phytoremediation

1. LAND CONTAMINATION AND
REMEDIATION(PHYTOREMEDIATION)
Submitted to: Prof. R.K.SRIVASTAVA
Presented by: VIMLESH KUMAR VERMA
DEPARTMENT OF CIVIL ENGINEERING MNNIT,
ALLAHABAD

2. CONTENT
 SOIL CONTAMINATION
 NATURAL AND ANTHROPOGENIC ACTIVITIES
 CAUSES BY CONTAMINATION
 SOIL REMEDIATION
 PHYTOREMEDIATION
 FORMS OF PHYTOREMEDIATION
 ADVANTAGES AND DISADVANTAGES OF
PHYTOREMEDIATION
 CONCLUSIONS
 REFERENCES

3. Soil contamination
 When the concentration of chemicals, nutrients or elements in the soil
becomes more than it normally as a result of human action. If this
contamination goes on to harm living organisms, we can call it
 Soil contamination or soil pollution as part of land degradation is
by the presence of xenobiotic (human-made) chemicals or other
alteration in the natural soil environment.
 It is typically caused by industrial activity, agricultural chemicals, or
improper disposal of waste.
 The most common chemicals involved
are petroleum hydrocarbons, polynuclear aromatic hydrocarbons (such
as naphthalene and benzo(a) pyrene, solvents, pesticides, lead, and
other heavy metals. Contamination is correlated with the degree
of industrialization and intensity of chemical usage.

4. Natural and anthropogenic activities
Anthropogenic:
 Accidental spills and leaks during storage (transport or use of
chemicals )
 Mining activities (crushing and processing of raw materials )
 Agricultural activities (spread of herbicides/pesticides/ and
fertilizers) Transportation activities (e.g., vehicle emissions)
 Dumping of chemicals (such as illegal dumping)
 Storage of wastes in landfills (which may leak to groundwater
or generate polluted vapors)

5. Natural activities:
 Natural accumulation of compounds in soil: (due to
imbalances between atmospheric deposition and
away with precipitation water)
 Natural production in soil under certain environmental
conditions: (natural formation of soil in the presence of a
chlorine source, metallic object and using the energy
generated by a thunderstorm)
 Leaks from sewer lines into subsurface: (e.g. adding
chlorine which could generate such as chloroform)

6. Causes by contamination:
 Reduction in soil fertility
 Imbalance is the flora and fauna of the soil.
 Salinity increases in the soil making it unfit for
 Crops grown on polluted soil cause health problems on
consumption Soil pollution creates toxic dust.
 Foul odour due to chemicals and gases can lead to
problems like headaches, nausea, etc.
 Pollutants in soil causing death of many soil organisms
 Accidents in goods transport

7. Soil Remediation- Types of Techniques
 Excavate soil and take it to a disposal site away from ready pathways for
human or sensitive ecosystem contact. This technique also applies to
dredging of bay muds containing toxins.
 Aeration of soils at the contaminated site (with attendant risk of
creating air pollution).
 Thermal remediation by introduction of heat to raise subsurface
temperatures sufficiently high to volatize chemical contaminants out of
the soil for vapor extraction. Technologies include electrical resistance
heating (ERH).
 Bioremediation, involving microbial digestion of certain organic
chemicals. Techniques used in bioremediation include landfarming,
biostimulation and bioaugmentating soil biota with commercially
available microflora.

8.  Extraction of groundwater or soil vapor with an
active electromechanical system, with subsequent stripping
of the contaminants from the extract.
 Containment of the soil contaminants (such as by capping
paving over in place).
 Phytoremediation, or using plants (such as willow) to extract
heavy metals.
 Remediation of oil contaminated sediments with self-
collapsing air microbubbles

9. PHYTOREMEDIATION:
phyto = plant, and
remedium = restoring balance.
defined as “the efficient use of plants to remove, detoxify or
immobilize environmental contaminants in a growth matrix (soil,
water or sediments) through the natural biological, chemical or
physical activities and processes of the plants”

10.  In recent years, phyto accumulation/ phyto extraction, i.e., the use of
plants to cleanup soils contaminated with non-volatile hydrocarbons and
immobile inorganics is showing promises as a new method for in situ
cleanup of large volumes of low to moderately contaminated soils.
 Plants can be used to remove, transfer, stabilize and/or degrade heavy
metal soil contaminants.
 The technique was first adapted to constructed wetlands, reed beds and
floating plant systems for the treatment of contaminated ground and
waste waters for years.
 Current efforts now focus on expanding the phytoremediation strategy to
address contaminated soils and air pollutants in an attempt to preserve
the biodiversity of soil and its biota.

11. HOW DOES PHYTOREMEDIATION WORK ?
Phytoremediation is an in situ remediation technology
utilizes the inherent abilities of living plants.
The mechanisms and efficiency of phytoremediation
depend on the type of contaminant, bioavailability and
properties.
The root system provides an enormous surface area that
absorbs and accumulates the water and nutrients
for growth, as well as other non-essential contaminants.

12. FORMS OF PHYTOREMEDIATION

13. Various phytoremediation processes:
 Phytoextraction
 Phytostabilization
 Phytotransformation
 Phytostimulation
 Phytovolatilization
 Rhizofiltration

15. THE USE OF PHYTOREMEDIATION TO TREAT ORGANIC
CONTAMINANTS
 Phytodegradation
 Rhizodegradation
 Phytovolatilization

16. PHYTODEGRADATION
 Also called as Phytotransformation.
 Degradation of complex organic molecules to simple
molecules or the incorporation of these molecules into
tissues.
 Plants contain enzymes that catalyze and accelerate
reactions.
 Uptake of contaminants depend on hydrophobicity ,
solubility and polarity.

