Floating treatment wetlands were first developed in Japan in the 1990s to absorb nutrients from fish ponds using C. generalis plants, and are now used globally for various applications including water quality improvement, habitat enhancement, and sewage treatment; they provide pollutant removal through physical, biological, and microbial processes aided by planted vegetation; while plant harvesting and environmental factors can impact performance, floating wetlands typically achieve 40-80% removal of nutrients and metals when properly designed and managed.

4. first developed in Japan in the 1990s, with Cana general is being
grown in floating beds to absorb nutrients from fish ponds and
treatment basins
Twenty percent coverage of soilless artificial floating islands,
again using C. general is, was later recommended to improve
water quality in China
The use of Water Hyacinth (Eichhornia crassipes) to remove
nutrients developed in South East Asia, and have been used for
centuries for water treatment within this region
History of FTWs

5. Applications of FTWS
Water quality improvement,
Habitat enhancement
Aesthetic purposes in ornamental
ponds

6. Remediation of sewage effluent in Faisalabad Pakistan
Floating Wetlands for Improving River Water Quality in Indi
Swine Wastewater Treatment (2004)
Treatment of Combined Sewer Overflows in Belgium (2005)
Treatment of Glycol Laden Storm water at Heathrow Airport (1994)
•Main Applications

7. Advantages
of
FTW
Provides design flexibility
Provides a sustainable pollutant-
removal system and wildlife habitat.
Offers resiliency
Improves aesthetics

8. • Four major pollutant reduction mechanisms have been identified in
FTWs:
Physical
Biological uptake
Microbial decomposition.
Plants

9. For maximum nutrient-removal efficiency,
FTWs need to be harvested or removed
seasonally
Non-native and invasive species (plants)
should not be planted
Some contaminants, such as oil and
herbicides could damage the plants and
harm microorganisms
Limitation

10. Value will be lower for homemade FTWs mats constructed either of
recycled materials or PVC pipes.
Costs for vegetation plugs for planting FTWs depends on
vegetation species and source, type of FTW system (harvested
or permanent), and purpose of the FTW.
An estimation of maintenance costs can be made based on the size of the
FTWs and the labour for plant harvesting or replacement, weed
management, etc.
Expected Cost

11. Wastewater
Farms and
horticulture
waste
Factories
and
industrial
waste
Household
waste

12. Phosphorus
Nitrogen
Oxygen
BOD, Suspended solid and Carbon
Components Of Sewage

13. •Impacts of wastewater
Negative impacts on Fish and
wildlife population
oxygen depletion
beach closures Eutrophication
Loss of biodiversity
threats to human health due to
elevated numbers of
pathogenic microorganisms
and toxins created by algal
bloom

14. Summary of the range of wastewater effects on
receiving environments and ecosystem services
Air Water Land
odour, aerosol spray and
vapour:
• spreads of pathogens
• a nuisance to those
living and working in
the surrounding area
• increased nutrients,
organic material
encourages plant
growth and micro-
organism growth
• reduces oxygen
• can cause ecosystem
death
• accumulation of metals,
chemicals
• accumulation of
hormones
• wastewater systems
can deplete soils of
nutrients or cause an
imbalance

15. Freshwater Coastal Forest
 failure of food sources- fishing
reduced ability to absorb wastes
 loss of amenity, unsafe for
recreation
 loss of spiritual health
 failure of food sources – fishing
and shell-fish gathering
 reduced ability to absorb wastes
 loss of amenity, unsafe for
recreation
 loss of spiritual health
 nutrient cycle can be disrupted
– long term impacts - watershed
functions, soils, habitat,
employment

16. Grassland Urban Agriculture
 depletion of soils  public health systems can fail
 high infrastructure costs reduces
ability to provide other social
services
 depletion of soils
 accumulation of heavy metals,
hormone levels affects food
health

17. Process –Phosphorus Removal

18. Settling is a physical process whereby phosphate bound in particles sink to
the bottom
Settling is increased in FTWs by the roots which filter the particles from
the water column to later slough off to settle on the bottom
Also increased by reducing currents and circulation caused by surface
wind disturbance or water movements
P retention within different conventional wetlands ranges from 40-60%
P removal from FTWs is usually higher due to the additional filtering
properties of the roots, reaching 81%
•P removal In FTWs

19. Problems with P removal

20. Nitrogen Removal
Ammonification
• Break down of organic N (example with amino acid) to
ammonia
• RCH(NH2)COOH + H20 → NH3 + CO2
Nitrification :The three stage nitrification process,converting
ammonium to nitrite, then nitrate.
• Nitritation(2 stages)
NH3 + O2 + 2H + 2e- ----------------------------→ NH2OH + H20
NH2OH + H20 ----------------------------→NO2- + 5H + 4e
• Nitrification(1 stage)
2NO2- + O2 ----------------------------→ 2NO3

22. •N Removal by FTW
N removal is predominantly a microbiological process
FTWs have excellent potential for removing N from effluents
Up to 100% N removal is possible, with more tightly controlled conditions
increasing the ability to remove N
C can be added in the anaerobic basin to aid denitrification

23. Oxygen
Submerged photosynthesising plants and algae release O2
during photosynthesis.
Emergent plants bring O2 to the roots, but O2 delivery usually
matches respiration requirements, so there is little net input
into the water column.
Oxygen depletion is likely due to the higher rate of
microbiological activity associated with plant roots.

