Biorem Presentation

8/2/2019 Biorem Presentation

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Bioremediation


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Why bioremediation is required?

Waste generation:a) Domestic waste

b) Industrial waste

c) Agricultural waste

d) Food waste

Use of chemicals for various purposes:

a) Insecticides

b) Pesticides

c) Chemical fertilizers

d) Toxic pdts, by pdts from chemical industry.

What are Conventional clean up methods?

Incineration of wastes

Pumping water to the ground

Dumping wastes on to other sites

Environmental biotechnology?


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The Aim of the environmental biotechnology should be to develop such processes which will

minimize the damage to the environment.

What is Bioremediation?

Bioremediation is a treatment process that uses microorganisms (yeast, fungi, or bacteria) to break

down, or degrade, hazardous substances into less toxic or nontoxic substances.

Microorganisms, just like humans, eat and digest organic substances for nutrients and energy. In

chemical terms, "organic" compounds are those that contain carbon and hydrogen atoms. Certain

microorganisms can digest organic substances such as fuels or solvents that are hazardous to humans.

The microorganisms break down the organic contaminants into harmless products -- mainly carbon

dioxide and water.

Microorganisms ----- Degradation (Break down) ---Organic matterPlants ------- assimilation (being absorbed into or incorporated) ------------ heavy metals.

What are advantages of bioremediation?Its a natural process.

b) Residues of the treatment are usually harmless products like: Co2 and water.


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Almost complete destruction of contaminated material.

d) It can also be carried out in-situ without causing disruption of normal activities.

e) Its a less expensive compared to other clean-up technologies.

What are the disadvantages of Bioremediation?

a) It is limited to only those compounds that are biodegradable.

b) It is highly specific technique, so all factors should be proper.

c) It is difficult to extrapolate from, Bench------Pilot scale--------Full scale field operations.

d) It takes longer time than other treatment options.

e) There are no acceptable endpoints for bioremediation treatments.

Will bioremediation work at every site?

Bioremediation is helpful in the clean up of many organic waste, however it does have its limitations.


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The extent of remediation is highly dependent on the toxicity and the initial levels of contaminants, their

ability to be biodegraded and the properties of the soil in which the contaminants lie. The types of

contaminates that are generally targeted for bioremediation are non-halogenated volatile and semi-volatile organics and fuels. Sites that are unable to be cleaned with microbes include those with high

metal concentrations (i.e. mercury), highly chlorinated organics (compounds with many chlorine

elements attached), and inorganic salts. These types of compounds are toxic to the microbes.

There are, however, some forms of plant life that are capable of removing heavy metals form soils with

little to no effect on the plant, called Phyto-remediation.

If they already occur in nature, why are there still contaminated sites?

When a microbe population is present at a site and is capable of cleaning a site it's called Natural

attenuation. Natural attenuation is often slow and isn't always able to clean a site before the

contamination spreads.

What happens to the microbes when the cleanup is complete?

After a site is remediated, the microbial populations return to a level consistent with the amount of food

and water available by dying off or returning to a spore state.


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Factors Influencing Bioremediation:

1) pH: (H+ ion concentration)

Optimum: 7.0

in Soil pH the availability of ca, mg, Na, k ,NH3, N2 & P.

In soil pH the availability of Nitrate & chloride.

2) Temprature:

Optimum: 20 - 40C (mesophilic orgs)

In cold areas steam can be injected into the soil layers to increase the temperature.

Whereas in hot regions water can be sprinkled to bring down the temperature.

3) Water content:

Water in soils or sediments may not be available due to its absorption onto solid substances or

tied up as water of hydration to dissolved solutes.

This can be solved by irrigating the contaminated sites.

Optimum: Rates of degradation are enhanced when soil is porous with high permeability.


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Rocky conditions and water logged conditions are not favourable.

4) Nutrient availability:

Nutrients are required by both ex-situ and in-situ bioremediation processes.

5) External electron availability:

O2 is mainly used as the terminal electron acceptor. (For aerobic processes).

Anaerobic bacterias can also breakdown variety of aliphatic and aromatic organic compounds of

both natural and anthropogenic origin, either wholly or partially by denitrifying bacteria (nitrates ---

N2), sulphate, iron and molybedenum reducers.

Efforts are being made to utilize anaerobic bacteria for breaking down petroleum contaminants

using nitrates.

Compounds like benzene, toluene, ethyl benzene, xylene have been successfully removed.

Methanogenic bacterias can degrade: Chlorinated ethanes like: tetrachloroethane,

trichloroethane, dicholroethane, Chloroform, tetrachloromethane have been successfully

removed.


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6) Gene expression:

The ability of an organism to degrade the contaminants depends upon the expression of the genes

encoding the required enzymes. When low quantities of contaminant is present genes are not expressed.

Induction (Compounds similar to contaminants)

Repression (alternate carbon or energy source)

7) Co-metabolism: Co-metabolism is a process in which microorganisms involved in the metabolism of a growth

promoting substrate also transforms other organic contaminants(only source of carbon and energy) .

Eg: lactose = glucose + galactose

It is used for transformation of DDT (dichloro diphenyl tri chloroethane ),

PCBS(Polychlorinated biphenyls), TCE (trichloro ethane.)


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Does bioremediation have to take place at a site?

