This document discusses using phytoremediation as a tertiary treatment for sewage. Phytoremediation uses plants to remove pollutants from wastewater and soil. It describes how plants and their associated microbes break down and absorb contaminants like heavy metals, nutrients, and organic compounds. The document evaluates phytoremediation systems like constructed wetlands that use aquatic plants for wastewater treatment. Studies show these systems effectively reduce COD, BOD, nutrients and other pollutants in sewage at a lower cost than conventional tertiary methods. The conclusion is that phytoremediation provides a sustainable, inexpensive alternative to traditional wastewater treatment, especially suitable for developing countries.

1. Phytoremediation, an Option for
Tertiary Treatment of Sewage
Dr. Arvind Kumar Mungray
Chemical Engineering Department,
SVNIT, Surat

2. 2
INTRODUCTION
 Water pollution is one of the most serious problems of today’s civilization.
 Major impact on the Rivers, Lakes, Oceans by
 Deforestation of Riparian zones,
 Inundating fields with Fertilizer,
 Faulty septic systems or Poorly designed waste water overflow systems.
 If drastic efforts in water protection are not made by year 2025, 2.3
billion people will live in areas with chronic water shortage (WHO, 2005).
[1]
 Wastewater treatment is classified in two basic groups:
 Conventional methods and
 Alternative methods.

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Conventional Methods
The method involves:-
 Primary,
 Secondary, &
 Tertiary, or Advanced
Stages.
 Primary treatment removes of
about 30-50% of the Suspended
Solids in raw wastewater by
Sedimentation.
 The organic matter is extracted
by Biological Secondary treatment
processes using activated-sludge
processes, trickling filters, or
rotating biological contactors to
meet effluent standards.
Figure 1:- Sewage Treatment

4. Figure 3:- The Advanced Tertiary Treatment.
4
Tertiary Treatment
The final stage of the treatment involves,
1. Nitrogen Reduction,
2. Phosphorus Reduction &
3. Disinfection.
Figure 2:- Chlorination tank
• Disinfection is done for the removal of the pathogens and is usually
done by either chlorination, ultra- violatilization, or ozonation.

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Where the Method Fail…..
• The treatment fails in satisfying all demands of ecologically aware
societies.
• Do not enable Reclamation and Reuse of water and nutrients,
• Generated effluent not up to the standards,
• Harmful to environment and people.
• Unable to handle storm water.
Source: abc news 09/08/2007
Beachwood beach in U.S.
• In Boston, often beaches are closed as bacteria levels reach hazardous
levels due to untreated raw sewage and urban water runoff enters the
river and bay. Another city headed toward a parallel scenario was
Chicago and its relationship with adjacent Lake Michigan. [2]
• Huge algal blooms in the Mississippii River and it’s tributaries, cultural
Eutrophication leads to oxygen-poor situations, making it difficult for
aquatic life to continue.[2]

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Continued……..
• Higher quality of effluent employs additional technologies results in
increased costs of construction, operation, and maintenance, resulting in
ignorance of this step.
• Water is often dumped directly into neighboring lakes or rivers, which
bear the burden of dealing with these excess pollutants. Pollutants such
as organic matter, suspended particulates, micropollutants,
nutrients (phosphorus and nitrogen) or heavy metals.
• EFFECTS:-[2]
• High concentrations of Nitrates & Phosphates leads to Infant
methemoglobinemia [blue baby syndrome].
• Chlorine combined with nitrate or phosphate forms a carcinogenic
compound.
• High Phosphate levels in streams attributed to algal blooms.

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Alternatives…
Phytoremediation
Bio-remediation

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PHYTOREMEDIATION
• Phytoremediation is an emerging ‘green bioengineering technology’
that uses plants to remediate environmental problems.
• Green plants (both aquatic and terrestrial) have the wonderful properties
of environmental restoration, such as decontamination of polluted soil
and water. [3]
• They are aesthetically pleasing, passive, solar-energy driven and
pollution abating nature’s (green) technology meeting the same
objectives conventional technology and thus becoming a cost-effective,
non-intrusive, and a safe alternative.
• They thrive in very harsh environmental conditions of soil and water;
absorb, tolerate, transfer, assimilate, degrade and stabilise highly toxic
materials (heavy metals and organics such as solvents, crude oil,
pesticides, explosives and polyaromatic hydrocarbons) from the polluted
soil and water.[3]

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Phyto-volatilization
Figure 5: Phyto-volitilization of organic compounds [4]

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Phytodegradation
Figure 6: Phytodegradation of organic & inorganic compounds [4]

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Phytoaccmulation
Figure 7: Phytoaccumulation of organic compounds [4]

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Rhizodegradation
Figure 8: Rhizodegradation of organic compounds [4]

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Phytostabilization
Figure 9: Phytostabilization of organic & inorganic compounds [4]