25. Biological Oxidation Demand
Biological Oxygen
Demand (BOD) is a
measure of oxygen
consumption by
microorganisms
due to
theoxidation of
organic matter
BOD of inflows are
typically high,
unless the
treatment basin is
being used just for
polishing
previously treated
wastes
BOD decreases
rapidly it passes
through a wetland
due to
decomposition and
settling of organic
carbon

26. Processes for Metal Removal
physical filtration and sedimentation
adsorption
Precipitation
complexation
cation exchange
uptake by plants and microbes
microbially-mediated reactions including oxidation and
reduction

28. • (i) Fermentation producing either lactic acid or ethanol.
• (ii) Methanogenesis producing gaseous methane.
• (iii) Sulphate (SO42-) reduction producing carbon dioxide and
hydrogen sulphide.
• (Iv) Denitrification, producing carbon dioxide and gaseous
nitrogen.
Anerobic
Zone

29. Settling is also an important removal method
In FTWs plants have been shown to remove around 5.9 g
BOD/m2/day
Roots also physically entrap particulates onto the biofilm which
then fall in clumps and settle out, providing a significant removal
pathway for suspended solids.
Settling is further encouraged by flow resistance through the
roots and flow reduction caused by wind shielding of the
surface.

30. the net effect of plants in wetlands is to
reduce BOD due to plant respiration,
increased settling, and increased
decomposition processes
where there is carbon limitation in anoxic or
anaerobic basins, the C provided by the
deposition of litter can be important in
increasing denitrification rates
Settling of BOD is also affected by basin
depth, residence time and water movement

31. Theoretically higher temperatures should
increase microbial decomposition rates
In anoxic (reducing)conditions, the presence
of sulphate contributes to the removal of
organic matter (BOD/COD)by acting as a
coagulant and thus increasing settling rates

32. Several studies have confirmed the effect of FTWs in reducing pH.
In a two year study by White and Cousins(2013)pH decreased from 8.6
to 6.2
After only 11 days Vande Moortel et al.(2010)found a significant pH
decrease from 7.5 to 7.0
The researchers who found differences in pH generally agreed that
humic compounds were released by the plants, reducing pH.
alkalinity consumed during microbial nitrification on the plant roots could
also be a driving force behind dropping pH within aerobic basins.
pH

33. For their roots to intercept and filter particulates, aiding sedimentation.
To increase the rates of microbiological processes by providing a high surface
area on which microorganisms respire, nitrify or denitrify.
To increase microbiological processing through the release of humic acids and
through reducing DO exchange and carbon deposition.
• Prime functions of plants in FTWs

34. The start of the growing season, in early spring and prior to
maximum growth rate, is the time of highest P uptake
if removal of P is a priority, harvest timing and frequency
is extremely important, with a recommendation that it is
done not only prior to senescence, but also during the
peak growth period
FTWs typically increase N and P removal rates by around
20-40%, whereas P and N removal by harvesting the
whole plant is at the most 6%.
Storage of nutrients in plant

35. Storage of metals in plants
Storage of metals tends to show
either an even distribution between
roots and shoots (e.g. Cu) or
predominant storage in the roots

36. Variable water depth
Minimum water depth of 0.8 – 1.0 m should be maintained to
prevent the macrophyte roots from attaching to the benthic
substrate
If the roots attach to the basin bottom, there will be a risk that
the floating mat will remain anchored and become submerged
when water levels rise again.
This could potentially lead to the death of the macrophytes and
significant damage to the floating structure
Water Depth

37. dependent on appropriate
design and proper operation
Dependent on characteristics of
the inflow and the objectives of
the treatment
Dependent on concentration on
pollutants
higher inflow concentrations often
results higher removal rates
Treatment Efficiency

38. Consideration for examining performance of FTWs
Dissolved oxygen: aerobic/anoxic/anaerobic. Natural aeration or
artificial aeration
Carbon sources: either naturally, through organic carbon, or
added artificially
pH: with alkaline pH increasing nitrification and acidic pH
increasing denitrification
Root mass: aiding removal of particulates due to physical filtering and
settling processes