No, there are two general categories of bioremediation, in site and ex site. The previous mentioned methods are all in site. Ex site is the process of

removing contaminated soil or water and treating it elsewhere.


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In-situ techniques:

1. Natural attenuation:


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Natural attenuation defines the natural occurring processes in the subsurface environment such

as dilution, volatilization, biodegradation, adsorption and chemical reactions with subsurface

compounds that contain the spread of pollution and reduce the concentration and amount ofpollutants at polluted sites.

The processes contributing to natural attenuation are typically acting at many sites, but at varying

rates and degrees of effectiveness, depending on the types of pollutants present and

physical, chemical and biological characteristics of the soil and groundwater.

Natural attenuation may be an acceptable option for sites that have been through some activeremediation, which has reduced the concentration of pollutants.

The rate of natural attenuation processes is typically slow.

Long term monitoring is necessary to demonstrate that pollutant concentrations are continually

decreasing at a rate sufficient to ensure that they will not become a health treat.

Favorite pollutants for natural attenuation are non-halogenated volatile organic compoundsand fuel hydrocarbons.

2. Bioventing (aerobic biodegradation):


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Biostimulation involves the modification of the environment to stimulate existing bacteria

capable ofbioremediation.

This can be done by addition of various forms of limiting nutrients, such as phosphorus,nitrogen, orcarbon(e.g. in the form ofmolasses). Additives are usually added to the subsurface

through injection wells.

The primary advantage of biostimulation is that bioremediation will be undertaken by already

present native mocroorganisms that are well suited to the subsurface environment, and are well

distributed spatially within the subsurface. The primary disadvantage is that the delivery of additives in a manner that allows the additives to

be readily available to subsurface microorganisms is based on the local geology of the

subsurface. Tight, impearmeable subsurface lithology (tight clays or other fine-grained

material) make it difficult to spread additives throughout the affected area.

Fractures in the subsurface create preferential pathways in the subsurface which additiviespreferentially follow, preventing even distribution of additives.

Biostimulation requires absence ofheavy metals, organic compounds or inorganic salts.
http://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Nutrienthttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Molasseshttp://en.wikipedia.org/wiki/Clayhttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Nutrienthttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Molasseshttp://en.wikipedia.org/wiki/Clayhttp://en.wikipedia.org/wiki/Bacteria


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Water based nutrient solutions through the soil may increase the contaminants mobility and

necessiate treatment of underlying ground water. Due to this preferential microbial colonization

can take place and can cause clogging of nutrient and water injection wells.

4. Air sparging:

This technology stimulates aerobic biodegradation of ground water contamination by delivery

of oxygen to the subsurface.

This is accomplished by injecting airbelow the water table through injection wells. This technology is designed primarily to treat ground water contamination by fuels, non-

halogenated (VOCs), (SVOCs), pesticides, organics and herbicides.

It can be used to treat halogenated organics but it is less effective.

The technology is simple, inexpensive, with low maintenance cost and can be left

unattended for long periods of time. This technology requires the presence of indigenous organisms capable of degrading the

contaminants of interest as well the nutrients required for the growth and the contaminants

should be available to the organisms.

It requires absence ofheavy metals, organic compounds or inorganic salts.


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5. Bioaugmentation:

Bioaugmentation is simply the introduction of a group of natural microbial strain or a

genetically engineered variant so as to achieve bioremediation.

It involves studying the indigenous varieties present in the location to determine ifbiostimulation is

possible. If the indigenous variety do not have the metabolic capability to perform the remediation

process, exogenous varieties with such sophisticated pathways are introduced.

6. In situ chemical treatment:

In this method, chemical compounds are used to transform pollutants in the subsurface.

In situ chemical treatment processes generally consist ofinstalling a series of injection wells for

delivering chemical compounds at the head or within the plume of polluted groundwater.

Chemicals that are added can oxidize or reduce pollutants, converting them to nontoxic forms

or immobilizing them to minimize their migration ability. Possible oxidizing compounds include

hydrogen peroxide, ozone and potassium permanganate. The most often used reducing agent

includes sulfur dioxide, sulfide salts, ferrous sulfate, metallic iron and zinc.

Chemical treatment could enhance in situ bioremediation.
http://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Endemic_(ecology)http://en.wikipedia.org/wiki/Biostimulationhttp://en.wikipedia.org/wiki/Metabolichttp://en.wikipedia.org/wiki/Exogenoushttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Endemic_(ecology)http://en.wikipedia.org/wiki/Biostimulationhttp://en.wikipedia.org/wiki/Metabolichttp://en.wikipedia.org/wiki/Exogenous


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Ozonation of an organic compound usually creates compounds that are more polar than the

parent compound and thus often increase the solubility and improves its bioavailability.

An advantage of coupling chemical and biological reactions is a reduction in the amount ofoxidant required to destroy the pollutant compound.

Like other methods, chemical treatment is limited by geologic complexities that complicate the

delivery of chemicals to the polluted area.

The chemical reactions are often nonspecific and the oxidant is capable of reacting with

inorganic and organic reductants in the soil and as a result the chemical must be supplied inamounts that far exceed the amount necessary to eliminate the pollutant.


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Air sparging:

Bioventing:


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In-situ chemical treatment.


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Biostimulation Chemical treatment


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Nutrients addition H2O2 Injection

Biostimulation


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Biorem Presentation