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How they achieve it….
• The symbiotic relationships
between their basic components,
aquatic plants, microorganisms,
algae, substrates and water they
have the ability to remove
organic and inorganic matter,
nutrients, pathogens, heavy
metals and other pollutants from
wastewater in a completely
natural way.[3]
• The plants species like, cattails,
bulrushes, reeds and aquatic
plants like water hyacinths,
pennywort, and duckweed
were found useful.
Figure 10: Pathway of Contaminants through the Plant [6]

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Inside the Plant Cell-wall….
Figure 11: Pathway of Contaminants inside the Plant Cell wall [6]

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Type and Contaminants…..
Mechanism Media Typical contaminants Plants Types
Phytostablization Soils, sediments, Sludges. As, Cd, Cr, Cu, Pb, Zn Herbaceous species, grasses,
trees, wetland species.
Rhizodegradation Soils, sediments, sludges,
groundwater.
Organic compounds (TPH,
PAHs, BTEX) pesticides,
chlorinated solvents,(PCBs)
Herbaceous species, grasses,
trees, wetland species.
Phytoaccumulation Soils, sediments,
sludges
Metals: Ag, Au, Cd, Co, Cr,
Cu, Hg, Mn, Mo, Ni. Pb. Zn.
Herbaceous species, grasses,
trees, wetland species.
Phytodegradation Soils, sediments, sludges,
groundwater, surface water
Organic compounds,
chlorinated solvents,
phenols,pesticides,munition
Algae, herbaceous species,
grasses, trees, wetland species
Phytovolatization Soils,sediments,
sludges,groundwater
Chlorinated
solvents,MTBE,some
inorganics
(Se,Hg&As)
Herbaceous
species,grasses,trees,wetland
species
Evapotranspiration Groundwater,surface,storm
water
Water soluble organic &
inorganics
Herbaceous
species,grasses,trees,wetland
species
Table 1:- Summary of Phytotechnology Applications [4]

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Efficiency results of a UASB reactor
coupled with a Duckweed pond
Table 2:- Efficiency of treatment system as % removal [9]
Parameter Treatment unit
UASB Duckweed ponds efficiency Overall efficiency
Summer (%) Winter (%) Summer (%) Winter (%) Summer (%) Winter (%)
COD %
removal
79 ± 5 70 ± 1.8 64 ± 17 72 ± 1.3 93 ± 4 92 ± 0.4
BOD %
removal
82 ± 5 73 ± 2 73 ± 12 75 ± 3 95 ± 2 93 ± 1
Ammonia N
% removal
4 ± 14 19 ± 3 98 ± 4 44 ± 7 98 ± 3 39 ± 10
TKN %
removal
26 ± 9 15 ± 5 80 ± 6 45 ± 5 85 ± 4 53 ± 7
Total P%
removal
20 ± 9 28 ± 5 73 ± 8 40 ± 8 78 ± 7 57 ± 7
TSS %
removal
83 ± 7 73 ± 3 43 ± 21 63 ± 6 91 ± 5 91 ± 2
Faecal
coliform %
removal
63 73 99.93 99.7 99.998 99.94

18. Table 3:-Characteristics of pond system influent (UASB reactor effluent) and effluent, and removal efficiencies [10]
18
Duckweed pond Efficiency…
Parameter Concentration (mg/l) Removal efficiency(%)
Influent (%) Effluent (%)
BOD total 23 ± 13 8 ± 5 60 ± 32
BOD filtered 13 ± 6 4 ± 2 65 ± 25
BOD suspended 10 ± 8 4 ± 4 67 ± 26
COD total 126 ± 81 49 ± 20 54 ± 24
COD filtered 54 ± 37 29 ± 20 41 ± 37
COD suspended 72 ± 62 20 ± 20 65 ± 33
TSS 35 ± 30 11 ± 4 57 ± 29
NH4-N 48 ± 18 26 ± 12 46 ± 26
NO3-N Negligible 2 ± 1 -
N-Organic 6 ± 9 Negligible 100
PO4-P 16 ± 3 11 ± 4 33 ± 29
pH 7.4 ± 7.9 7.3 ± 8.3 -

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Efficiency results of a UASB reactor
coupled with a Water hyacinth (WH) pond
Table 4:- Efficiency of the USAB and Water Hyacinth pond [10]
Type ph Alkali
(mg/l of
CaCO3 )
COD
(mg/l)
TSS
(mg/l)
ECOD
%
ETSS
%
Influent 8.15 618 465 154
Effluent
UASB
8.05 635 162 41 65 73
Effluent
(WH)
8.00 620 90 12 81 92

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Comparison of Cost & Time….
Type Of Treatment Cost/m3 ($) Time Req
(months)
Additional factors/expense Safety
Issues
Land filling 100-400 6-9 Long term monitoring Leaching
Soil extraction, leaching 250-500 8-12 5,000m3 minimum Chemical
recycle
Residue
disposal
Phytoremediation 15-40 18-60 Time /land commitment Residue
disposal
Table 5:- Cost Advantage of Phytoremediation [4]