39. Continue
Mixing: circulation of water to aid the nutrient supply to microbiological
processes.
Plug flow or continuous flow: affecting residence times and nutrient
gradients
Concentrations of inflow pollutants
Changes in the FTW chemistry with time

40. Seasonal
Variation (i) temperature variations, which affect plant and
especially microbial productivity
(ii) DO variations due to increased oxygen demand when
there is increased microbiological activity
(iii) seasonal growth patterns in plants

41. large and varied
effect on
pollutants
entering a basin
rainfall events can
massively increase
dilution and flow
rates into the
wetland
addition of
rainwater can
alter the water
chemistry
Alter rates of
microbiological
activity, and affect
physical processes

42. Good design of these initial stages is also extremely important in maximising the
treatment efficiency and the cost of running a FTW and to prevent them
becoming unnecessarily clogged by high sludge loadings
Wetlands can easily be overloaded with sludge so pre-treatment and primary
treatment are essential for domestic effluents prior to entering the wetland.
Must be specific to the flow volume, flow variation, the concentrations of
pollutant and the required characteristics of outflow
To achieve treatment objectives careful consideration must betaken in design and
operation of the wetland

43. The treatment potential within a
FTW depends mostly on (i) filtering
capacity of the roots (ii) their surface
area as a microbiological habitat
Choice of plant species affect the
rates of nutrient and metal uptake,
root/shoot biomass division, growth
rates
Also effect the way in which the
basin water chemistry is altered due
to the release of humic acids and
protons by plant roots.
Plants

44. Plant roots assisting in filtering
and settling processes for P
Plant roots acting as a large
surface area for micro-organism
activity in: decomposition,
nitrification, and denitrification.
Mild acidification of water due to
release of humic acids, and a C
input from senescent vegetation;
assisting denitrification
P removal is predominantly a
physical process
Conclusion

45. Metals are also removed predominantly through
binding to particles and sedimentation.
Reduced DO in the basin and disturbance of the
sediments can result in release of P and metals from the
sediments.
Plant uptake only accounts for up to 6% of nutrient (N and
P) removal in FTWs

46. 40%
removal of
metals
80%
removal
of NO3
50%
removal
of NH4+
75%
removal of
TN
60%
removal of
TP
With good management we could expect
a FTW wetland to achieve around

49. LOCAL NAME SCIENTIFIC NAME
1. Alligator weed Alternanther assessiis
2. Bladder wort Utricularia flexuosa
3. Common contail Ceratophyllum demersum
4. Common reed Phragmites communis
5. Curly leaf pond weed Potamogeton crispus
6. Duck weed Lemna paucicostata
7. Eel grass (cock screw) Vallisneria spiralis
Aquatic Vegetation in Punjab

50. LOCAL NAME SCIENTIFIC NAME
8. Gulbakauli (water Hyacinth) Eichhornia crassipes
9. Horned pond weed Zannichellia palustris
10. Hydrilla Hydrilla verticillata
11. Kanwal or Lotus Nelu mbium nelumbo
12. Naiad Najas graminea
13. Pan (cat tail) Typha angustata
14. Water chestnut (Singhara) Trapa bispinosa

51. LOCAL NAME SCIENTIFIC NAME
15.Eurasian water milfoil Myriophyllum spicatum
16. Water lettuce Pistia stratiotes
17. Water lily (Nilofar) Nymphaea lotus

52. Aquatic Plants of KPK
SCIENTIFIC NAME LOCAL NAME
1. Alternanther asessilis Sessile joyweed
2. Bacopa moneiri Waterhyssop
3. Bolboschoenus affinis 4. B. glaucus
5. Brachiaria ramosa Browntop millet
6. Centella asiatica Pennywort
7. Coronopus didymus Swine cress
8. Echinochloacrus-galli Barnyard grass

53. SCIENTIFIC NAME LOCAL NAME
9.Paspalum papaliodes Water grass
10.Oxalis carniculata Wood-sorrel
11.Phalaris minor Bird’s seed grass
12.Phragmites karka Common reed
13. Phyla nodiflora Frogfruit,capeweed
14.Oxalis carniculata Wood-sorrel
15. Rumex detatus Toothed dock

54. SCIENTIFIC NAME LOCAL NAME
16.Typha elephantina Elephant grass
17.Typha domingensis Southern cat-tail
18.Suaeda fruticosa Sea Blite
19.Rumex detatus Toothed dock
20. Portulaca oleracea Purslane
21.Polygonum barbata Joint Weed

55. Area for constructed wetland =2275 sq. feet
Cost FTW mats range from RS.104 to Rs.2496 per square foot depends on type of material used.
Minimum Cost for construction of mats for an area of 760 sq. feet is Rs. 79,040 .
Cost for 1 rose plant is Rs. 50 and for 200 plants is Rs. 10,000.
Other cost depends on the number of labours.
Cost estimation for FTW