Bioremediation Bioremediation refers to the use of either naturally occurring or deliberately introduced microorganisms to consume and break down environmental pollutants, in order to clean a polluted site. The process of bioremediation enhances the rate of the natural microbial degradation of contaminants by supplementing the indigenous microorganisms (bacteria or fungi) with nutrients, carbon sources, or electron donors (biostimulation, biorestoration) or by adding an enriched culture of microorganisms that have specific characteristics that allow them to degrade the desired contaminant at a quicker rate (bioaugmentation). It is a cleaning process that degrades dangerous contaminants using naturally existing microbes. These bacteria may consume and degrade organic chemicals as a source of food and energy, degrade organic substances that are dangerous to living creatures, including humans, and degrade the organic pollutants into inert products. Because the bacteria already exist in nature, they offer no pollution concern Bioremediation is the use of microorganisms or microbial processes to detoxify and degrade environmental contaminants. Microorganisms have been used for the routine treatment and transformation of waste products for several decades Bioremediation strategies rely on having the correct microorganisms in the right location at the right time in the right environment for degradation to occur. The appropriate microorganisms are bacteria and fungi that have the physiological and metabolic competence to breakdown pollutants Objective of Bioremediation The objective of bioremediation is to decrease pollutant levels to undetectable, nontoxic, or acceptable levels, i.e., within regulatory limits, or, ideally, to totally mineralize organopollutants to carbon dioxide BIOREMEDIATION AND THEIR IMPORTANCE IN ENVIRONMENT PROTECTION Bioremediation is defined as ‘the process of using microorganisms to remove the environmental pollutants where microbes serve as scavengers’. • The removal of organic wastes by microbes leads to environmental clean-up. The other names/terms used for bioremediation are biotreatment, bioreclamation, and biorestoration. • The term “Xenobiotics” (xenos means foreign) refers to the unnatural, foreign and synthetic chemicals, such as pesticides, herbicides, refrigerants, solvents and other organic compounds. • The microbial degradation of xenobiotics also helps in reducing the environmental pollution. Pseudomonas which is a soil microorganism effectively degrades xenobiotics. • Different strains of Pseudomonas that are capable of detoxifying more than 100 organic compounds (e.g. phenols, biphenyls, organophosphates, naphthalene, etc.) have been identified. • Some other microbial strains are also known to have the capacity to degrade xenobiotics such as Mycobacterium, Alcaligenes, Norcardia, etc. Factors affecting biodegradation The factors that affect the biodegradation are: • the chemical nature of xenobiotics, • the conc

1. Bioremediation
Presentation on:
Ravindra Kumar Kachhap Oraon
Biotechnologist

2. Bioremediation
Bioremediation refers to the use of either naturally occurring or
deliberately introduced microorganisms to consume and break down
environmental pollutants, in order to clean a polluted site.
The process of bioremediation enhances the rate of the natural
microbial degradation of contaminants by supplementing the
indigenous microorganisms (bacteria or fungi) with nutrients, carbon
sources, or electron donors (biostimulation, biorestoration) or by
adding an enriched culture of microorganisms that have specific
characteristics that allow them to degrade the desired contaminant at
a quicker rate (bioaugmentation).
It is a cleaning process that degrades dangerous contaminants using
naturally existing microbes. These bacteria may consume and
degrade organic chemicals as a source of food and energy, degrade
organic substances that are dangerous to living creatures, including
humans, and degrade the organic pollutants into inert products.
Because the bacteria already exist in nature, they offer no pollution
concern.

3. Bioremediation is the use of
microorganisms or microbial processes
to detoxify and degrade environmental
contaminants.
Microorganisms have been used for the
routine treatment and transformation
of waste products for several decades
Bioremediation strategies rely on
having the correct microorganisms in
the right location at the right time in the
right environment for degradation to
occur. The appropriate microorganisms
are bacteria and fungi that have the
physiological and metabolic
competence to breakdown pollutants.

4. Objective of Bioremediation
The objective of bioremediation is to decrease pollutant levels to
undetectable, nontoxic, or acceptable levels, i.e., within regulatory
limits, or, ideally, to totally mineralize organopollutants to carbon
dioxide.

5. Bioremediation is defined as ‘the process of using microorganisms to remove
the environmental pollutants where microbes serve as scavengers’.
• The removal of organic wastes by microbes leads to environmental clean-up.
The other names/terms used for bioremediation are biotreatment,
bioreclamation, and biorestoration.
• The term “Xenobiotics” (xenos means foreign) refers to the unnatural, foreign
and synthetic chemicals, such as pesticides, herbicides, refrigerants, solvents
and other organic compounds.
• The microbial degradation of xenobiotics also helps in reducing the
environmental pollution. Pseudomonas which is a soil microorganism
effectively degrades xenobiotics.
• Different strains of Pseudomonas that are capable of detoxifying more than
100 organic compounds (e.g. phenols, biphenyls, organophosphates,
naphthalene, etc.) have been identified.
• Some other microbial strains are also known to have the capacity to degrade
xenobiotics such as Mycobacterium, Alcaligenes, Norcardia, etc.
BIOREMEDIATION AND THEIR IMPORTANCE IN ENVIRONMENT
PROTECTION

6. Factors affecting biodegradation
The factors that affect the
biodegradation are:
• the chemical nature of
xenobiotics,
• the concentration and supply of
nutrients,
• O2, temperature, pH, redox
potential and
• the capability of the individual
microorganism.

