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Bioremediation

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					BIOREMEDIATION
   BY SEHREEN ASHRAF
 ENVIROMENTAL
BIOTECHNOLOGY
  ENVIROMENTAL BIOTECHNOLOGY
• Concerned with applications of biotechnology in
  environmental protection, since rapid industrialization
  and urbanization has resulted in a threatened cleaned
  environment
            Soil contamination
• Typically arises from
   o The rupture of underground storage tanks
   o Application of pesticides
   o Percolation of contaminated surface water to subsurface strata
   o  Oil and fuel dumping
   o Leaching of wastes from landfills or direct discharge of industrial wastes to the
     soil.
   o Intensities of chemical usage.
                  Cont……
• The concern over soil contamination stems primarily
  from health risks, from direct contact with the
  contaminated soil, vapors from the contaminants, and
  from secondary contamination of water supplies within
  and underlying the soil.
  Affects of soil pollution on
           Ecology
• Alteration of metabolism of endemic microorganisms and
  arthropods resident in a given soil environment. The result
  can be virtual eradication of some of the primary food chain,
  which in turn have major consequences for predator or
  consumer species
• Concentration of persistent DDT materials for avian
  consumers, leading to weakening of egg shells, increased
  chick mortality and potential extinction of species.
• Contaminants typically alter plant metabolism, most
  commonly to reduce crop yields.
              Cleanup options

   Excavate soil and take it to a disposal site.
   Thermal remediation.
   Chemicals
   Bioremediation
BIOREMEDIATION
             Bioremediation
• Any process that uses microorganisms, fungi, green
  plants or their enzymes to return the natural
  environment altered by contaminants to its original
  condition.

• An example of a more general approach is the cleanup
  of oil spills by the addition of nitrate and/or sulfate
  fertilizers to facilitate the decomposition of crude oil by
  indigenous or exogenous bacteria.(Alaska oil spill 1989)
                    HISTORY
• Invented by george M. Robinson, petroleum engineer for
  santa maria, california.
• Desalination of agricultural land by phytoextraction has
  a long tradition
• 600BC, ancient Roman's utilization of microorganisms
  to treat their waste water.
                  TYPES

• ON THE BASIS OF TREATMENT SITE:

  o IN SITU
  o EX SITU
       In situ bioremediation
• Latin and means “in its original place”.

• Involves treating the contaminated material at the site
   o Biostimulation is the addition of nutrients, oxygen or other electron donors and
     acceptors to the coordinated site in order to increase the population or activity of
     naturally occurring microorganisms available for bioremediation.
   o Bioaugmentation the addition of microorganisms that can biotransform or
     biodegrade contaminants.
                    TECHNIQUES
o Bioventing
   o pumping air into the soil above the water table
o Injection of hydrogen peroxide
   o Oxygen can be provided by delivering the oxygen in liquid
     form as hydrogen peroxide.
o Biosparging
   o Injection of air below the water table  increases
     groundwater oxygen concentrations and mixing in
     saturated zone
BIOVENTING
BIOSPARGING
          DISADVANTAGE
• May not work well in clays or in highly layered
  subsurface environments because oxygen cannot
  be evenly distributed throughout the treatment
  area.
• Often requires years to reach cleanup goals,
  depending mainly on how biodegradable
  specific contaminants are
                              EX SITU
• Involves the removal of the contaminated material to be
  treated elsewhere.
• Ex situ techniques include :
   o slurry-phase bioremediation
       • Contaminated soil is combined with water and other additives in a large
          tank called a "bioreactor"
   o solid-phase bioremediation.
       • Land farming
       • Composting
       • Soil biopiles
                 Land Farming
• Is a bioremediation treatment process that is performed in the upper
  soil zone. Contaminated soils, sediments, or sludges are
  incorporated into the soil surface and periodically turned over
  (tilled) to aerate the mixture.
                Composting
• Based on the stimulation of
  the biodegradative activity of
  microbial populations present
  in a contaminated soil, by
  means of the addition of
  a compost.
                               BIOIPILES
•   Excavated soils are mixed with soil amendments, placed on a treatment area, and
    bioremediated using forced aeration.
•   The basic biopile system includes a treatment bed, an aeration system, an
    irrigation/nutrient system and a leach ate collection system. Moisture, heat,
    nutrients, oxygen, and pH are controlled to enhance biodegradation. The
    irrigation/nutrient system is buried under the soil to pass air and nutrients either by
    vacuum or positive pressure.
•   Treatment time is typically 3 to 6 months .
   TYPES OF
BIOREMEDlATI0N
              TYPES OF
           BIOREMEDlATI0N
• Bacterial Remediation
• Mycoremediation
• Phytoremediation
  BACTERIAL REMEDIATION
• Using bacteria to break down molecular contaminants
  like hydrocarbons into simpler, safer components.

