1. Constructed Wetlands for Wastewater Treatment in Small Communities
University of Idaho, College of Art and Architecture Landscape Architecture Program
Gary Austin, Associate Professor

2. Presentation Outline Constructed Wetland Types
Constructed Wetland Performance
Application to Small Communities

3. Constructed Wetland Types
Emergent Plants
Free Floating Plants
Submerged Plants
Floating Leaf Plants
Surface Flow (FWS)
Subsurface Flow
Horizontal Flow (HSF)
Vertical Flow (VSF)
Hybrid
Source: adapted from Vymazal, 2007

4. Free Water Surface Wetland

5. Hybrid Constructed WetlandF G H I
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)

6. Horizontal Subsurface Flow Constructed Wetland

7. Hybrid Constructed WetlandF G H I
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)

8. Vertical Flow Constructed Wetland

9. Vertical Flow Constructed Wetland

10. 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 D E
Both stages planted with Phragmites. Water is gravity fed to all cells- no external energy required

11. Two Stage Vertical Flow Constructed Wetland
Contaminant
Influent
Summer
Winter
% Removal
BOD
340 4 12
98.7
NN4
.29
17.5
NO3
.3-.37
30.9
21.1 TN
53.2
Concentrations in mg/L. Langergraber, 2009
A – Coarse Sand (aerobic) D – Fine Sand (aerobic)
B – Flooded Gravel (anaerobic) E – Drain Rock C – Perforated Under Drain A B C D E

12. Vertical Flow Constructed Wetland

13. Excavation and Forming
Installation
Excavation and Forming

14. Waterproofing Base, geotextile and membrane

15. Perforated drains, drain rock, texture transition and sand filter

16. Cell dividers

17. Drainage detail

18. Filter sand

19. Distribution piping and siphon vault

20. Siphon

21. Distribution manifold and balancing valve

22. Vertical flow wetland in China
Blumberg Engineers –

23. Established Wetland Shenyang, China
Wastewater treatment for 6,000 people
Blumberg Engineers –

24. 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.

25. 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.
Horizontal Flow, planted with Yellow Flag. Area 8m2, cm deep.
HSF, planted with Bur Reed, Acorus. Area 20m2, cm deep.
Aeration stream
To shallow fish pond
Source: adapted from Burka, U.; Lawrence, P. 1990

26. 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 ; Gaboutloeloe, 2009.

27. Koh Phi Phi
Hans Brix, 2006

28. Blumberg Engineers

29. Application for Rural Towns
Cascade, Idaho
Population - 1,000

30. 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

31. Vertical Subsurface Flow Wetland

32. Horizontal Subsurface Flow Wetland

33. Marsh and Open Water Wetlands

34. Re-vegetated for Habitat and Recreation

35. References
Brix, H; Arias, C “The Use of Vertical Flow Constructed Wetlands for On-Site Treatment of Domestic Wastewater: New Danish Guidelines”. Ecological Engineering, 25:
Bulc, T; Slak, A “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:
Cuia, L., Fenga, J., Ouyangb, Y., Dengc, P “Removal of nutrients from septic effluent with re-circulated hybrid tidal flow constructed wetland”. Ecological Engineering, 46:
Hunt, W; Smith, J; Jadlocki, S; Hathaway, J; Eubanks, P "Pollutant And Peak Flow Mitigation By A Bio Retention Cell In Urban Charlotte, N. C." Journal of Environmental Engineering. May 2008.
Kadlec, R., “Wetland Treatment of Leachate from a Closed Landfill” Ecological Engineering, 36 ( ).
Peters, Norman "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”.

36. Questions

37. 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

38. 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, 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.