Biological Methods 10.1-Basic Microbial Metabolism 10.2 Biodegradation of Xenobiotics

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Biological Methods10.1-Basic Microbial
Metabolism10.2 Biodegradation of Xenobiotics
Materials are taken from the Textbook Hazardous
Waste Management. 2nd Ed. Legrega et al., McGraw
Hill
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Terminology

• Microorganisms
• By cell structure
• Procaryote
• Eucaryote
• By cell function
• Autotrophic
• Heterotrophic
• Cellular Metabolism
• Anabolism
• Catabolism

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Common Microorganisms

• Bacteria
• Fungi
• Algae
• Protozoa

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Heterotrophic Photoheterotrophic Light
Organic
carbon Chemoheterotrophic Oxidation-reduction
reactions of Organic carbon
organic compounds
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Factors Affecting Biodegradability

• Energy and substrate sources
• Enzymatic processes
• Substrate biodegradability
• Inhibition and toxicity
• Microbial community

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Biodegradability

• Straight chair aliphatic easily degraded
  branching strictly hindered configuration
  resistant to degradation unsaturated aliphatic
  less readily transformed than saturated
  analogues.
• Simple aromatics degradable by several
  mechanisms of ring cleaving substituted by
  halogens decreases degradability even highly
  chlorinated aromatics, PCBs can be degraded even
  slowly
• Nitrogen and sulfur compounds are linked to their
  uses as nutrients branched are difficult.
• Polymeric materials are the most difficult.

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Anaerobic Processes
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Engineering Factors
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Oxygen Requirements
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• Oxygen requirement for anabolic metabolism of
  alkene to cellular material
• Under anaerobic condition, the oxygen demand is
  supplied from water , not oxygen.
• C7H12 14H2O ? 7CO2 40 e 40 OH-
• 5O2 20 H 20e ? 10 H2O
• 5CO2 NH3 20 H 20 e ? C5H7O2N 8 H2O
• C7H12 NH3 5O2 ? C5H7O2N 2CO2 4H2O

• Summary of chemical equation for the anabolic
  alkene conversion to biomass
• C7H12 NH3 5O2 ? C5H7O2N 2CO2 4H2O

The new cellular material if mineralized during
endogenous respiration also exerts oxygen
demand C5H7O2N 5O2 ? 2H2O NH3 5CO2 Overall
C7H12 10O2 ? 7CO2 6H2O
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Bioreactors

• Suspended
• Activated sludge
• Attached
• Trickling filter BMR