This document provides an overview of bioremediation presented by Md. Shoyeb. It defines bioremediation as using organisms or their enzymes to return polluted environments to their original condition. The mechanisms, principles, strategies (in situ and ex situ), types (bioventing, biosparging, bioaugmentation), advantages and disadvantages are summarized. Key contaminants amenable to bioremediation are identified along with persistent pollutants that are difficult to degrade.

2. A PRESENTATION
ON
BIOREMEDIATN
COURSE TITLE: Advanced Agricultural & Environmental Biotechnology
COURSE NO: GEBT 5105
PRESENTED TO
Forhad Karim Saikot
Lecturer
Dept. of Genetic Engineering and Biotechnology
Jessore University of Science and Technology, Jessore
PRESENTED BY
Md. Shoyeb
Roll No: MS-130611
Session: 2013-14
Dept. of Genetic Engineering &
Biotechnology
Jessore University of Science and Technology , Jessore 7408, Bangladesh

3. BIOREMEDIATION
 Bioremediation is the beneficial form of biodegradation.
 In general bioremediation can be defined as the process by which
organisms transform chemicals.
 For our purposes it is the transformation of chemicals considered to be
contaminants or pollutants.
 Bioremediation is any natural, environmentally friendly process that uses
organisms (microorganism, algae and plant) or their enzymes (process
known as Cometabolism) to return the polluted environment to its original
condition.

4. MECHANISMS OF BIOREMEDIATION
 Contaminant compounds are transformed by living organisms through
reactions that take place as a part of their metabolic processes
 Organic compounds (contaminants) act as the source of carbon and
electrons
 Carbon act as the source of cell building material and electrons as the
source of energy
 Basic mechanism of bioremediation is that microbes catalyses the
oxidation of the organic compounds (contaminants) that cause transfer of
electrons from organic chemicals to some electron acceptor

5. ELECTRON ACCEPTORS
 In cases where the contaminant preferentially degrades faster aerobically,
enhancing bioremediation can be easily accomplished by adding an electron
acceptor
 There are a number of electron acceptors but oxygen is usually the most
efficient
 Other electron acceptors include nitrate, iron, and sulfate are used in
anaerobic condition
 Many chlorinated solvents degrade faster as electron acceptors. In these
cases, an electron donor is added to the system to begin the process. As the
substrate is metabolized under anaerobic conditions, an electron is released
and is then used to replace a chlorine atom on the chlorinated solvent
 The ability to cost-effectively provide sufficient electron acceptor adequately
distributed through the system is critical to successfully meeting the goals

6. PRINCIPLE OF BIOREMEDIATION
The principles of bioremediation are based on-
 Natural attenuation is the simplest method of bioremediation in which
soils are only monitored for variations in pollution concentrations to
ensure that the pollutant transformation is active
 Bioaugmentation is usually applied in cases where natural active microbial
communities are present in low quantities or even absent, wherein the
addition of contaminant degrading organisms can accelerate the
transformation rates
 Biostimulation:The capacity of a microbial population to degrade
pollutants can be enhanced also by stimulation of the indigenous
microorganisms by addition of nutrients or electron acceptors

7. RELATIVE BIODEGRADABILITY
The chemical structure of a compound affects biodegradability in following
ways-
 Degradability decreases as molecular weight increases
 Degree of branching decreases degradability
 Substitution makes a compound harder to degrade. For example, benzene
rings are easier to break down than benzene rings that have undergone
substitution

8. RELATIVE BIODEGRADABILITY
Pesticides
Chlorinated hydrocarbons
Nitrobenzenes and ethers
Alcohols, esters
Aromatic hydrocarbons
Simple hydrocarbons and petroleum fuels

9. BIOREMEDIABLE CONTAMINANTS
 There are a huge number of bioremediable contaminants in the
environment
 Many of the contaminants are degraded in aerobic condition with the
presence of oxygene
 Some are degraded in anaerobic condition in absence of oxygene

10. LIST OF BIOREMEDIABLE CONTAMINANTS

11. BIOREMEDIATION STRATEGIES
Different techniques are employed depending on the degree of saturation
and aeration of an area
There are two strategies for bioremediation:
 In situ bioremediation
 Ex situ bioremediation

