• Essential Factors for microbial Bioremediation

Bioremediation

Objectives

• Bioremediation

• How it works?

• Essential Factors for microbial Bioremediation

• Bioremediation Methods & Types

• Microbes involved in Bioremediation

• Advantages & Disadvantages of Bioremediation

• Application of Bioremediation

• Some Bioremediation related technologies.

What is Bioremediation?

•

"Remediate" means to solve a problem, and "bio-

remediate" means to use biological organisms to solvean environmental problem such as contaminated soil or

groundwater.

•

Bioremediation means to use a biological remedy to abate or clean up contamination.

•

Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminatedsite.

•

According to the EPA, bioremediation is a “treatment that uses naturally occurring organisms to break down

hazardous substances into less toxic or non toxic

substances”.

What is Bioremediation?

•

Bioremediation is the a biological degrading processes for the treatment of contaminated soils, groundwater and/or sediments, relying on microorganisms including bacteria and/or fungi to use the contaminant(s) as a food source with resulting degradation of the contaminant .

•

Microorganisms used to perform the function of bioremediation are known as bioremediators.

•

Bioremediation is one of the most economic remedial techniques presently available for

treating most organic fuel based contaminants such as coal tars and liquors, petroleum and

other carcinogenic hydrocarbons such as benzene and naphthalene, and some inorganics .

Organisms Pollutants

Environments

Inorganic Organic

Solid Liquid

Gas

Soil Water

Air

Microorganisms Plants

Enzymes

How Does It Work?

• Waste material is examined & certain bacteria are isolated based on their efficacy at digesting and converting the waste.

• Indigenous or local bacteria is to beused!

• The bacteria then go through several steps of cultures and process for performance testing.

• The suitable bacteria are placed back in the waste environment.

• They grow & thrive & in the process digest &

convert the waste into Carbon dioxide & water.

• The right temperature, nutrients, and food also must be present.

ESSENTIAL FACTORS FOR MICROBIAL BIOREMEDIATION

Factor Desired Conditions

Microbial population

Oxygen

Water

Suitable kinds of organisms that can biodegrade all of the contaminants

Enough to support aerobic biodegradation (about 2% oxygen in the gas phase or 0.4 mg/liter in the soil water)

Soil moisture should be from 50–70% of the water holding capacity of the soil

Nutrients Nitrogen, phosphorus, sulfur, and other

nutrients to support good microbial growth

Temperature pH

Appropriate temperatures for microbial growth (0–40˚C)

Best range is from 6.5 to 7.5

Bioremediation

In situ

-At the site

-treatment of contaminated material in place

-Ex – Benzene, Toluene, TNT,2,4-D -only certain types of soils can be

bioremediated in-situ

-complete degradation is often difficult to achieve

Ex Situ

-Away from site

-Techniques involve physical removal of the contaminated material for treatment

process

-Ex- Bio-piles, soil treatment unit, Compost pile , Windrows etc. &

-use of bioreactors to process the material in a highly controlled environment.

TYPES OF BIOREMEDIATION :

1. Biostimulation 2. Bioaugmentation 3. Intrinsic Bioremediation

• The method in which bacteria are motivated to start the process of bioremediation.

• In this method, first the experts release nutrients and other

important substances in the soil where there is need or removing the contaminants.

• These are in the form of gas or liquid. It increases the growth of microbes in that area.

• As a result bacteria and other microorganisms remove the

contaminants quickly and efficiently.

• Microorganisms that can clean up a particular contaminant are

added to the contaminated soil and water.

• Bioaugmentation is more

commonly and successfully used on contaminants removed from the original site, such as

municipal waste water treatment facilities.

• Process takes place in soil and water because these two places are always full of contaminants and toxins.

• This process is also called as natural attenuation.

• Also means use of the

microorganisms to remove the harmful substances from soil and water.

• Especially those sites are treated with this method, which are underground, for example underground petroleum tanks.

Bioremediation by Bacteria

Genetically engineered bacteria (Pseudomonas)

Bioremediation by Fungi

Candida can degrade formaldehyde.

with plasmid producing enzymes todegrade octane Gibeberella can degrade cyanide.

and many different organic compounds from crude White rot fungi can degrade organic

oil. pollutants in soil and effluent and decolorize

• A selected list of genetically engineered kraft black liquor, e.g.Phanerochaete

microorganisms. chrysosporium can produce aromatic

mixtures with its lignolytic system.

