1. BIOTECHNOLOGY AND ENVIRONMENT

2. Chapter Contents What Is Bioremediation? Bioremediation Basics
Cleanup Sites and Strategies
Applying Genetically Engineered Strains to Clean Up the Environment
Environmental Disasters: Case Studies in Bioremediation
Future Strategies and Challenges for Bioremediation

3. 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

4. Why is bioremediation important??
The quality of life directly related to the cleanliness and health of environment.
Environmental chemicals can influence our genetics: some chemicals can act as mutagens- leading to disease conditions- reason to concern on the consequences of environmental chemicals on human and animals.
Bioremediation is Way to clean up the environment thru cheaper and cleaner approach.
To convert harmful pollutants into relatively harmless materials such as carbon dioxide, chloride, water, and simple organic molecules
Bioremediation can be conducted at the site of contamination- complete clean up is possible.

5. 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

6. 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

7. Eg: leaking of chemical tanker
Eg: leaking of chemical tanker. Initially, only contaminate surface and subsurface soils; however, if large amounts of chemicals released and undetected, chemicals may move deeper into the soils.
Following heavy rains, these chemicals may create runoff that can contaminate the adjacent surface water supplies; ponds, river
Chemicals may leak into the ground creating leachate.
Leachate can cause contamination of subsurface water- common source of drinking water.

8. Bioremediation Basics
Chemicals in the Environment
Carcinogens
– Compounds that cause cancer
Mutagens
Cause skin rashes, birth defects
Poison plant and animal life

9. Bioremediation Basics

10. 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)
Both processes involve oxidation and reduction reactions
Oxidation – removal of one or more electrons from an atom or molecule
Reduction –addition of one or more electrons to an atom or molecule
During redox reaction, oxidizing agents (electron acceptor) accept electrons and become reduced.

11. Bioremediation Basics

12. Aerobic biodegradation
In environments such as surface water and soil, O2 is readily available
Aerobic bacteria degrade pollutants by oxidizing chemical compounds.
O2 can oxidized variety of chemicals including organic molecules such as petroleum products.
In the process, O2 is oxidized into water.
Microbes can further degrade the compounds into simpler molecules; CO2 and methane.
Bacteria derived energy from the process, producing more bacterial cells.

13. Anaerobic degradation
In some environments where O2 is lacking, biodegradation may take place thru anaerobic biodegradation.
Also requires redox reaction but using other molecules as electron acceptors.
Fe3+ , SO42+ , NO3- are common electron acceptors.

14. Metabolizing microbes
Ability of microbes to degrade different chemicals effectively depends on many conditions
Types of chemical, temp, zone of contamination, nutrients influence the effectiveness and rates of biodegradation/
The search for useful microbes for bioremediation is often carried out at the site of contamination.
Anything living in a polluted sites will have developed the resistance to the polluting chemicals.
Indigenous microbes- found naturally in the contaminated area.

15. The most common and effective microbes for bioremediation
Indigenous microbes
The most common and effective microbes for bioremediation
Indigenous microbes found naturally in the contaminated site
Isolated, grown and studied in the lab
Released back into the cleanup environments in large scale

16. Bioremediation Basics
Stimulating Bioremediation
Many indigenous microbes are very effective in biodegradation
There are a few strategies used to enhance the effectiveness of the microbes.
Nutrient enrichment (fertilization) – fertilizers are added to a contaminated environment to stimulate the growth of indigenous microorganisms that can degrade pollutants.
- Adding more nutrients, more microbes and grow rapidly, therefore, increases the rate of reaction.
Bioaugmentation (seeding) –bacteria are added to the contaminated environment to assist indigenous microbes with biodegradative processes

17. Phytoremediation: using plants to clean up the contaminated soils.
Chemical pollutants are taken up by roots of the plants as they absorb water from the contaminated soil.
The contaminated plants are disposed off or burned.
It can be low-cost, effective and low-maintainance approach.
Disadvantages: only surface layers can be cleaned up and may take several years to clean up.

18. Cleanup sites and strategies
Soil cleanup
Ex situ bioremediation (removing of contaminated soil to other locations for treatments)
In situ bioremediation (cleaning up at the contamination site without removal of soil to other location)

19. In situ bioremediation
Preferred method; Less expensive- soil and water does not have to excavated or pump out of the site and larger area can be treated.
Rely on stimulating microbes in the contaminated soil or water
Those that require aerobic degradation: involve bioventing
Bioventing: pumping air/H2O2 into the contaminated soil. H2O2 is used because it can be degraded into water and O2 easily to provide microbes with source of o2. Fertilizers may also be added to stimulate the growth of bacteria and degrading activities

20. Disadvantages of in situ bioremediation: not suitable for solid clay and dense rocky soils.
Soils that have been contaminated with chemicals persist for long periods of time can take years to clean up this way

21. Ex situ bioremediation
Slurry-phase bioremediation
Moving contaminated soil to another site, mixing with fertilizer and water in bioreactors in which conditions can be controlled and monitored.
Solid phase bioremediation (Composting, landfarming and biopiles)
More time consuming and requires a large amount of space.