12. IN SITU BIOREMEDIATION
 In situ bioremediation is the application of biological treatment to the
cleanup of hazardous chemicals present in the subsurface
 The treatment in place without excavation of contaminated soils or
sediments
 Applied to soil and groundwater at the site with minimal disturbance
 The most desirable options due to lower cost and less disturbance

13. TYPES OF IN SITU BIOREMEDIATION
There are four basic types in situ bioremediation
Bioventing
 It involves venting of oxygen to stimulate growth of natural or introduced microorganisms.
 Bioventing typically uses low air flow rates to provide only enough oxygen to sustain
microbial activity.
 Oxygen is most commonly supplied through direct air injection into residual contamination
 This technique shows considerable promise of stabilizing or removing inorganics from soil
In situ biodegradation
 It involves the infiltration of water-containing nutrients and oxygen or other electron
acceptors for groundwater treatment
 In situ biodegradation involves supplying oxygen and nutrients by circulating aqueous
solutions through contaminated soils

14. TYPES OF IN SITU BIOREMEDIATION
Biosparging
 In situ air sparging is a remediation technique that has been used since
about 1985
 Biosparging is used for the remediation of volatile organic compounds
(VOCs) dissolved in the groundwater
 Biosparging involves the injection of air under pressure below the water
able to increase groundwater oxygen concentrations
 The ease and low cost of in the design and construction of the system

15. TYPES OF IN SITU BIOHRMEDIATION
Bioaugmentation
 It Involves the addition of microorganisms indigenous or exogenous to the
contaminated sites
 Two factors limit the use of added microbial cultures in a land treatment
unit:
I. Non indigenous cultures rarely compete well enough with an indigenous
population to develop and sustain useful population levels
II. Most soils with long-term exposure to biodegradable waste have
indigenous microorganisms that are effective degrades if the land
treatment unit is well managed

16. EX SITU BIOREMEDIATION
 Ex situ refers to a technology or process for which contaminated material must
be removed from the site of contamination for treatment.
 Soil must be excavated or groundwater must be pumped to an above ground
treatment system in ex situ bioremediation.
Types of ex situ bioremediation
There are mainly four types of ex situ bioremediation
 Landfarming
 Composting
 Biopiles
 Bioreactors

17. LANDFARMING
 Landfarming, also known as land treatment
or land application, is an above-ground
remediation technology for soils
 Landfarming is a simple technique in which
contaminated soil is excavated and spread
over a prepared bed and periodically tilled
until pollutants are degraded.
 The effectiveness of landfarming depends
on parameters such as soil characteristics,
climatic conditions, Soil texture etc
Contaminated Soil Treatment

18. COMPOSTING
 Compost bioremediation refers to the use of a biological system of micro-
organisms in a mature, cured compost to sequester or break down
contaminants in water or soil.
 It involves 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

19. BIOPILES
 Biopile”, also known as biocell, bioheap, biomound or compost pile
 It means a pile of contaminated soils used to reduce concentrations of
petroleum constituents in excavated soils through the use of
biodegradation.
 This technology involves heaping contaminated soils into piles or “cells”
and stimulating aerobic microbial activity within the soils through the
aeration or addition of minerals, nutrients and moisture.
 It is a hybrid of landfarming and composting

20. BIOREACTORS
 Bioreactor is an apparatus, such as a large fermentation chamber, for
growing organisms such as bacteria or yeast under controlled conditions
 Bioreactors are used in the biotechnological production of substances
such as pharmaceuticals, antibodies, or vaccines, or for the bioconversion
of organic waste.
 Slurry reactors or aqueous reactors are used for ex situ treatment of
contaminated soil and water pumped up from a contaminated plume.

21. ADVANTAGES
 It is possible to completely breakdown organic contaminants into other
nontoxic chemicals
 Equipment requirements are minimal compared to other remediation
technologies.
 Bioremediation is perceived positively by the public because it is a natural
process.
 Does not transfer contaminants from one environment to another
 Can be implemented as an in-situ or ex-situ method depending on
conditions.
 Low-technology equipment is required i.e. readily available equipment
e.g. pumps, well drilling equipment etc.
 Low cost of treatment compared to other remediation technologies.

