ch 9 lecture

7/29/2019 Ch 9 Lecture

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Chapter 9

Bioremediation

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

• 1980 Superfund Program established by U.S.Congress – Initiative of the U.S. Environmental Protection Agency

– 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

• 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

• Biotechnological approaches are essential for – Detecting pollutants

– Restoring ecosystems

– Learning about conditions that can result in human

diseases

– Converting waste products into valuable energy

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

• Chemicals in the Environment – Carcinogens

– Mutagens

– Cause skin rashes, birth defects

– Poison plant and animal life

• Fundamentals of Cleanup Reactions – Microbes convert chemicals into harmless substances by

either

• Aerobic metabolism (require oxygen) or anaerobic

metabolism (do not require oxygen)

• Aerobic and Anaerobic Biodegradation

• 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

• 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

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

• Bioremediation of Water – Wastewater treatment

– Groundwater cleanup

• 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

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

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

9.5 Environmental Disasters: Case Studies

in Bioremediation

• Jet Fuel and Hanahan, South Carolina• The Exxon Valdez Oil Spill

• Oil Fields of Kuwait

9.6 Future Strategies and Challenges for

Bioremediation

• Recovering Valuable Metals• Bioremediation of Radioactive Wastes

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