ch 9 lecture
TRANSCRIPT
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Chapter 9
Bioremediation
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9.1 What Is Bioremediation?
• Biodegradation - the use of living organisms suchas bacteria, fungi, and plants to degrade chemical
compounds
•
Bioremediation –
process of cleaning upenvironmental sites contaminated with chemical
pollutants by using living organisms to degrade
hazardous materials into less toxic substances
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9.1 What Is Bioremediation?
• 1980 Superfund Program established by U.S.Congress – Initiative of the U.S. Environmental Protection Agency
(EPA)
– To counteract careless and even negligent practices of chemical dumping and storage, as well as concern over how these pollutants might affect human health and theenvironment
– Purpose is to locate and clean up hazardous waste sites
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9.1 What Is Bioremediation?
• Environmental Genome Project – Purpose is to study and understand the impacts of
environmental chemicals on human disease
• Why use bioremediation?
– Most approaches convert harmful pollutants into
relatively harmless materials such as carbon dioxide,
chloride, water, and simple organic molecules
– Processes are generally cleaner
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9.1 What Is Bioremediation?
• Biotechnological approaches are essential for – Detecting pollutants
– Restoring ecosystems
– Learning about conditions that can result in human
diseases
– Converting waste products into valuable energy
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9.2 Bioremediation Basics
• What needs to be cleaned up? – Soil, water, air, and sediment
• Pollutants enter environment in many differentways – Tanker spill, truck accident, ruptured chemical tank at
industrial site, release of pollutants into air
• Location of accident, the amount of chemicalsreleased, and the duration of the spill impacts the
parts of the environment affected
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9.2 Bioremediation Basics
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9.2 Bioremediation Basics
• Chemicals in the Environment – Carcinogens
– Mutagens
– Cause skin rashes, birth defects
– Poison plant and animal life
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9.2 Bioremediation Basics
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9.2 Bioremediation Basics
• Fundamentals of Cleanup Reactions – Microbes convert chemicals into harmless substances by
either
• Aerobic metabolism (require oxygen) or anaerobic
metabolism (do not require oxygen)
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9.2 Bioremediation Basics
• Aerobic and Anaerobic Biodegradation
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9.2 Bioremediation Basics
• The Players: Metabolizing Microbes – Indigenous microbes – those found naturally at a polluted site
– Bacteria
• Pseudomonas
•
E.coli – Algae and fungi
• Phanerochaete chrysosporium
• Phanerochaete sordida
• Fusarium oxysporum
• Mortierella hyaline
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9.2 Bioremediation Basics
• Stimulating Bioremediation – Nutrient enrichment (fertilization) – fertilizers are added
to a contaminated environment to stimulate the growth of
indigenous microorganisms that can degrade pollutants
– Bioaugmentation (seeding) –bacteria are added to thecontaminated environment to assist indigenous microbes
with biodegradative processes
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9.3 Cleanup Sites and Strategies
• Soil Cleanup – Ex situ bioremediation
• Slurry phase bioremediation
• Solid phase bioremediation
– Composting
– Land farming
– Biopiles
– In situ bioremediation
• Bioventing – pumping either air or hydrogen peroxide into
the contaminated soil
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9.3 Cleanup Sites and Strategies
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9.3 Cleanup Sites and Strategies
• Bioremediation of Water – Wastewater treatment
– Groundwater cleanup
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9.3 Cleanup Sites and Strategies
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9.3 Cleanup Sites and Strategies
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9.3 Cleanup Sites and Strategies
• Turning Wastes into Energy – Methane gas used to produce electricity
– Soil nutrients can be sold commercially as fertilizers
– Anaerobes in sediment that use organic molecules to
generate energy
• Electicigens – electricity-generating microbes
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9.3 Cleanup Sites and Strategies
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9.4 Applying Genetically Engineered
Strains to Clean Up the Environment
• Petroleum-Eating Bacteria – Created in 1970s
– Isolated strains of pseudomonas from contaminated soils
– Contained plasmids that encoded genes for breaking
down the pollutants
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9.4 Applying Genetically Engineered
Strains to Clean Up the Environment
• E. coli to clean up heavy metals – Copper, lead, cadmium, chromium, and mercury
• Biosensors – bacteria capable of detecting a
variety of environmental pollutants• Genetically Modified Plants and Phytoremediation
– Plants that can remove RDX and TNT
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9.5 Environmental Disasters: Case Studies
in Bioremediation
• Jet Fuel and Hanahan, South Carolina• The Exxon Valdez Oil Spill
• Oil Fields of Kuwait
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C ©
9.6 Future Strategies and Challenges for
Bioremediation
• Recovering Valuable Metals• Bioremediation of Radioactive Wastes