L10

• Enormous quantities of organic & inorganic compounds are released into the environment each year as a result of human activities
• Release of compounds may be

  • Deliberate and well regulated (industrial emissions)
  • Accidental and largely unavoidable (chemical/oil spills)
• Industrial emissions


  • Chemical/oil spills
• Heavy metals (Pb, Hg, Cd, Ni and Be)


  • Can accumulate in various organs, interfere with normal enzymatic reactions and cause disease including cancer
• Chlorinated hydrocarbons (organochlorides)


  • Include pesticides and other organic compounds such as PCB (polychlorinated biphenyls)
  • Research proven a positive correlation between cancer in lab animals and organochlorides
• Nuclear waste


  • Includes radioactive material such as uranium and plutonium which are dangerous for thousands of years
• Characteristics of chemicals introduced into the environment

  • Volatile
  • Not volatile
  • Water soluble
  • Water insoluble
  • Chemically inert
  • Chemically reactive
• Fate of chemicals introduced into the environment

  1. Site accumulation/buildup

  2. Evaporation possible

  3. Accumulation in atmosphere

  4. Loss/disappearance

  5. Conditions favourable for reaction

  6. Water available

  7. Accumulation on site

  8. Transport in sediment & water (surface, ground)

  9. Amenable to degradation

  10. Not degradable

  11. Sorbed

  12. Not sorbed
• Contaminant removal mechanisms


  • Physical (Sedimentation, Precipitation, Filtration)
  • Chemical (Adsorption, Hydrolysis Rxn, Oxidation Rxn)
  • Biological (Bacterial metabolism, Plant metabolism, Volatilization, Natural die-off)
• Types of pollutants


  • Bio-degradable (petroleum products, crude oil compounds, some pesticides, some industrial solvents, coal compounds)
  • Partially degradable/Persistent (TCE, PCE, PCB's, Arsenic, Chromium, Selenium)
  • Not degradable/Recalcitrant (Uranium, Mercury, DDT)
• Remediate


  • To solve a problem
  • To right a wrong
• Bio


  Living organisms
• Bio-Remediate


  To use biological organisms to solve an environmental problem
• Steps in the degradation of organic wastes

  • Minor change in a molecule
  • Fragmentation
  • Mineralization
• Factors affecting bioremediation


  • Energy source
  • Electron acceptor
  • Moisture
  • pH
  • Nutrients
  • Temperature
  • Absence of toxicity
  • Removal of metabolites
  • Absence of competitive organisms
• Procaryotic and eucaryotic cells

  • The most important groups to bioremediation are bacteria and fungi
• Types of cells


  • Procaryotic
  • Eucaryotic
• Organisms


  • Bacteria
  • Blue-green bacteria or cyanobacteria
  • Plants
  • Animals
  • Rotifers
  • Protozoa
  • Fungi
  • Most algae
• Aerobic


  Where oxygen in some form is added to the treatment environment
• Anaerobic


  Where nitrate, iron, or other electron acceptor is added to the treatment environment
• Aerobic conditions


  • Molecular oxygen provides the electron acceptor for the oxidation of organic compounds
  • Organic carbon is used for energy and growth and this includes methane but not carbon dioxide
• Anaerobic conditions


  • Anaerobic bacteria live and grow in the presence of reduced compounds and with either the total absence of molecular oxygen or its greatly reduced concentration
  • Compounds which can serve as terminal electron acceptors for anaerobes are: carbon dioxide, nitrate, sulfate, iron, humates and glucose (producing lactic acid and ethanol)
• Cometabolism


  The transformation of a non-growth compound when an organism is growing on another substrate and deriving its carbon and energy from the second substrate. The first compound is "accidentally" transformed and provides no benefit to the organism.
• Types of compounds that can be treated biologically

  • Petroleum Hydrocarbons (Gasoline, Diesel Fuel, Gasoline Additives such as MTBE)
  • Polyaromatic Hydrocarbons (Creosote)
  • Chlorinated Hydrocarbons (Chlorinated Aliphatics: trichlorethylene, Chlorinated Aromatics: PCB's, Pentachlorophenol)
  • Explosives (RDX, TNT)
  • Inorganics via Reduction to a Lower Valence Causing Precipitation (Uranium, Technicium, Sulfur and Sulfuric Acid, Ammonia or Nitrate/Nitrite)
• Microorganisms destroy organic contaminants in the course of using the chemicals for their own growth and reproduction
• For degradation it is necessary that bacteria and the contaminants be in contact
• The availability of contaminants is necessary for degradation
• Types of in situ bioremediation

  • Intrinsic bioremediation
  • Accelerated bioremediation
• Intrinsic bioremediation


  Uses microorganisms already present in the environment to biodegrade harmful contaminants. No human intervention involved.
• Accelerated bioremediation


  Substrate or nutrients are added to the environment to help break down the toxic spill by making the microorganisms grow more rapidly. Microorganisms are usually indigenous, but occasionally very efficient ones are additionally added.

  
• Biosparging


  Involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater.
• Bioventing


  The most common in situ treatment and involves supplying air and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.
• Types of ex situ bioremediation

  • Land farming
  • Composting
  • Biopiles
  • Bioreactors
  • Anaerobic processes
• Types of phytoremediation


  • Phytoextraction or phytoaccumulation
  • Phytodegradation or phytotransformation
  • Phytostabilization
  • Rhizodegradation
  • Rhizofiltration
• Bioaugmentation


  The addition of naturally occurring microbes to sites. Sites can be treated with high concentrations of specific microbes. Costs little money, time and disruption. Simple testing done for biocompatibility and biodegradation efficiency.
• Biostimulation


  The use of indigenous microbes. The modification of the site to promote the growth of native microbes already present. Depends on necessary native microbial and organic material to be present. Costs little time and money. Testing appropriate microbes can be difficult and complex.
• Accelerated bioremediation


  Adding substrate or nutrients to the environment to help break down the toxic spill by making the microorganisms grow more rapidly
• Microorganisms in accelerated bioremediation


  • Usually indigenous, but occasionally very efficient at degrading a certain contaminant are additionally added
• Biosparging


  Injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria
• Biosparging


  • Increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater