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Bioremediation of
Contaminated
Soils
Fariha Ilyas
Introduction
• Strategy or process that uses microorganisms, plants, or microbial or plant
enzyme to detoxify contaminants in the soil and other environments is called
Bioremediation.
• Any substance in the soil that exceeds naturally-occurring levels and poses
human & soil health risks is a soil contaminant. (Soil Science Society of America)
• Contaminants include:
 Chlorinated Solvents (TEC and PCE)
Trinitrotoluene (TNT)
 Heavy metals such as chromium and lead
 Pesticides
 Aromatic hydrocarbons (benzene , toluene etc.)
 Polyaromatic hydrocarbons (creosote mixture)
2 9/9/2018 Bioremediation of Contaminated Soils
Sources of Contaminants
• Industrial Activity
• Agricultural Activities
• Waste Disposal
• Accidental Oil Spillage
• Acid Rain
3 9/9/2018 Bioremediation of Contaminated Soils
Bioremediation Processes
4 9/9/2018 Bioremediation of Contaminated Soils
Biodegradation: Partial and sometimes
total, transformation or detoxification of
contaminants by microbes and plants
Mineralization: Complete conversion of
an organic contaminant to its inorganic
constituent by a single or multiple
species.
Cometabolism: Transformation of a
contaminant without providing it Carbon
or energy for degrading microbes.
Criteria for Bioremediation
• Organisms must have necessary catabolic activity to degrade contaminants
at a reasonable rate.
• The target contaminant must be bioavailable (e.g. not sorbed as a bound
residue).
• The site must have soil condition conducive to organism growth or activity.
• Not much expensive.
• Magnitude, toxicity and area of contamination
 Failure to meet any one of these criteria cause rejection of bioremediation
approach.
 Many compounds can not be degraded at a reasonable rate, such are referred
as Recalcitrant compounds e.g. Humus
5 9/9/2018 Bioremediation of Contaminated Soils
Biological Mechanisms ofTransformation
6 9/9/2018 Bioremediation of Contaminated Soils
Conversion
Conversion of
contaminants to
mineralized end
product
CO2, H2O & Salts
Biotransformation
Biotransformation,
where end product is
not mineral
TEC to DEC
Biodegradation
Involves the process
of extracting energy
from organic
chemicals via
oxidation of organic
chemicals
7 9/9/2018 Bioremediation of Contaminated Soils
Strategies for Bioremediation
• Intrinsic Bioremediation
• Biostimulation
• Bioventing
• Bioaugmentation
• Landfarming
• Composting
• Phytoremediation
8 9/9/2018 Bioremediation of Contaminated Soils
Intrinsic Bioremediation
9 9/9/2018 Bioremediation of Contaminated Soils
• Intrinsic bioremediation use indigenous microorganism to degrade
contaminant.
• No human intervention involved in this.
• Cheapest means of bioremediation.
• Most commonly used method.
• Too slow degradation.
Biostimulation
• Microbes are motivated to start the process of bioremediation
• Addition of nutrients to stimulate indigenous bacteria.
Bioventing
• Gaseous stimulants such as Oxygen & Methane are added passively
• It stimulate indigenous microbes activity
10 9/9/2018 Bioremediation of Contaminated Soils
Bioaugmentation
• Inoculation of microorganisms to facilitate bioremediation.
• Organisms are selected for their high degrading potential.
• Wild-type or genetically modified species.
 A single species
 Consortium of several species
11 9/9/2018 Bioremediation of Contaminated Soils
Landfarming
12 9/9/2018 Bioremediation of Contaminated Soils
• Incorporation of wastes into the
surface of non-contaminated soil.
• There is a thick clay layer to prevent
leachate from contaminating ground
water.
• Soil is plowed or disking
• Uniform distribution of fertilizer &
microbial inoculant
Composting
• Microorganisms are used in constructed
piles of soils or windrows to degrade
contaminants.
• Piles are physically mixed and moistened
to promote microbial activity.
13 9/9/2018 Bioremediation of Contaminated Soils
Phytoremediation
• Use of plants to remove or transform contaminants
• Affects directly or indirectly
14 9/9/2018 Bioremediation of Contaminated Soils
Hyper
accumulating
heavy metals
Stimulating
microbes in
rhizosphere
Case Study
Bioremediation of Soil
Biostimulation Example
• In U.S.,Alaska there was release of over 40million liters crude oil. Over
1500km of shoreline in the sound and Gulf of Alaska were contaminated to
varying degrees.
• Oil is rich with carbon and low in N & P
• A stable water in oil emulsion having N/P with 7.3/0.8 ratios was applied in
form of Inipol
• A thin layer of inipol was applied at shore at 300ml/sq. m
• Crude oil destabilize Inipol to release its N
• Increase the activity of indigenous hydrocarbon degrading bacteria.