7. Bio-stimulation: It is a process by which the microbial activity can be
enhanced by increased supply of nutrients or by addition of certain
stimulating agents like electron acceptors, surfactants, etc.
Bio-augmentation: It is possible to increase biodegradation through
manipulation of genes i.e. using genetically engineered microorganisms and
by using a range of microorganisms in biodegradation reaction.
Depending on the method followed to clean up the environment,
bioremediation is carried out in two ways:
In situ bioremediation
Ex-situ bioremediation

8. In situ bioremediatio
In situ bioremediation is a direct technique for the microbial breakdown of
xenobiotics at the site of contamination, which might be soil, water, or both. The
location receives an adequate supply of vital nutrients, which stimulates
microbial development. In situ bioremediation is commonly employed to clean
up oil spills, beaches, and other areas. There are two forms of in situ
bioremediation:
1. Intrinsic bioremediation
2. Engineered in situ bioremediation

9. Intrinsic bioremediation
The microorganisms utilised for biodegradation are examined for their inherent capacity to cause biodegradation.
Hence, intrinsic bioremediation is the inherent metabolic capacity of microorganisms to digest certain contaminants.
The capacity of surface bacteria to digest a specific combination of pollutants in ground water is determined by the
kind and concentration of chemicals, the electron acceptor, and the length of time the bacteria are exposed to
contamination.
As a result, the capacity of indigenous bacteria to degrade pollutants may be assessed in the laboratory utilising plate
count and microcosm experiments.
The conditions of site that favour intrinsic bioremediation are groundwater flow throughout the year, carbonate
minerals to buffer acidity produced during biodegradation, supply of electron acceptors and nutrients for microbial
growth, and absence of toxic compounds.

10. Engineered in situ bioremediation
When the bioremediation process is engineered to increase the metabolic degradation
efficiency (of pollutants), it is called engineered in-situ bioremediation. This is done by
supplying sufficient amount of nutrients and oxygen supply, adding electron acceptors, and
maintaining optimal temperature and pH. This is done to overcome the slow and limited
bioremediation capability of microorganisms.

11. Advantages of in situ bioremediation
• The method ensures minimal exposure to public or site personnels.
• There is limited or minimal disruption to the site of bioremediation
• Due to these factors, it is cost effective.
• The simultaneous treatment of contaminated soil and water is possible.
Disadvantages of in situ bioremediation
• The sites are directly exposed to environmental factors like temperature, oxygen supply, etc.
• The seasonal variation of microbial activity exists.
• Problematic application of treatment additives like nutrients, surfactants, oxygen, etc.
• It is a very tedious and time-consuming process.

12. Ex-situ bioremediation
In this, the waste and the toxic material is collected from the polluted sites and the selected
range of microorganisms carry out the bioremediation at designated place. This process is an
improved method over the in situbioremediation method. On the basis of phases of
contaminated materials under treatment, ex-situ bioremediation is classified into two :
• Solid phase system and
• Slurry phase system.

13. a) Solid phase treatment
• This system includes land treatment and soil piles comprising of organic
wastes like leaves, animal manures, agricultural wastes, domestic and
industrial wastes, sewage sludge, and municipal solid wastes.
• The traditional clean-up practice involves the informal processing of
the organic materials and production of composts which may be used
as soil amendment.
• Composting is a self-heating, substrate-dense, managed microbial
system which is used to treat large amount of contaminated solid
material.
• Composting can be done in open system i.e. land treatment and/or in
closed treatment system.
• The hazardous compounds reported to disappear through composting
include aliphatic and aromatic hydrocarbons and certain halogenated
compounds.
• The possible routes leading to the disappearance of hazardous
compounds include volatilization, assimilation, adsorption,
polymerization and leaching

14. b) Slurry phase treatment
• This is a triphasic treatment system involving three major
components—
water, suspended particulate matter and air.
Here, water serves as suspending medium where nutrients, trace
elements, pH adjustment chemicals and desorbed contaminants
are dissolved.
• Suspended particulate matter includes a biologically inert
substratum consisting of contaminants and biomass attached to
soil matrix or free in suspending medium.
• The contaminated solid materials, microorganisms and water
formulated into slurry are brought within a bioreactor i.e.
fermenter.
• Biologically, there are three types of slurry-phase bioreactors:
aerated lagoons, low-shear airlift reactor, and fluidized-bed soil
reactor.
• The first two types are in use of full-scale bioremediation, while
the third one is in developmental stage.