17. RHIZODEGRADATION
 Also called phytostimulation or plant assisted
bioremediation/degradation.
 Symbiotic relationship
 Natural substances released by the plant roots – sugars,
alcohols, and acids – contain organic carbon that
food for soil microorganisms and the additional nutrients
enhance their activity.
 Additionally, the rhizosphere substantially increases the
surface area where active microbial degradation can be
stimulated.

19. Example :
The number of beneficial bacteria
increased in the root zone of
hybrid poplar trees and enhanced
the degradation of BTEX, organic
chemical, in soil.

20. PHYTOVOLATILIZATION
 Uptake and transpiration of a contaminant by a plant, with
release of the contaminant or a modified form of the
contaminant from the plant to the atmosphere.
 Phytovolatilization has mainly been applied to
groundwater, but it can be applied to soil, sediments, and
sludge.
 Example : Poplar trees

21.  Because phytovolatilization
involves the transfer of
contaminants to the atmosphere,
the impact of this contaminant
transfer on the ecosystem and on
human health needs to be
addressed.
 Climatic factors such as
temperature, precipitation,
humidity, insolation, and wind
velocity can affect transpiration
rates.

22. THE USE OF PHYTOREMEDIATION TO TREAT METAL
CONTAMINANTS
 Phytoextraction
 Rhizofiltration
 Phytostabilization

23. PHYTOEXTRACTION
 Also called phytoaccumulation, refers to the uptake of
metals from soil by plant roots into above-ground
portions of plants.
 Certain plants, called hyperaccumulators, absorb
unusually large amounts of metals in comparison to
other plants. E.g. . Thlaspi rotundifolium
 After the plants have been allowed to grow for some
time, they are harvested and either incinerated or
composted to recycle the metals.
 Benefit is that the contaminant is permanently
removed from the soil.

24. Example :
 Detroit lead contaminated site
was removed with Sunflower and
Indian Mustard.
 Arsenic, using the Sunflower, or
the Chinese Brake fern , a
hyperaccumulator. Chinese Brake
fern stores arsenic in its leaves.
 Mercury, selenium and organic
pollutants such as
polychlorinated biphenyls (PCBs)
have been removed from soils
transgenic plants .

25. RHIZOFILTRATION
 Rhizo means root.
 Adsorption or precipitation onto plant roots, or
into the roots of contaminants that are in solution
surrounding the root zone, due to biotic or abiotic
processes.
 Exploited in groundwater, surface water, or wastewater for
removal of metals or other inorganic compounds.
 Rhizofiltration first results in contaminant containment, in
which the contaminants are immobilized or accumulated
on or within the plant. Contaminants are then removed by
physically removing the plant.

26. Examples :
 Sunflower, Indian mustard, tobacco, rye, spinach, and corn
have been studied for their ability to remove lead from
water, with sunflower having the greatest ability.
 Sunflowers were successfully used to remove radioactive
contaminants from pond water in a test at Chernobyl,
Ukraine.
 Rhizofiltration can be used for Pb, Cd, Cu, Ni, Zn, and Cr,
which are primarily retained within the roots.

27. PHYTOSTABILIZATION
 This is also referred to as in-place inactivation.
Phytostabilisation is the use of certain plant species to
immobilise contaminants in the soil and groundwater
through absorption and accumulation by roots, adsorption
onto roots, or precipitation within the root zone of plants
(rhizosphere)
 It is primarily used for the remediation of soil, sediment,
sludge.
 Reduces mobility and prevents migration.

28.  Change in pH , metal solubility and mobility
 Used to re establish vegetation cover at sites where natural
vegetation fails to survive due to high metals concentrations
in surface soils or physical disturbances to surface materials.
 Example : Phytostabilization using metal-tolerant grasses is
being investigated for large areas of Cd- and Zn-
contaminated soils at a Superfund site in Palmerton, PA.

30. ADVANTAGES
 “nature” method, more aesthetically pleasing.
 The cost of the phytoremediation is lower than that of
traditional processes both in situ and ex situ.
 The plants can be easily monitored.
 The possibility of the recovery and re-use of valuable
 Minimal land disturbance.
 Reduces potential for transport of contaminants by wind,
reduces soil erosion.
 Multiple contaminants can be removed with the same plant.

31. DISADVANTAGES
 Limited to the surface area and depth occupied by the
 Slow growth and low biomass require a long-term
commitment
 Not possible to completely prevent the leaching of
contaminants into the groundwater
 The survival of the plants is affected by the toxicity of the
contaminated land and the general condition of the soil.
 Bio-accumulation of contaminants, especially metals, into
plants which then pass into the food chain, from primary
level consumers upwards and/or requires the safe disposal
the affected plant material.

32. Conclusion
• Although much remains to be studied, phytoremediation will clearly
play some role in the stabilisation and remediation of many
contaminated sites.
• The main factor driving the implementation of phytoremediation
projects are low costs with significant improvements in site aesthetics
and the potential for ecosystem restoration.
• Phytoremediation has been tested by various green house and pilot-
scale field experiments in the USA and Europe.
• Most have been found in contaminated areas of temperate Europe
the USA, New Zealand and Australia. Besides the limited distribution of
hyper accumulators in the wild, such plants also tend to be
specific. No plant species has yet been found that will demonstrate a
wide spectrum of hyper accumulation.

33. THANKU