A general view for the designs of constructed wetlands, uses in water remediation and an example of constructed wetland in Lebanon

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Master 2: Phytoecology, Resources, Security and Applications
PHTE 501
Presented by: Lina Al Rifai
Instructor: Dr. Nabil Amacha
Date of presentation: 25 January 2018
Water Bioremediation through
Constructed Wetlands

2. Outline
Wetlands
I. Horizontal Flow Constructed Wetlands
II. Vertical Flow Constructed Wetlands
III. Free Water Surface Constructed Wetlands
IV. Hybrid Constructed Wetland
V. Kherbit Kanafar Wetland- Lebanon
Advantages of Wetlands

3. Wetlands
• Before 1953, wastewater treatment among experts was limited to physical,
chemical and biological (bacterial) methods
• In 1953, Dr. Käthe Seidel for the first time presented methods for improvement of
inland waterways which suffered from
1. Over-fertilizaton
2. Pollution from sewage
3. Siltation
by means of appropriate plant species . Then, global wetland constructions has
been started in the last 3 decades of 20th century
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(J. Vymazal. 2008)

4. I. Horizontal Subsurface Flow Constructed
Wetland (HF-CW)
As wastewater flows horizontally through the basin, the filter material filters out
particles and microorganisms degrade the organics
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Akvopedia.org

5. I. Horizontal Subsurface Flow Constructed
Wetland (HF-CW)
Advantages Disadvantages/limitations
1. High reduction of BOD, suspended
solids and pathogens
2. Does not have the mosquito problems
3. No electrical energy is required
4. Low operating costs
1. Requires a large land area
2. Little nutrient removal
3. Long maturity period to work at full
capacity
4. Requires expert design and
construction
5
Akvopedia.org
Table 1: This table shows the main advantages and disadvantages of the (HF-CW)

6. Municipal/
domestic
Industrial
Agricultural
Runoff waters
Landfill lechate
(J. Vymazal. 2008)
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Table 2: Examples of the use of free
water surface constructed
wetlands for various types
of wastewater

7. II. Vertical Flow Constructed Wetland
(VF-CW)
• Wastewater is poured intermittently onto the surface from above using a
mechanical dosing system.
• The water flows vertically down through the filter matrix
• Collected in a drainage pipe.
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Akvopedia.org

8. II. Vertical Flow Constructed Wetland
(VF-CW)
Advantages Disadvantages/limitations
1. High reduction of BOD, suspended
solids and pathogens
2. Ability to nitrify due to good oxygen
transfer
3. Does not have the mosquito
problems
4. Requires less space than other
wetlands
5. Low operating costs
1. Requires expert design and
construction, particularly, the dosing
system
2. A constant source of electrical
energy
3. Requires more frequent
maintenance than other wetlands
4. Long maturity period to work at
full capacity
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Akvopedia.org
Table 3: This table shows the main advantages and disadvantages of the (VF-CW)

9. II. Vertical Flow Constructed Wetland
(VF-CW)
(J. Vymazal. 2008)
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Table 4: Examples of the use of vertical flow constructed wetlands for various types of wastewater

10. III. Free-Water Surface Constructed
Wetland (FWS-CW)
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Aims to replicate the naturally occurring processes of a natural wetland, marsh
or swamp.
Akvopedia.org

11. III. Free-water Surface Constructed
Wetland (FWS-CW)
As water slowly flows through the wetland, there are:
.
sedimentation
pathogens are
destroyed
plants utilize
the nutrients
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12. III. Free-water Surface Constructed
Wetland (FWS-CW)
Advantages Disadvantages/limitations
1. High reduction of BOD and solids;
moderate pathogen removal
2. Can be built and repaired with
locally available material
3. No electrical energy is required
4. Low operating costs
1. May facilitate mosquito breeding
2. Requires a large land area
3. Long maturity period to work at full
capacity
4. Requires expert design and
construction
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Akvopedia.org
Table 5: This table shows the main advantages and disadvantages of the (FWS-CW)

13. IV. Hybrid Constructed Wetlands
• Combination of various types of constructed wetlands
• Achieving higher removal efficiency specially for nitrogen
1. HF: denitrification (anaerobic decomposition)
2. VF: Nitrification (aerobic decomposition)
3. FWS: nitrification and denitrification
NH3 NO2- NO3-
NO3- NO2- NO N2O N2
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14. IV. Hybrid Constructed Wetlands
Long maturity period
and expert design
Yes Yes Yes
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Table 6: This table shows the main characteristics of the different constructed wetlands (prepared by
the author)

15. IV. Hybrid Constructed Wetlands
(J. Vymazal. 2008)
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Table 7: Examples of the use of hybrid flow constructed wetlands for various types of wastewater

16. V. Kherbit Kanafar Wetland- Lebanon
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17. V. Kherbit Kanafar Wetland- Lebanon
• Location: adjacent to the Litani River
at the Kherbit Kanafar irrigated lands
• (LRBMS–USAID funded project) with
(LRA) designed and constructed a wetland
system between 2012 and 2013.
(Amacha, N., 2017) 17

18. V. Kherbit Kanafar Wetland- Lebanon
• Inlet from Litani River  wetland  outlet into Litani River
• Plants used: Phragmites australis and Sparganium erectum to mimic the
historical aquatic features of the Litani River (avoiding impacts of invasive species)
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19. V. Kherbit Kanafar Wetland- Lebanon
Design
1. 2.5 ha
2. Horizontal flow constructed wetland
3. oval-shaped basin
4. alternating deep ponds (2-3 m of depth)
and shallow zones (30-50 cm of depth)
(Amacha, N., 2017)
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20. V. Kherbit Kanafar Wetland- Lebanon
Strikingly higher removal efficiencies of nutrients, DO and BOD than the expected
values
Parameter
Experimental Level
(%) Expected Level (%)
NH3 93.30 59.00
NO3
-
62.47 51.00
PO4
3-
82.82 35.00
BOD 66.08 35.50
Experimental and expected levels of Litani river’s
wetland performance.(Amacha,N., 2017) 20
Table 8 : This table shows Experimental and expected levels of Litani
river’s wetland performance

21. Advantages of Wetlands
Wetlands are not only water quality improvers but also
they have ecological benefits to the ecosystem they
are constructed in, some of the benefits:
1. Recharging ground water!
2. Providing excellent habitat for many fish and wildlife species
3. Reducing soil erosion
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Thank you !

23. References
1. Amacha.N, et al. 2017. Assessment of the Efficiency of a Pilot Constructed
Wetland on the Remediation of Water Quality; Case Study of Litani River,
Lebanon. Environment Pollution and Climate Change
2. J. Vymazal. 2008. Constructed Wetland for wastewater treatment: A Review.
Institue of Systems Biology and Ecology, Czech Academy of Sciences,
Dukelská 145, 379 01 Třeboň, Czech Republic
3. Akvopedia.org [the information accessed on 6/1/2018]
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