PHYTOREMEDIATION

DAYAL KURIAN VARGHESE

OVERVIEW

INTRODUCTION OF PHYTOREMEDIATION

NEED FOR THE NEW

REMEDIATION TECHNIQUE

VARIOUS PHYTOREMEDIATION PROCESSES

PHYTOREMEDIATION BY AQUATIC PLANTS

ADVANTAGES AND DISADVANTAGES

CONCLUSION

INTRODUCTION

Phytoremediation can be defined as the use of green plants to remove the contaminants from the environment or to render them harmless.

“Phyto”= Plant (in Greek)

“Remediare”= To remedy (in Latin)

NEED FOR THE NEW REMEDIATION

TECHNIQUE

Microbial/ Biological Measures

These approaches are ecological and economically sound butphysical removal/ cleaning up of contaminants does not occursas contaminants remain in the soil system

Chemical Measures

Chemical extraction procedures have been suggested but they are not cost effective.

So, these constraints have forced the researcher to think of using plants for cleaning up their own support system which will eco-friendly and cost effective. This new approach is “Phytoremediation”.

VARIOUS PHYTOREMEDIATION

PROCESSES

Phytoextraction

Rhizofiltration

Phytostabilization

Phytotransformation

Rhizosphere Bioremediation

PHYTOEXTRACTION

Phytoextraction uses

plants or algae to remove

contaminants from soils,

sediments or water into

harvestable plant biomass.

The main advantage of

phytoextraction is

environmental friendliness.

PHYTOSTABILISATION

Phytostabilization is the use of plants to prevent the

migration of contaminants through control of the hydraulic

gradient or by reinforcing the soil structure.

PHYTOTRANSFORMATION

chemical modification of

environmental substances

as a result of

plant metabolism resulting

in their inactivation,

degradation

(phytodegradation) or

immobilization

(phytostabilization).

RHIZOFILTRATION

Filtering water through a

mass of roots to remove

toxic substances or

excess nutrients.

The pollutants remain

absorbed in or adsorbed to

the roots.

Chernobyl - sunflowers were grown inradioactively contaminated pools

RHIZOSPHERE BIOREMEDIATION

Enhancement of soil

microbial activity for

the degradation of

contaminants, typically

by organisms that

associate with roots.

Rhizosphere = soil +

root + microbes.

Also known as

Phytostimulation.

PHYTOREMEDIATION BY AQUATIC

PLANTS

Aquatic plants are those plants living in and adapted toaquatic environments, which can only grow in water orpermanently saturated soil.

Eurasian Watermilfoil (Myriophyllum spicatum)

Water Hyacinth (Eichhornia crassipes )

Duckweed (Lemna trisulca L.)

Fool's Watercress (Apium nodiflorum)

Water Hyacinth

Floating plant with broad ,thick,and glossy leaves that the plantbody can grow as much as 1m high.

Able to phytoaccumulate metalpollutants contain Ag, Pb, Cd andZn in municipal and agriculturalwastewater.

Known as one of the plants withfastest growth rate that can doublepopulation in 2 weeks.

High invasive potential.

Case Study: Removal of Cadmium and Zinc by Water Hyacinth

The stock solution was prepared in distilled water with analytical grade

CdCl2. 2½ H2O and ZnSO4.7H2O which was later diluted as required. The

plants were maintained in tap water with concentrations of 0.5, 1, 2, 4 mg/L

of Cd and 5, 10, 20, 40 mg/L of Zn.

The test durations were 0 (two hours), 4, 8 and 12 days.

Relative growth, metal accumulation, and bioconcentration factor (BCF)

are evaluated.

Relative growth (above) and BCF (below)

Zn

CdCd

Zn

Cd

Zn

(Lu et al., 2004)

Relative plant growth Metal Accumulation BCF

Duckweed

Has a very simple structure that

lacks obvious stems or leaves, with

small plate-shaped structure floating

on water surface.

Reproduction is mainly rely on

asexual budding.

High pollutant removal potential

due to small size, fast growth, and

easy to cluture.

(Kara and Kara, 2004)

The duckweed obtained from

natural lake was acclimatized to

laboratory conditions for one week

before starting research.

Solution of Cadmium was

prepared using Cd(NO3)2 and

contact with plant sample for

different length.

After absorption, water samples

were analyzed by AAS at 228.8nm.

Case Study: Removal of Cadmium by Duckweed

Cd removal efficiencies

(Kara and Kara, 2004)

ADVANTAGES AND DISADVANTAGES

Advantages Disadvantages

Cost effective when compared to other

more conventional methods.

Slow rate and difficult to achieve

acceptable levels of decontamination.

“natural” method, more aesthetically

pleasing.

Possibility of contaminated plants

entering the food chain.

minimal land disturbance. Possible spread of contaminant

through falling leaves.

reduces potential for transport of

contaminants by wind/soil erosion.

Trees and plants require care.

multiple contaminants can be removed

with the same plant.

Contaminant might kill the tree.

It is one of the least harmful method. Degradation product could be worse

than original contaminant.

The possibility of recovery and reuse ofvaluable metals.(Phyto mining)

Only surface soil (root zone) can be

treated.

Cleanup takes several years.

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.

REFERENCES:

Majeti Narasimha Vara Prasad,et al, “Metal hyperaccumulation in plants -Biodiversity prospecting for phytoremediation technology”, Electronic Journal of Biotechnology 6(3),2003,450 -458.

Yeşim Kara,et al, ” Removal of Cadmium from Water Using Duckweed (Lemna

trisulca L.)”, International Journal Of Agriculture & Biology 4,2005,660-662.

Angela Pierre Vitória,et al, ” Structural and Ecophysiological Alterations of the Water Hyacinth [Eichhornia crassipes (Mart.) Solms] Due to Anthropogenic Stress in Brazilian Rivers”, Brazilian Archives Of Biology And Technology 54(5),2011, 1059-1068.

Mesania Rizwana,et al, ” Phytoremediation of Textile Waste Water Using Potential Wetland Plant: Eco Sustainable Approach”, International Journal of Interdisciplinary and Multidisciplinary Studies (IJIMS) 1(4),2014,130-138.

REFERENCES(CONTD.)

Divya Singh,et al, “Phytoremediation of lead from wastewater using aquatic

plants”, Journal of Agricultural Technology 8(1),2012,1-11.

Honey Aggarwal,et al, “Phytoremediation of some heavy metals by agronomic

crops”, Developments in Environmental Science 5,2007,79-98.

Hiromichi Morikawa,et al, “Basic processes in phytoremediation and some

applications to air pollution control”, Chemosphere 52,2003, 1553-1558.

Hongyu Wang,et al, “An Application of Phytoremediation to River Pollution

Remediation”, Procedia Environmental Sciences 10 ,2011 ,1904 – 1907.

T H A N K S !

Any questions?