copyright © 2009 pearson education, inc. bioremediation

Copyright © 2009 Pearson Education, Inc.

Bioremediation


What Is Bioremediation?

• Biodegradation - the use of living organisms such as bacteria, fungi, and plants to degrade chemical compounds

• Bioremediation – process of cleaning up environmental 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

(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 the environment

– 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


Bioremediation Basics

• What needs to be cleaned up?– Soil, water, air, and sediment

• Pollutants enter environment in many different ways– Tanker spill, truck accident, ruptured chemical tank at

industrial site, release of pollutants into air

• Location of accident, the amount of chemicals released, 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 the contaminated environment to assist indigenous microbes with biodegradative processes


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


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


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


Environmental Disasters: Case Studies in Bioremediation

• Jet Fuel and Hanahan, South Carolina• The Exxon Valdez Oil Spill• Oil Fields of Kuwait• BP Oil Spill in Gulf of Mexico


Future Strategies and Challenges for Bioremediation

• Recovering Valuable Metals• Bioremediation of Radioactive Wastes

copyright © 2009 pearson education, inc. bioremediation

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