPA discharge requirement for ammonia. In streams rainbow trout fry tolerate up to about 0.2 mg/L. Hybrid
striped bass can handle 1.2 mg/l.
c - No EPA discharge requirement for nitrate. In streams concentrations above 5 mg/L inhibit growth in fish. Salmon
are much more sensitive.
BOD = biological oxygen demand; TSS = total suspended solids; NH4+ = ammonium; NO3- = nitrate
The pond water met EPA standards for primary contact. E. coli dropped from
500,000 to 0 and fecal Streptococci dropped from 22,000 to 25 cfu/100mL.
The pond contributed significantly to the reduction of harmful bacteria.
Source: Burka, U.; Lawrence, P. 1990 ; Gaboutloeloe, 2009.
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Koh Phi Phi
Hans Brix, 2006
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Blumberg Engineers
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Application for Rural Towns
• Cascade, Idaho
• Population - 1,000
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Existing Sewage Lagoons
Existing sewage lagoons
Existing Area – 22 acres
Conversion plan – downspout
disconnection
Add septic tanks (50,000 gal)
Proposal for population of 2,000
VSF area required – 1 acre to
achieve secondary quality
HSF area required – 2.5 acres to
achieve advanced water quality
Ultraviolet Light
Marsh and open water – 2.5 to 15
acres for advanced water quality,
habitat, recreation
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Vertical Subsurface Flow Wetland
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Horizontal Subsurface Flow Wetland
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Marsh and Open Water Wetlands
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Re-vegetated for Habitat and Recreation
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References
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•
•
•
•
•
•
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Brix, H; Arias, C.2005. “The Use of Vertical Flow Constructed Wetlands for On-Site
Treatment of Domestic Wastewater: New Danish Guidelines”. Ecological Engineering,
25: 491-500.
Bulc, T; Slak, A. 2009. “Ecoremediations – A New Concept in Multifunctional
Ecosystem Technologies for Environmental Protection”. Desalination 245: 2-10.
Chang, J., Wu, S., Dai, Y., Liang, W., Wu, Z. “Treatment performance of integrated
vertical-flow constructed wetland plots for domestic wastewater.” . Ecological
Engineering, 46: 112-114.
Cuia, L., Fenga, J., Ouyangb, Y., Dengc, P. 2012. “Removal of nutrients from septic
effluent with re-circulated hybrid tidal flow constructed wetland”. Ecological
Engineering, 46: 112-114.
Hunt, W; Smith, J; Jadlocki, S; Hathaway, J; Eubanks, P. 2008. "Pollutant And Peak
Flow Mitigation By A Bio Retention Cell In Urban Charlotte, N. C." Journal of
Environmental Engineering. May 2008.
Kadlec, R., 2010. “Wetland Treatment of Leachate from a Closed Landfill” Ecological
Engineering, 36 (946-957).
Peters, Norman. 2009."Effects of Urbanization on Stream Water Quality in the City of
Atlanta Georgia, USA". Hydrological Processes. 23:2860–2878.
van Afferden, M., Rahman, K., Mosig, P., De Biase, C., Thullner, M., Oswald, S., Muller,
R. “Remediation of groundwater contaminated with MTBE and benzene: The potential
of vertical-flow soil filter systems”.
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Questions
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Vertical Subsurface Flow Wetland - Plan
Source: Adapted
from Brix, 2005
A – Inflow from residence B – Septic tank C – Recycling tank with V-notch weirs D –
Effluent E- 1 ½” perforated PVC distribution piping, capped, 3’ spacing F – 4” perforated
PVC drainage piping, 3’ spacing G – Aeration pipes connected to bottom drain H Aluminum polychloride dosing chamber with air-lift pump in septic tank, for phosphorus
removal. Source: Adapted from Brix, 2005
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Vertical Subsurface Flow Wetland - Section
Source: Adapted
from Brix, 2005
A - Wood chips. B – 1 ½” PVC distribution pipes, space 3’ max. C - Uncompacted filter
sand, .125-4 mm with clay and silt <.5%. D- ½ “ drain rock. F - .5 mm waterproof
membrane between two geotextile layers. E – 4” perforated PVC, space 3’ max. At one
end connect to aeration pipes that extend above surface.
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