BIOREMEDIATION

SUMIT PATEL601101026

is defined as the process whereby organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below concentration limits established by regulatory authorities

This process is mainly carried out by biological agents like plants, microorganisms, fungi etc.

Based on the type of organisms used in bioremediation: 3 type.

Microbial Remediation(Microbes), Mycoremediation(fungi)

Phytoremediation(plant).

PRINCIPLES OF BIOREMEDIATION

Microbe Mediated BiodegradationMicrobe Mediated Biodegradation

1. Minor change in a molecule( dehalogenation)

2. Fragmentation3. Complete mineralization

Minor change in a molecule (dehalogenation)

Cl

Cl O CH2 COOH HOH

Cl

OH

HO O CH2 COOH

Cl is replaced with OH

FragmentationCl

Cl O CH2 COOH HOH

OH

HO OHHOCH2-COOH

MineralizationCl

Cl O CH2 COOH

CO22ClHOH

Completely converted into inorganic forms

Factors Affecting Bioremediation▪Microbial population that suites the environment that can biodegrade all of the contaminants.

▪Oxygen: enough to support aerobic biodegration.

▪Temperature: Appropriate temperatures for microbial growth (0-40).

▪pH: Best range is from 6.5 to 7.5

Compounds Can Be Treated Biologically Petroleum Hydrocarbons

GasolineDiesel FuelGasoline Additives such as MTBE

Polyaromatic HydrocarbonsCreosote

Chlorinated HydrocarbonsChlorinated Aliphatics: trichlorethyleneChlorinated Aromatics : PCB’s, Pentachlorophenol

ExplosivesRDX, TNT

Inorganics via Reduction to a Lower Valence Causing PrecipitationUranium, TechniciumSulfur and Sulfuric AcidAmmonia or Nitrate/NitritePhenol,benzene,DDT,tetrachloroethane.

Engineered Bioremediation

Intrinsic Bioremediation

Intentional changes

Simply allow biodegradation tooccur under natural conditions

Engineered bioremediation is also known as enhanced bioremediation.

Engineered bioremediation is a process that adds to or enhances the natural process of degradation.

An example of engineered bioremediation is to install wells to circulate fluids and nutrients to stimulate the microorganisms

is a natural attenuation process that leads to the decrease in contaminant levels in a particular environment due to unmanaged physical, chemical and biological processes.

- a bioremediation under natural conditions

In situ In situ BioremediationBioremediation(at the site)(at the site)

In situ In situ BioremediationBioremediation(at the site)(at the site)

Ex situ Ex situ BioremediationBioremediation(away from the site)(away from the site)

Ex situ Ex situ BioremediationBioremediation(away from the site)(away from the site)

Bioventing

involves supplying air and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.

• Biopiling

involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria.

• Bioaugmentationinvolves practice of adding specialized microbes or their enzyme preparation to polluted matrices to accumulate transformation or stabilization of specific pollutants

• Landfarminginvolves a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded.

• Composting

Traditional method to convert Traditional method to convert waste into household usable waste into household usable

materialsmaterialsinvolves combining contaminated soil with nonhazardous organic amendants such as manure or agricultural wastes. The presence of these organic materials supports the development of a rich microbial population and elevated temperature characteristic of composting.

In natural ecosystems, plants act as filters and metabolize substances generated by nature.

Evolutionary some plants have evolved the capacity to take up and accumulate selected metals in their shoots in levels that are toxic to ordinary plants

Some plants have developed symbiotic association with microbes that can degrade certain pollutants to compounds which are non-hazardous to the environment

Term coined in 1991

PhytoextractionPhytoextraction

1

PhytotransformationPhytotransformation

2

PhytostabilizationPhytostabilization

3

PhytodegradationPhytodegradation

RhizofiltrationRhizofiltration

4

5

5 types based on the fate of contaminants

Also called PhytoaccumulationA process used by the plants to accumulate contaminants into the roots and shoots or leaves.

Technique saves tremendous remediation cost by accumulating low levels of contaminants from a widespread area (usually metals)

Phytoextraction

Also called Phytodegradationrefers to the uptake of organic contaminants from soil, sediments, or water and, subsequently, their transformation to more stable, less toxic, or less mobile form.

Metal chromium can be reduced from hexavalent to trivalent chromium, which is a less mobile and non-carcinogenic form.

Leachable (permeate gradually) constituents are adsorbed and bound into the plant structure so that they form a stable mass of plant from which the contaminants will not reenter the environment

Also called rhizodegradationis the breakdown of contaminants through the activity existing in the rhizosphere.

Due to the presence of proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi.

a symbiotic relationship that has evolved between plants and microbes

Plants provide nutrients necessary for the microbes to thrive, while microbes provide a healthier soil environment.

is a water remediation technique that involves the uptake of contaminants by plant roots

used to reduce contamination in natural wetlands and estuary areas

The wide part of a river where itnears the sea; fresh and salt water mix

Plant used in Phytoremediation

Bamboo family – accumulates silica in its stalk and nitrogen as crude protein in its leaves Indian mustard (Brassica juncea) - accumulates selenium, sulfur, lead, chromium, cadmium, nickel, zinc, and copper Chinese ladder fern (Pteris vittata) - accumulates arsenic Tomato and alpine pennycress - accumulates lead, zinc cadmium Poplar - used in the absorption of the pesticide, atrazine .

The major advantages of phytoremediation are as follows

The cost of the phytoremediation is lower than that of traditional processes both in-situ and ex- situ.

ii) The plants can be easily monitored.iii) The possibility of the recovery and re-use of valuable products.iv) It uses naturally occurring organisms and preserves the natural state of the

environment.v) The low cost of phytoremediation (up to 1000 times cheaper than

excavation and reburial) is the main advantage of phytoremediation.

Advantages of Bioremediation

•Lower cost than conventional technologies.•Contaminants usually converted to innocuous products.•Contaminants are totally destroyed, not simply transferred to different environmental media.• potentially allowing for continued site use.•Relative ease of implementation.

Conclusion Bioremediation is a powerful tool available to clean up contaminated sites.

Bioremediation occurs when there are microorganisms present that can biodegrade the given contaminant and the necessary nutrients such as nitrogen, phosphorus, electron acceptors, and trace elements.

This process can be aerobic or anaerobic depending on the microorganisms and the electron acceptors available.

This process may be natural (intrinsic bioremediation) or it may be enhanced by man (engineered bioremediation). Regardless of which aspect of bioremediation that is used; this technology offers an efficient and cost effective way to treat contaminated ground water and soil.

Its advantages generally outweigh the disadvantages, which is evident by the number of sites that choose to use this technology and its increasing popularity.

References:www.slsc.org/uploadedFiles/Bioremediation.pdf www.ku.edu.np/kuset/vol8_no1/20_Bijay_Thapa.pdf www.epa.gov/swertio1/download/citizens/bioremediation.pdf

www.wm.com/about/community/pdfs/Bioremediation.pdf http://waterquality.montana.edu/docs/methane/Donlan.shtml

astonjournals.com/manuscripts/Vol2010/GEBJ-3_Vol2010.pdf

esd.lbl.gov/files/about/staff/.../reprints_ActaMicrobioPol50_205.pdf

http://www.in.gov/idem/files/remediation_tech_guidance_bioremediation.pdf