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Advantages & Disadvantages…
 Advantages
1. Natural
2. Green, growing
3. Aesthetically pleasing
4. Cost-effective for large land
areas where other
technologies are not
feasible
5. Sensible, appropriate,
sustainable technology
 Disadvantages
1. Long clean-up times
2. Uncertain performance
3. Not for every site (deep
wastes, anaerobic soils,
etc)
4. Regulatory hurdles
[8]

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To Apply Phytoremediation…..
• Wetlands offer an unlimited potential for the phytoremediation of toxins
and pollutants.
They offset the cost of chemical
treatments and are an alternative
to regions too remote, too small,
or too economically
disadvantaged to support
standard waste water treatment
plants.
Figure 12: A Constructed Wetland
• Wetlands are shallow (typically less than 0.6 m (2 ft)) bodies of slow-moving
water in which dense stands of water tolerant plants such as
cattails, bulrushes, or reeds are grown. In manmade systems, these
bodies are artificially created and are typically long, narrow trenches or
channels.[5]

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Types of Wetlands Treatment
system are:
 Natural Wetlands.
 Constructed Wetlands.
1. Free Water Surface
System,
2. Subsurface Flow
Systems.
 Aquatic Plant Systems.
1. Floating Plant
Systems,
2. Submerged Plant
Systems.
[5]
Figure 13: Treatment Wetlands

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Treatment Wetlands
Figure 14: A Treatment Wetland depicting the various methods of Phytoremediation [4]

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Alternative Methods
Figure 15: A proposed Step for Wastewater treatment using Phytoremediation [7]

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CONCLUSIONS
 The 'green technologies' are more appropriate for water clean up as:-
• Decompose organic pollutants to non-toxic low molecular
substances,
• Do not introduce additional chemical substances into the
environment,
• Are relatively easy to manage and easily adopted to the local
needs,
• Do not require large investment to be practically introduced,
• Are able to remove several pollutants in combination,
• Can be applied at a small as well as at a large scale.
 Is a sustainable & inexpensive process is fast emerging as a viable
alternative to conventional remediation methods, and will be most
suitable for a developing country like India.
 In India commercial application of Phytoremediation of soil heavy metal
or organic compounds is in its earliest phase.

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References….
1. "WHO, Water Resource Quality." http://www.who.int/ (11/17/05).
2. Loeffler R. 2001. A Study of Three Aquatic Plant Species and Their Effectiveness at
Removing Nitrates and Phosphates from a Nutrient Enriched Aqueous Solution,
Sewanee,University of the South, Ecology 210.
3. Sinha R.K., Heart S. and Tandon P.K. 2007. Phytoremediation: Role of Plants in
Contaminated Site Management, Environmental Bioremediation Technologies, Chapter 14,
pp 315-318.
4. ITRC, April 2001, “Phytotechnology Technical and Regulatory Guidance Document”,
Interstate Technology and Regulatory Cooperation Work Group, Phytotechnologies Work
Team, Columbia, U.S.
5. Terry N., Banuelos G.S. 2000. Phytoremediation of Contaminated Soil and Water, Chapter 2,
pp 13-18.
6. Schnoor J.L, 1997 “Phytoremediation”, Ground-Water Remediation Technologies Analysis
Center (GWRTAC), Technology Evaluation Report, pp 11.
7. Peter Schröder, Juan Navarro-Aviñó, Hassan Azaizeh, Avi Golan Goldhirsh, Simona
DiGregorio, Tamas Komives, Günter Langergraber, Anton Lenz, Elena Maestri, Abdul R.
Memon, Alfonso Ranalli, Luca Sebastiani, Stanislav Smrcek, Tomas Vanek, Stephane
Vuilleumier & Frieder Wissing. December 2006, “Using Phytoremediation Technologies to
Upgrade Waste Water Treatment in Europe”, Phytoremediation Technologies, Env Sci Pollut
Res 14 (7) 490 – 497 (2007), pp 496.
8. B. Van Aken, J. M. Yoon, C. L. Just, S. Tanake, L. Brentner, B. Flokstra & J.L. Schnoor, April
2005, “Phytoremediation: From the Scale Molecular to the Field”, Presented at the
International Phytotechnologies Conference April 20 2005, pp 8.

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References
9. Saber A. El-Shafai, Fatma A El-Gohary, Fayza A.Nasr. , N. .Peter van der Steen, Huub J.
Gijzen, March 2006, “Nutrient recovery from domestic waste water using a UASB-duckweed
pond system”. Bioresource Technology 98 798–807.
10. Peter Van Der Steen ,Asher Brenner ,Joost Van Buuren and M Gidoen Oron, June 1998,
“Post-Treatment Of UASB Reactor Effluent In An Integrated Duckweed And Stablization
Pond System”, Wat. Res. Vol. 33, No. 3, pp. 615-620.

29. QUESTIONS???

30. THANK YOU…