15. Advantages of ex-situ bioremediation
• As the time required is short, it is a more efficient process.
• It can be controlled in a much better way.
• The process can be improved by enrichment with desired and more
efficient microorganisms.
Disadvantages of ex-situ bioremediation
• The sites of pollution remain highly disturbed.
• Once the process is complete, the degraded waste disposal becomes a
major problem.
• It is a costly process

16. (a) Aerobic bioremediation- When the biodegradation requires oxygen (O2) for the
oxidation of organic compounds, it is called aerobic bioremediation. Enzymes like
monooxygenases and dioxygenases are involved and act on aliphatic and aromatic
compounds.
(b) Anaerobic bioremediation: This does not require oxygen. The degradation process is
slow but more cost-effective since continuous supply of oxygen is not required.
(c) Sequential bioremediation: Some of the xenobiotic degradations require both aerobic
as well as anaerobic processes which very effectively reduce the toxicity e.g.,
tetrachloromethane and tetrachloroethane undergo sequential degradation.
Several types of reactions occur during the
bioremediation/microbial degradation

18. Phytoremediation:
Bioremediation by using plants is called
phytoremediation. Certain plant species which have the
capability to stimulate biodegradation of pollutants
(especially near the soil adjacent to roots- rhizosphere)
are cultivated near the sites of polluted soil. This is a
cheap and environmentally friendly process but takes a
long time to finish the clean-up process.
Methods of Bioremediation
Some examples of bioremediation-related technologies are:

19. Bioventing:
Bioventing involves aerobic biodegradation of pollutants by circulating air through
sub-surfaces of soil and is one of the very cost-effective and efficient technique
used for the bioremediation of petroleum-contaminated soils. It is very effectively
used for degradation of soluble paraffins and polyaromatic hydrocarbons.

20. Bioleaching:
Bioleaching is an effective technology for metal extraction from low-grade ores and
mineral concentrate. This is a simple process which can be done using
microorganisms such as Mesophiles, moderately thermophilic bacteria,
Extremophiles. Bioleaching is a part of Bioremediation.

21. Land-farming:
Land farming is a technique for the bioremediation of hydrocarbon contaminated
soils. In this, the soil is excavated, mixed with microorganisms and nutrients and
spread out on a liner just below the polluted soil.

22. Bioreactor:
The term "bioreactor" in the context of soil and water bioremediation refers to any
vessel or container where biological degradation of contaminants is isolated and
controlled.

23. Composting:
Piles of contaminated soils are constructed and treated
with aerobic thermophilic microorganisms to degrade
contaminants. Periodic physical mixing and moistening
of piles is done to promote microbial activity.

24. Bioaugmentation:
Addition of specific microorganisms to the
polluted soil constitutes bioaugmentation.
Some of the pollutants like
polychlorobiphenyls (PCBs), trinitrotoluene
(TNT), polyaromatic hydrocarbons (PAHs),
etc. are not degraded by only native soil
microorganisms so a combination of
microorganisms; referred to as
“consortium” or “cocktail” of
microorganisms; is added to achieve
bioaugmentation

25. Rhizo-filtration:
Rhizo-filtration is a form of phytoremediation that involves filtering contaminated
groundwater, surface water, and wastewater through a mass of roots to remove
toxic substances or excess nutrients.

26. Biostimulation:
Biostimulation involves stimulation of microorganisms already present in the
soil. This can be done by adding nutrients e.g. nitrogen, phosphorus etc., by
supplying co-substrates e.g. methane which can degrade trichloroethylene, or
by adding surfactants to disperse the hydrophobic compounds in water.

27. Source: In situ and Ex situ bioremediation techniques. | Download Table (researchgate.net)
In situ and Ex situ bioremediation techniques.

28. Advantages Disadvantages
A natural process.
Useful for the complete destruction of a wide
variety of contaminants.
Can be carried out on site, without disrupting
normal activities.
Eliminates the need to transport the waste off
site.
Eliminate the potential threats to human
health.
Less expensive.
Limited to only biodegradable compounds.
Products of biodegradation may be more toxic
than the parent compound.
Biological processes are often highly specific.
Require Sustainable environmental growth
conditions, and appropriate levels of nutrients
and contaminants.
Difficult to extrapolate from bench and pilot
scale studies to full scale field operation.
Takes longer time than other treatment options.
ADVANTAGES AND DISADVANTAGES OF
BIOREMEDIATION

29. Reference
Environmental Biotechnology Basic Concepts and Applications
- Viswanath Buddolla

31. THANK YOU