Bioremediation &Phytoremediation

Name –MALAYA GHOSHROLL NO-21PG-3RD SEMDEPT OF LSASSAM UNIVERSITY,SILCHAR

Bioremediation :

Bioremediation has been derived from two words “bios” meaning life and “remedy” meaning to solve problems together meaning to solve problems with the help of living organisms . Bioremediation is a waste management technology involved in the process of treating environmental pollution with the use of living organisms .It is mainly involved in removing contaminants,restoring contaminated sites and preventing further pollution .

Factors influencing bioremediation :

Microbial population Oxygen Nutients PH,Water Temperature ,etc

Types of bioremediation:

On the basis of type of degradation- Biotransformation. Biodegradation. Mineralization. On the basis of type of micro-organism used- Bacterioremediation Mycoremediation Phytoremediation Compost bioremediation

CONTD…..

On the basis of strategies involved – In-situ bioremediation Ex-situ bioremediation

In situ bioremediation :

In situ bioremediation is the treatment of contaminated material at the site.This process is usually recommended because it requires less materials to be moved and is less expensive . It is of two types viz- Intrinsic bioremediation Engineered in situ bioremediation

Techniques involved in bioremediation :

Bioventing Biosparging Biostimulation Bioaugmentation

Ex-situ bioremediation :

It involves removal of contaminated material to be treated elsewhere .However this technique is less time consuming as compared to those of traditional methods . On the basis of phases of contaminated materials under treatment they are of two types : Solid phase system Slurry phase system.

Solid phase system :

Solid phase system involves treatment of various solid wastes such as leaves , animal manures , agricultural waste , municipal solid waste , etc.It mainly involves the process of composting .

Solid phase system :

Slurry phase system :

Slurry phase system involves processing of contaminated soil or water through the use of engineered system like bioreactors so as to increase the rate of biodegradation .This system is actually a triphasic system involving three major components such as water , suspended particulate matter and air . The process involves three types of bioreactors- Aerated lagoons Low-shear airlift reactors Fluidized bed soil reactor.

Slurry phase treatment :aerated lagoons

Contd :low – shear airlift bioreactor

Reactions involved in bioremediation:

Aerobic reactions Anaerobic reactions

Aerobic metabolism :

Organic chemical (benzen

e)

oxygen

Co2+H2O+biomass

(increased number of bacteria )

Anaerobic metabolism :

Organic chemical (toluene)

Nitrate

CH4+N2+

H2O+Biomass

phytoremediation

Phytoremediation is defined as the in situ use of plants to stabilize , remediate and reduce or restore contaminated soil , water, sediments etc. The plants used for removal of polluting metal are able to accumulate heavy metal in their tissues and thus cause increase in dry weight of plant tissue.

Techniques of phytoremediation : Phytoextraction or Phytoaccumulation:It is the process by which the plants accumulate contaminants into the roots or other tissues thereby reducing the remediation cost by accumulating low level of contaminants from a widespread area . Eg- transgenic cotton wood with E.coli gene accumulates mercury , Indian mustard (Brassica juncea)accumulates Pb , S , Se,and such other metals. Phytotransformation or Phytodegradation:It refers to the breakdown of accumulated heavy metals and organics into less toxic or simpler forms by the metabolic activities of the microbes .as for example :metal Cr is reduced from hexavalent to trivalent Cr which is less mobile and non-carcinogenic form

Contd : Phytostabilization :Plants immobilize the heavy metal present in soil or ground water and accumulate in the root and precipitate within the root zone .eg –transgenic Arabidopsis carries a bacterial gene that transforms mercury into a gaseous state . Phytovolatilization :Plants take up the heavy metal from soil and volatilize them and ultimately releases to atmosphere via transpiration .

Contd :Rhizofiltration :It is a water remediation technique that involves uptake of contaminants such as heavy metals etc from wetlands and estuary areas.Rhizodegradation :It is the breakdown of contaminants through the activity of the existing in the rhizospere .This activity is due to the enzymes and proteins that are produced by the plants and the microbes such as yeast , bacteria , etc .it is actually a symbiotic relationship .

Advantages :

Bioremediation is useful to complete destruction of a wide variety of contaminants .Many compounds that are legally considered to be hazardous can to transformed to non –hazardous forms .

Instead of transferring contaminants from one medium to another environmental medium such as soil to water or such ,the technology helps in treating the contaminants on site itself.

It is proved to be less expensive than other technologies .

Disadvantages :

Bioremediation is limited only to those compounds that are biodegradable.

Biological processes are often highly specific .It mainly depends on the proper bacterial population and the various factors responsible for their proliferation

It is time consuming process.

Conclusion :Bioremediation is being successfully used to treat a wide range of contaminants in a broad range of environment .Contaminants which require bioremediation includes crude oil and refined petroleum products , halogenated solvents , pesticides, herbicides etc . By aiding natural selection and making small adjustments of the local environment to encourage growth of remediating microbes the process not only lowers the expenses but also very environment friendly .

References :

Alexander , Martin (1994 ).Biodegradation and Bioremediation , .New York : Academic press.

Sharma P.D , Ecology and Environment , 11th edition,345-373 Mina U , Kumar P , Life Sciences , Fundamentals and Practice II,5th

edition,580-581 Panda S.K , Talukdar A.D , Phytoremediation Technology , A review

Thank you