• It can be accomplished by culturing (breeding) bacteria
  in high numbers and then introducing them into a
  contaminated area.
              Mycoremediation

•Using fungi to degrade or
sequester contaminants in the
environment
•Certain strains have been
reported to successfully
degrade the nerve gases VX and
sarin
•Oyster mushrooms, soil
contaminated with diesel
   Phytoremediation
           Term coined in 1991

Using a plant species which is resistant to
   or tolerates a particular contaminant
Resistant plants are usually located
   growing on soils with underlying metal
   ores or on the boundary of polluted
   sites.
 5 types based on the fate of contaminants
PHYTOEXTRACTION
  (to accumulate contaminants into the roots and shoots or leaves)
PHYTOTRANSFORMATION
  (their transformation to more stable, less toxic, or less mobile form.)
PHYTOSTABILIZATION
   (constituents are adsorbed and bound into the plant structure)
PHYTODEGRADATION
   (is the breakdown of contaminants through the activity existing in the
  rhizosphere)
RHIZOFILTRATION
  (water remediation technique that involves the uptake of contaminants by
  plant roots)
ADVANTAGES &
DISADVANTAGES
              ADVANTAGES
• More economical than more traditional methods

• Cost one-third to one-half that of incineration

• Reducing the risk exposure to cleanup personnel and
  potentially wider exposure
                  CONT……
• Minimal environmental impact, since bioremediation is
  a natural process

• Waste products are usually not generated, as
  bioremediation often results in complete degradation of
  the contaminants
           DISADVANTAGES
 In order for organisms to successfully reduce pollutant
  levels, their population must increase.
 Controlling these conditions may prove difficult,
  particularly as conditions may vary so greatly among
  sites.
 Labor required to maintain optimal conditions may be
  extensive
                 CONT……..
 The environment may contain substances or organism
  that inhibit growth of the degrading population.

 Bioremediation may succeed in completely removing a
  given pollutant only to generate another possibly toxic
  by-product,; for instance, conversion of TNT to amines or
  azoxy dimers during composting
RESEARCH
                         RESEARCH
• Genetically engineered microbes
  (GEM)
   o Deinococcus radiodurans, that is resistant to radiation
     damage
   o Bacillus infernos which can resist high temperatures
   o Methanococcus jannaschii , which can resist high
     pressures (up to 230 atm) in addition to high
     temperatures.
   o Dehalococcoides have the natural ability to
     dechlorinate tri-, tetra- and penta-chloro dioxins
   o Bioluminescence
 Pseudomonas fluorescens
         HK44
• The university of tennessee in
  collaboration with oak ridge national
  laboratory has achieved the first, and so
  far only, field release of a GEM for
  bioremediation purposes
• Bioluminescence
• A reporter for naphthalene
  bioavailability
• functions as a continuous online
  monitoring tool for bioremediation
  process.
     LAND MINE DETECTION
• Alistair Elfick and the team introduced
  the gene for an enzyme called luciferase,
  which naturally produces light in some
  bacteria and fireflies.
• When proteins on the surface
  of E.coli detect TNT, this "switches on"
  the gene responsible for light
  production.
• the bacteria only show that there are
  landmines in the area, but they cannot
  yet pinpoint the exact locations of them.
Genetically modified plants

• Arabidopsis thaliana has been genetically modified to overexpress
  two bacterial genes, arsC and g-ECS, can take up arsenate, detoxify
  it and store it.
• Tobacco plants have been genetically modified to express bacterial
  pentaerythritol tetanite (PETN) reductase allowing these plants to
  take up high-energy compounds and reduce them to non-explosive
  substances
• Transgenic poplars (Populus) over expressing a mammalian cytochrome
  P450, a family of enzymes commonly involved in the metabolism of toxic
  compounds
                      Techniques
• Bioremediation of diesel-contaminated soil by heated and
  humidified biopile system in cold climates, David Sanscartier ,
  Barbara Zeeb, Iris Koch, Ken Reimer
• Fluorescence in situ hybridization (FISH), in situ PCR, and
  quantitative PCR are expected to be powerful tools for bioremediation to
  detect and enumerate the target bacteria that are directly related to
  the degradation of contaminants.
• Denaturing gradient gel electrophoresis (DGGE) andterminal
  restriction fragment length polymorphism (T-RFLP), enable us to
  monitor the changes in bacterial community in detail.
Practical implication of
    Bioremediation
    Practical implication of
        Bioremediation
• At the Scott Lumber Company Superfund site in Missouri,
  16,000 tons of soils contaminated with polyaromatic
  hydrocarbons (PAHs) were biologically treated using land
  treatment application. PAH concentrations were reduced by
  70%.
• At the French Ltd. Superfund site in Texas, slurry-phase
  bioremediation was used to treat 300,000 tons of lagoon
  sediment and tar-like sludge contaminated with volatile
  organic compounds, semi-volatile organic compounds,
  metals, and pentachlorophenol. Over a period of 11 months,
  the treatment system was able to meet the cleanup goals set
  by EPA.
o Water hyacinths used to remove
  arsenic from water supplies in
  Bangladesh, India




                        o Sunflowers used to remove
                          radioactive cesium and strontium
                          from Chernobyl site

				
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