• Enhance degradation of petroleum
• Passive bioremediation also occurred
16 9/9/2018 Bioremediation of Contaminated Soils
Inipol
Water in oil
formulation
Honey like
appearance
17 9/9/2018 Bioremediation of Contaminated Soils
Significance
of
Bioremediati
on
Less hazardous
No waste
generated
Natural
Process
Less expensive
Not suitable for
more than one
contaminant soil
Can be carried
out on Site
Takes few
months to years
Release of
contaminants in
environment
Climate issue
Advantages
Disadvantages

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Bioremediation of contaminated soils

  • 2. Introduction • Strategy or process that uses microorganisms, plants, or microbial or plant enzyme to detoxify contaminants in the soil and other environments is called Bioremediation. • Any substance in the soil that exceeds naturally-occurring levels and poses human & soil health risks is a soil contaminant. (Soil Science Society of America) • Contaminants include:  Chlorinated Solvents (TEC and PCE) Trinitrotoluene (TNT)  Heavy metals such as chromium and lead  Pesticides  Aromatic hydrocarbons (benzene , toluene etc.)  Polyaromatic hydrocarbons (creosote mixture) 2 9/9/2018 Bioremediation of Contaminated Soils
  • 3. Sources of Contaminants • Industrial Activity • Agricultural Activities • Waste Disposal • Accidental Oil Spillage • Acid Rain 3 9/9/2018 Bioremediation of Contaminated Soils
  • 4. Bioremediation Processes 4 9/9/2018 Bioremediation of Contaminated Soils Biodegradation: Partial and sometimes total, transformation or detoxification of contaminants by microbes and plants Mineralization: Complete conversion of an organic contaminant to its inorganic constituent by a single or multiple species. Cometabolism: Transformation of a contaminant without providing it Carbon or energy for degrading microbes.
  • 5. Criteria for Bioremediation • Organisms must have necessary catabolic activity to degrade contaminants at a reasonable rate. • The target contaminant must be bioavailable (e.g. not sorbed as a bound residue). • The site must have soil condition conducive to organism growth or activity. • Not much expensive. • Magnitude, toxicity and area of contamination  Failure to meet any one of these criteria cause rejection of bioremediation approach.  Many compounds can not be degraded at a reasonable rate, such are referred as Recalcitrant compounds e.g. Humus 5 9/9/2018 Bioremediation of Contaminated Soils
  • 6. Biological Mechanisms ofTransformation 6 9/9/2018 Bioremediation of Contaminated Soils Conversion Conversion of contaminants to mineralized end product CO2, H2O & Salts Biotransformation Biotransformation, where end product is not mineral TEC to DEC Biodegradation Involves the process of extracting energy from organic chemicals via oxidation of organic chemicals
  • 7. 7 9/9/2018 Bioremediation of Contaminated Soils
  • 8. Strategies for Bioremediation • Intrinsic Bioremediation • Biostimulation • Bioventing • Bioaugmentation • Landfarming • Composting • Phytoremediation 8 9/9/2018 Bioremediation of Contaminated Soils
  • 9. Intrinsic Bioremediation 9 9/9/2018 Bioremediation of Contaminated Soils • Intrinsic bioremediation use indigenous microorganism to degrade contaminant. • No human intervention involved in this. • Cheapest means of bioremediation. • Most commonly used method. • Too slow degradation.
  • 10. Biostimulation • Microbes are motivated to start the process of bioremediation • Addition of nutrients to stimulate indigenous bacteria. Bioventing • Gaseous stimulants such as Oxygen & Methane are added passively • It stimulate indigenous microbes activity 10 9/9/2018 Bioremediation of Contaminated Soils
  • 11. Bioaugmentation • Inoculation of microorganisms to facilitate bioremediation. • Organisms are selected for their high degrading potential. • Wild-type or genetically modified species.  A single species  Consortium of several species 11 9/9/2018 Bioremediation of Contaminated Soils
  • 12. Landfarming 12 9/9/2018 Bioremediation of Contaminated Soils • Incorporation of wastes into the surface of non-contaminated soil. • There is a thick clay layer to prevent leachate from contaminating ground water. • Soil is plowed or disking • Uniform distribution of fertilizer & microbial inoculant
  • 13. Composting • Microorganisms are used in constructed piles of soils or windrows to degrade contaminants. • Piles are physically mixed and moistened to promote microbial activity. 13 9/9/2018 Bioremediation of Contaminated Soils
  • 14. Phytoremediation • Use of plants to remove or transform contaminants • Affects directly or indirectly 14 9/9/2018 Bioremediation of Contaminated Soils Hyper accumulating heavy metals Stimulating microbes in rhizosphere
  • 16. Biostimulation Example • In U.S.,Alaska there was release of over 40million liters crude oil. Over 1500km of shoreline in the sound and Gulf of Alaska were contaminated to varying degrees. • Oil is rich with carbon and low in N & P • A stable water in oil emulsion having N/P with 7.3/0.8 ratios was applied in form of Inipol • A thin layer of inipol was applied at shore at 300ml/sq. m • Crude oil destabilize Inipol to release its N • Increase the activity of indigenous hydrocarbon degrading bacteria. • Enhance degradation of petroleum • Passive bioremediation also occurred 16 9/9/2018 Bioremediation of Contaminated Soils Inipol Water in oil formulation Honey like appearance
  • 17. 17 9/9/2018 Bioremediation of Contaminated Soils Significance of Bioremediati on Less hazardous No waste generated Natural Process Less expensive Not suitable for more than one contaminant soil Can be carried out on Site Takes few months to years Release of contaminants in environment Climate issue Advantages Disadvantages