Pentachlorophenol,dichlorodiphenyltrichloro ethane (e.g. DDT), even TNT (trinitrotoluene) can be degraded by white rot fungi.

➢ METABOLIC EFFECT OF MO’S ON XENOBIOTICS:

¤ Detoxification ¤ Activation

¤ Degradation ¤ Conjugation

Advantages:

• Low cost.

• Minimal site disruption.

• Simultaneous treatment of contaminated water and soil.

• Minimal exposure of public & site personnel.

• Useful for the complete destruction of awide variety of contaminants.

• Can often be carried out on site, often without causing a major disruption of normal activities

• Can prove less expensive than other

technologies that are used for cleanup of hazardous waste.

Disadvantages:

• Time consuming.

• Seasonal variation.

• Problematic addition of additives.

• Limited to those compounds that are biodegradable.

• Not all compounds are susceptible to rapid and complete degradation.

• There are some concerns that the products of biodegradation may be more persistent or toxic than the parent compound.

• difficult to extrapolate (deduce) from bench and pilot-scale studies to fullscale field

operations.

• Biological processes are often highly specific.

microbial populations, suitable

environmental growth conditions, and

appropriate levels of nutrients and

contaminants.

Applications of Bioremediation

Bioremediation is used in following ways:

❖

Bioremediation of contaminated soil

❖

Bioremediation of aquifer

research

❖

Bioremediation of marine oil

pollutants

Govt.(various

❖

Bioremediation of industrial waste

their experiments

Slurry-phase bioremediation is useful too

but only for small amounts of

contaminated soil.

Composting can be used to degrade

household wastes.

Bioremediation of Contaminated Soil

In-situ bioremediation of soil:

•

Allows treatment of a large volume of soil at once.

•

Mostly effective at sites with sandy soils.

•

Can vary depending on the method of

supplying oxygen or electron donors to the organisms that degrade the contaminants.

•

Three commonly used in-situ methods include:

➢ Bioventing

➢ Injection of hydrogen peroxide or oxygen

releasing compound (ORC) for aerobic treatment

➢ Injection of HRC for anaerobic treatment

Ex-situ Bioremediation of soil:

• Involves excavation of the

contaminated soil and treating in a treatment plant located on the site or away from the site.

• This approach can be faster, easier to control, and used to treat a wider range of contaminants and soil types than in- situ approach.

• Ex-situ bioremediation can be implemented as:

➢ Slurry-phase bioremediation, or

➢ Solid-phase bioremediation

Contained Solid Phase

Compost

ing Land

farming

Bioremediation related technologies

• Phytoremediation -bioremediation through the use of plants that mitigate the environmental problem without the need to excavate the contaminant material and dispose of it elsewhere.

• Bioventing -an in situ remediation technology that uses microorganisms to biodegrade organic constituents in the groundwater system.

• Bioleaching -the extraction of metals from their ores through the use of livingorganisms.

• Landfarming -an ex-situ waste treatment process that is performed in the upper soil zone or in biotreatment cells.

• Bioreactor -any manufactured or engineered device or system that supports a biologically active environment.

• Vermicomposting -using various worms, usually red wigglers, white worms, and other earthworms to create a heterogeneous mixture of decomposing vegetable or food waste, bedding materials, and vermicast.

• Rhizofiltration -is a form of phytoremediation that involves filtering water through a mass ofroots to remove toxic substances or excess nutrients.

References

•

Microbial Ecology by Atlas & Bartha

•

Various Webpages including:

• Wikipedia

•

http://ei.cornell.edu/biodeg/bioremed/

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http://www.pollutionissues.com/A-Bo/Bioremediation.html

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http://www.soilutions.co.uk/services/soil-remediation/bioremediation/

•

http://www.slideplayer.com/slide/1523117/#

•

http://krockne.people.uic.edu/proceeding9.pdf

•

https://clu-

in.org/download/remed/introductiontoinsitubioremediationofgroundwater_dec2013.

pdf

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http://home.engineering.iastate.edu/~tge/ce421-521/matt-r.pdf

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A Citizen’s Guide To Bioremediation