Phytoremediation kust

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Phytoremediation presentation by jehanzeb khan

Transcript of Phytoremediation kust

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Presented By Jehanzeb khan PhD 1st Semester Department of Botany [email protected]

Course AdvisorDr Aziz UllahAssistant Professor Department of BotanyKUST

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SYNTHETIC POLLUTANTS

PHYTOREMEDIATION

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OVERVIEW Introduction of Phytoremediation1. Application2. Various phytoremediation processes3. Role of genetics4. Hyperaccumulators 5. Phytoscreening6. Advantages and limitations

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PHYTOREMEDIATION

The use of plants which lessen the environmental problem without the need to dig up the contaminant material and dispose of it elsewhere.

phyto = plantremedium = restoring balance

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 Application Phytoremediation may be applied

wherever the soil or stagnant water environment has become polluted or is suffering ongoing constant pollution.

Examples where phytoremediation has been used successfully include the restoration of abandoned metal-mine workings, reducing the impact of contaminants in soils, water, or air.

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How does Phytoremediation work? First process is Phytodegradation, which is when a plant

takes in TCE(Trichloroethylene) and degrades it into CO2 and chlorine before released into the atmosphere.

Another process is phytovolatilization which is when some chemicals are taken in through the xylem and converted into a gas through the stomata of the plant.

When plants go through these processes they leave chemicals in stem for easy collection.

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Process

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Various phytoremediation processes

A range of processes mediated by plants or algae are useful in  treating environmental problems: 

1. Phytoextraction2. Phytostabilization3. Phytotransformation4. Phytostimulation 5. Phytovolatilization 6. Rhizofiltration

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Phytoextraction Plant  roots  uptake  metal  contaminants 

from the soil and translocate them to their above soil tissues

Once the plants have grown and absorbed the  metal  pollutants  they  are  harvested and disposed off safely

This  process  is  repeated  several  times  to reduce contamination to acceptable levels

Hyper accumulator plant species are used on  many  sites  due  to  their  tolerance  of relatively extreme levels of pollution

Avena sp. , Brassica sp.Contaminants removed: Metal  compounds  that  have  been 

successfully  phytoextracted  include  zinc, copper, and nickel

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Phytostabilisation

Vegetation holds contaminated soils in place Root system and low growing vegetation

prevent mechanical transportation of pollutants

from wind and erosion. Trees transpire large quantities of water

(more than 15 gal/day) so pumping action

prevents contaminants from migration into the

water table (leaching).

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Phytotransformation chemical modification of environmental substances as a

result of plant metabolism resulting in their inactivation, degradation (phytodegradation), or immobilization (phytostabilization).

Trichloroethylene (TCE), a widespread ground

water contaminant, transformed to less toxic

metabolites by using hybrid poplar tree. Air Force facility in Texas using cottonwoods to

treat a large ground water cloud of TCE. EPA research lab using parrot feather (a

common aquatic weed) for TNT treatment.

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Phytostimulation 

Phytostimulation is the process where root released compounds enhance microbial activity in the rhizosphere.

Rhizosphere = soil + root + microbes Symbiotic relation

Enhanced rhizosphere biodegradation Phytostimulation Plant assisted bioremediation

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Continued…..

Sugars, alcohols, and organic acids act as carbohydrate sources for the soil microflora and enhance microbial growth and activity.

Act as chemotactic signals for certain microbes. The roots also loosen the soil and transport water to the

rhizosphere thus enhancing microbial activity Digest organic pollutants such as fuels and solvents,

producing harmless products

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Phytovolatilization  Plants uptake contaminants which are water soluble and

release them into the atmosphere as they transpire the water

The contaminant may become modified along the way,

as the water travels along the plant's vascular system from the roots to the leaves, whereby the contaminants evaporate into the air surrounding the plant

Poplar trees volatilize up to 90% of the TCE they absorb 

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Rhizofiltration

 filtering water through a mass of roots to remove toxic substances or excess 

The contaminants are either adsorbed onto the root surface or are absorbed by the plant roots

1995, Sunflowers were used in a pond near Chernobyl

Plants used for

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Chernobyl -sunflowers were grown in radioactively contaminated pools

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Role of genetics Genetic engineering is a powerful method for

enhancing natural Phytoremediation

capabilities, or for introducing new capabilities

into plants. Example, genes encoding a

nitroreductase from a bacterium were inserted

into tobacco and showed faster removal of TNT

and enhanced resistance to the toxic effects of

TNT

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Hyperaccumulators

A plant that absorbs toxins, such as heavy metals, to a greater concentration than that in the soil in which it is growing

A number of interactions may be affected by metal hyperaccumulation:

mutualism (including mycorrhizae)

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Phytoscreening

 Plants are able to translocate and accumulate particular types of contaminants:

plants can be used as biosensors of subsurface contamination

 Phytoscreening may lead to more optimized site investigations and reduce contaminated site cleanup costs

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Advantages

Cost effective when compared to other more

conventional methods. “natural” method, more aesthetically pleasing. minimal land disturbance. reduces potential for transport of

contaminants by wind, reduces soil erosion hyper-accumulators of contaminants mean a

much smaller volume of toxic waste. multiple contaminants can be removed with the

same plant.

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Disadvantages Slow rate and difficult to achieve acceptable

levels of decontamination. Possibility of contaminated plants entering

the food chain. Possible spread of contaminant through

falling leaves. Trees and plants require care. Contaminant might kill the tree. Degradation product could be worse than

original contaminant. Only surface soil (root zone) can be treated

Cleanup takes several years

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Conclusion

Although much remains to be studied, Phytoremediation will clearly play some role in the

stabilization 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.

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Questions & Answers

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Thank you