Phytoremediation
Dr. Aparna M. B
Bioremediation
• Bioremediation
– any process wherein a biological system, living or
dead, is employed for removing environmental
pollutants
– from air, water, soil, flue gasses, industrial
effluents etc.,
– in natural or artificial settings.
What is Phytoremediation?
• Phytoremediation
– is a bioremediation process
– uses various types of plants to
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remove,
transfer,
stabilize, and/or
destroy contaminants in the soil and groundwater.
Phyto = plants
Remediation = restoring balance
Types of Phytoremediation
(mechanisms)
• phytoextraction,
• phytostabilization,
• phytovolatilization,
• phytodegradation,
• phytodesalination,
• rhizofiltration,
• rhizodegradation
Phytoextraction
• Using plants to
transport and
concentrate metals
from the soil
• into the harvestable
parts of roots and
above-ground shoots
• the harvestable parts, rich in accumulated metals, can be easily
and safely processed by drying, ashing or composting.
• Some extracted metals can also be reclaimed from the ash,
generating recycling revenues
• Plants – Indian mustard (Brassica juncea),Sunflower (Helianthus annuus), Ragweed
Pollutants – Arsenic, Cadmium , Zinc, Lead
Phytostabilization
• the use of metal-tolerant
plant species to immobilize
heavy metals belowground
• decrease their
bioavailability,
• preventing their migration
into the ecosystem
Pollutants :- Cadmium, Zinc,
• reducing the chance of
Copper, Hassium(Hs)
metals entering into the Plants :-Hybrid poplars, Brassica
juncea
food chain
Phytovolatilization
• the uptake of
contaminants by plant
roots and its conversion
to a gaseous state, and
release into the
atmosphere.
use of plants to absorb heavy metal pollutants and transform
them into volatile, less hazardous chemical species via
transpiration.
• Pollutants :- Selenium, Mercury, Arsenic and Chlorinated
solvents
• Plants :- Alfalfa,Arabidopsis thaliana, Poplars.
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Phytodegradation (Phytotransformation)
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the degradation of organic
contaminants
directly, through the release of
enzymes from roots,
or through metabolic activities
within plant tissues.
Pollutant :- Organic compounds,
Phenols, Herbicide, Chlorinated
solvents
Plants :- Black Willow, Hybrid
poplars
• organic contaminants are taken up by roots
• metabolized in plant tissues to less toxic substances.
• Some enzymes break down ammunition wastes (explosives),
chlorinated solvents or herbicides.
Phytodesalination
• involves the extraction of salt and NaCl from
water and soils by using plants (halophytes)
• which can extract salt and keep it in the
leaves.
• a sustainable approach in the field
of agriculture in saline lands
• and it will also be helpful for the recovery of
salt-affected lands.
Rhizofiltration,
• Rhizofiltration is a form of
phytoremediation
• involves filtering contaminated
groundwater, surface water, and
wastewater
• through a mass of roots to remove
toxic substances or excess
nutrients.
• Both absorption and adsorption of
the contaminants on the root
takes place during the process.
• Pollutants :- Cadmium, Copper,
Zinc, Nickel
• Plants :-Tobacco, Rye, Spinach,
Brassica juncea, Corn
Rhizodegradation (Phytostimulation)
• Phytostimulation also called as
rhizodegradation
• is the breakdown of the contaminants in the
rhizosphere
• through microbial activity that is enhanced by
the presence of plant roots.
• It is a much slower process than
phytodegradation.
• The type of plant utilized for
phytoremediation (metallophytes) is
categorized as
– metal indicators,
– metal excluders, and
– metal hyperaccumulators.
• Phytoremediation consists of reducing
pollutant concentrations in contaminated
soils, water or air with plants.
• Plants take up, degrade or eliminate
– metals,
– pesticides,
– solvents,
– explosives,
– crude oil and its derivatives
– and various other contaminants from the media
that contain them
Advantages of phytoremediation
• Cost effective
• Suited to remediation of large areas of
soil
• It is environment friendly
• Sites are aesthetically pleasing
• Low maintenance
• No need of noisy and costly equipments