22. DISADVANTAGES
 Organic contaminants may not be broken down fully resulting in toxic by-
products that could be more mobile than the initial contamination
 The process is sensitive to the level of toxicity and environmental
conditions
 Field monitoring to is advised.
 If an ex-situ process is used, controlling volatile organic compounds (VOCs)
may be difficult.
 Treatment time is typically longer than that of other remediation
technologies.
 Range of contaminants that can be effectively treated is limited to
compounds that are biodegradable.
 Difficult to extrapolate from bench and pilot-scale studies to full-scale field
operations
 Performance evaluations are difficult because there is not a defined level
of a "clean" site and therefore performance criteria regulations are
uncertain.

23. PERSISTENT POLLUTANTS
 Persistent organic pollutants(POPs) are synthetic (man-made) organic
chemicals
 Low water solubility(they do not easily dissolve in water)
 The ability to accumulate in fat (high lipophilicity)
 Resistance to biodegradation (they take a very long time to break down and
stop being harmful).
 High levels in fish and marine mammals
 These chemicals come from pesticides, industrial chemicals, and are the
unwanted by-products of industrial processes or combustion.

24. PERSISTENT POLLUTANTS
Examples: Endrin, Heptachlor, Mirex, PCBs: Polychlorinated biphenyls, HCB:
Hexachlorobenzene etc
EFFECTS OF POPs
 Reproductive impairment and malformations
 Long-term effects on intellectual function
 Altered liver enzyme function
 Increased risk of tumours

25. THE XENOBIOTICS
 Xenobiotics is a compound that is foreign to the body ; a chemical which
is not normally produced or expected to be present in body.
 These compounds are man-made chemicals that are present in the
environment at unnaturally high concentrations.
 The xenobiotic compounds are not produced naturally
 It is artificially produced by chemical synthesis for agricultural or industrial
purpose
 Low molecular weight

26. REASONS OF BEING NON BIODEGRADABLE
The xenobiotic compounds may be recalcitrant due to one or more of the
following reasons:
 They are not recognised as substrate by the existing degradative enzymes
 Inability of the compounds to induce the synthesis of degrading enzymes
 They are highly stable, i.e., chemically and biologically inert due to the
presence of substitution groups like halogens
 They are highly toxic or give rise to toxic products due to microbial activity
 Their large molecular size prevents entry into microbial cells
 Lack of the permease needed for their transport into the microbial cells

27. BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC
DEGRADATION
 Certain microbes on continuous exposure to xenobiotics develop the
ability to degrade the same as a result of mutations.
 Mutations resulted in modification of gene of microbes so that the active
site of enzymes is modified to show increased affinity to xenobiotics.
 Use of mixed population of microbes is usually recommended
 The modification of certain genes of microbes to break down xenobiotics
is also recommended and is seen to produce high level of accuracy.

28. BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC
DEGRADATION
Organic pollutants are degraded by various types of microbial
degradations such as-
 Bacterial degradation
 Microfungi and mycorrhiza degradation
 Yeasts degradation
 Filamentous fungi degradation
 Algae and protozoa

29. BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC
DEGRADATION
Some microbes able to degrade Xenobiotics

30. SOME MICROBES ABLE TO DEGRADE XENOBIOTICS

31. GENETIC REGULATION
 Genes for the degradation of synthetic pollutants are often associated
with plasmids and transposons
 Catabolic plasmids are circular, accessory DNA elements present in the
cytoplasm of many soil bacteria
 They confer on their host the ability to degrade environmental pollutants
 The very first catabolic plasmid to be isolated was the CAM plasmid of
Pseudomonas putida
 The first plasmid that encodes the degradation of synthetic molecules was
pJP1

32. PLASMID BORNE BACTERIA CONTROL XENOBIOTICS;
MOSTLY FROM PSEUDOMONAS GENUS

33. Thanks to All