22. Solid phase bioremediation
composting
Degrade household wastes, degrade chemical pollutant in contaminated soils.
Hay, strawa added to soil to provide bacteria with nutrients that help bacteria to degrade chemicals.
landfarming
Spreading contaminated soils on a pad so that water and leachates can leak out of the soil.
Primary goal: to collect leachate so that polluted water cannot further contaminate the environment
biopiles
When chemical in the soil can evaporate easily and when microbes in the soil pile degrade the pollutant rapidly
A few bulking agents are added and fans and piping systems are used to pump air into or over the pile.
As chemicals in the pile evaporate, the vacuum airflow pull the chemical vapors away from pile and released into the air/filter.

23. 9.3 Cleanup Sites and Strategies

24. Cleanup Sites and Strategies
Bioremediation of water
Wastewater treatment
Groundwater cleanup

25. Wastewater treatment It is a well known application of bioremediation
The purpose is to remove;
Human sewage
fecal material
paper wastes
Soaps
Detergents
Other household chemicals

26. Wastewater treatment: in typical septic system
Human sewage and wastewater from a household move thru plumbing system out to septic tank
Feces and paper wastes are ground and filtered into small particle. Settle out into a tanks to create mud like material- sludge
Water flow out of the tank called effluent and sent to aerating tanks- aerobic bacteria oxidize organic materials in the effluent
Effluent is passed into activated sludge system –tank containing microbes. Effluent then disinfected with chlorine and released to lake/river
Sludge is pumped into anaerobic digester tanks. Anaerobe microbes degrade the sludge producing methane gas.
Resulting sludge can be used as fertilizers

27. Cleanup Sites and Strategies

28. Groundwater cleanup
Groundwater- source of drinking water may be contaminated with pollutants.
Polluted groundwater can be difficult to clean up because it get trapped in soil and rocks.
Ex situ and in situ approaches are used in combination.
For eg: groundwater contaminated by gasoline/oil
These pollutants rise onto the surface of the aquifer,
It can be directly pumped out but the portion mixed with groundwater must be pumped to the surface and passed thru bioreactors
Inside bioreactor: bacteria in biofilms growing over a screen degrade the pollutants
The clean water containing fertilizer, bacteria pumped back into the aquifer for in-situ hybridization.

29. Cleanup Sites and Strategies

30. Cleanup Sites and Strategies
Turning Wastes into Energy
Wastes from landfills are used to produce energy
Scientists are working to produce bioreactors that contain anaerobic bacteria that can convert food wastes into soil nutrients and methane gas.
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

31. Applying Genetically Engineered Strains to Clean Up the Environment
Many indigenous microbes cannot degrade certain types chemicals: highly toxic compounds.
Radioactive compounds- kill microbes thus preventing biodegradation.
The development of genetic engineering- enable scientists to create genetically engineered microbes that capable of improving bioremediation process.

32. Petroleum eating bacteria
Created in 1970s
Isolated strains of pseudomonas from contaminated soils
Contained plasmids that encoded genes for breaking down the pollutants

33. 9.4 Applying Genetically Engineered Strains to Clean Up the Environment
E. coli to clean up heavy metals
Copper, lead, cadmium, chromium, and mercury
Genetically modified strain of E. coli that can degrade heavy metals.
Biosensors – bacteria capable of detecting a variety of environmental pollutants
Genetically Modified Plants and Phytoremediation
Plants that can remove RDX and TNT

34. Environmental Disasters: Case Studies in Bioremediation
jet fuel and Hanahan, south carolina
80,000 gallons kerosene leaked. After series of clean up- spill could not contained from soaking thru the sandy soil and contaminating the water
after 10 years, reached residential areas- removing contaminated soil was impractical- large area
Scientists found that indigenous microbes were degrading the fuel and adding fertilizers increasing the rate of biodegradation

35. Future Strategies and Challenges for Bioremediation
Recovering Valuable Metals
Metals such as copper, nickel, boron and gold.
Many microbes can convert metal products into insoluble substances called metal oxides that will accumulate in their cells/cell surface.
For eg: many manufacturing processes using silver and gold plating techniques that create waste solutions with suspended gold/silver particles. Microbes can be used to recover this metals.

36. Future Strategies and Challenges for Bioremediation
Bioremediation of radioactive wastes
Removing radioactive wastes from environment.
Although radioactive kill materials kill a majority of microbes, some strains of bacteria have demonstrated a potential for degrading radioactive chemicals.
For eg: Geobacter can reduce soluble uranium in groundwater into insoluble uranium effectively, immobilizing the radioactivity.