MICROBIAL BIOREMEDIATION AND FOOD SAFETY

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MICROBIAL BIOREMEDIATION AND FOOD SAFETY
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Green revolutionIndustrial revolutionBrown
fieldsNearly 1,00,000 human made chemicals are
added in last 50 yearsApproximately 1000 new
chemicals are added every year
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Sources of pollutionFarm lands with excess
pesticidesand inorganic fertilisersIndustrial
pollutantsSpillages, leakages during handling
and production or use of industrial
materialsMining and oil drillingDisposal sites
and dump yards
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Bioremediation

• Destruction of contaminants by biological
  mechanisms, including microorganisms (e.g. yeast,
  fungi or bacteria), and plants.
• Removal and reduction of man made pollution of
  environment

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Microorganisms in Bioremediation of soil

• Bacteria Achromobacter, Acinetobacter,
  Alcaligenes, Arthrobacter, Bacillus
• Fungi - Rhodotorula, Mortierella, Aspergillus and
  Penicillium.
• Trichoderma etc.
• Phenerochaete chrysosporium has wide degradative
  capacity due to production of lignases which
  utilize peroxide.

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Microbes in Bioremediation

• BACTERIA TAKE UP LARGE AMOUNTS OF METALS AND
  MINERALS
• BACTERIA CONVERT Hg, Cr, Se etc. TO VOLATILE
  ELEMENTAL FORM BY REDUCTION AND BY CHANGING
  THEIR OXIDATION STATE
• BACTERIA AND ALGAE PRODUCE SECRETIONS THAT
  ATTRACT METALS THAT ARE TOXIC AT HIGH LEVELS
• FUNGI DEGRADE POLYAROMATIC CHEMICALS LIKE LIGNIN
• FUNGI METHYLATE As, Se TO GASSEOUS FORM
• ALGAE AND PLANTS GOOD IN ABSORBING N, P, S,
  MINERALS, METALS FROM THE ENVIRONMENT

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DEGRADATION OF POLLUTANTS BY MICROBES

• METABOLISM OF CONTAMINANT TO
• CELL MASS, CARBON DIOXIDE AND WATER - AEROBIC
  CONDITIONS
• CARBON DIOXIDE, METHANE, HYDROGEN TRACES.,
  SULFIDES, NITREOGEN GAS DEPENDING ON PRESENCE OF
  ELECTRON ACCEPTORS
• ANAEROBIC CONDITIONS
• COMETABOLISM OF CONTAMINANT TO
• NON TOXIC COMPOUNDS BY ENZYMES PRODUCED WITH
  METHANE UTILIZATION BY METHYLOTROPHS

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MICROBIAL GENES CODE FOR DEGRADATIVE ENZYMES FOR

• OXIDATION
• REDUCTION
• DEHALOGENATION
• DEALKYLATION
• DEAMINATION
• HYDROLYSIS
• METHYLATION ETC.
• OF THE POLLUTANTS INTO
• NON TOXIC ENDPRODUCTS

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METHODS OF BIOREMEDIATION
BIOSTIMULATION BIOAUGMENTATION BIOFILTERS
BIOREACTORS BIOVENTING COMPOSTING LAND
FARMING PHYTOREMEDIATION
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BIOAUGMENTATION

• Addition of organisms or enzymes to a material to
  remove unwanted chemicals
• Bioaugmentation is used to remove byproducts
  from raw materials and potential pollutants from
  waste.
• Bacteria are the most common bioaugmentation
  organisms.

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BIOFILTERS

• The removal of organic gases by passing air
  through compost or soil containing microorganisms
  capable of degrading the gases.
• Used to remove volatile organic compounds (VOC's)
  from air.

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BIOREACTORS

• The treatment of a contaminated substance in a
  large tank containing organisms or enzymes.
• Bioreactors are commonly used to remove toxic
  pollutants from solid waste and soil.

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BIOSTIMULATION

• The use of nutrients or substrates to stimulate
  the naturally occurring organisms that can
  perform bioremediation.
• Fertilizer and growth supplements are the common
  stimulant.
• The presence of small amounts of the pollutant
  can also act as a stimulant by turning on operons
  for the bioremediation enzymes.

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BIOVENTING

• Involves the venting of oxygen through soil to
  stimulate the growth of natural and introduced
  bioremediation organisms.
• Used predominantly for soils contaminated with
  petroleum products.
• Not suitable for removing halogenated gases that
  contribute to ozone layer damage.

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COMPOSTING

• Mixing contaminated materials with compost
  containing bioremediation organisms.
• The mixture incubates under aerobic and warm
  conditions.
• The resultant compost can be used as a soil
  augmentation or be placed in a sanitary landfill.
  

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LANDFARMING

• The use of farming tilling and soil amendment
  techniques to encourage the growth of
  bioremediation organisms in a contaminated area.
• Used successfully to remove large petroleum
  spills in soil.

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PHYTOREMEDIATION the use of plants to remove or
transform contaminants

• Plant hyper-accumulating metals (direct action).
• Plants stimulating microbes in rhizosphere
  (indirect action).
• Microbes in soil with soybean plants mineralised
  TCE twice as fast as soil without plants

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IN-SITU BIOREMEDIATION

• This involves the use of organisms or enzymes
  to remove pollutants in the location that is
  polluted.
• Cheaper as no excavation, transportation,
  labourer charges involved.
• The average time frame for In-situ bioremediation
  is 12 to 24 months hence needs longer time.
• Ground water pollution due to contaminant
  mobility is possible

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EX-SITU BIOREMEDIATION

• This involves the removal of contaminated
  material where it can be treated using
  bioremediation.
• Better control over area, depth, nutrients,
  oxygen, moisture, temp etc.
• The average time frame for Ex-situ
  bioremediation is 60 to 90 days hence faster
  compared to In situ Bioremediation
• Use of liners prevent ground water pollution
  Costlier as excavation of soil, transportation,
  labour cost , Space requirements etc.

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FACTORS INFLUENCING BIOREMEDIATION
Presence of microorganims with pollutant
degradative capability Depth, Area, and
Concentration of contamination Soil
factors Organic matter content and nutrient
level pH and texture of soil Permeability and
water holding capacity Compettition for oxygen
and presence of other electron acceptors
Presence of toxic compounds for microbes
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LIMITATIONS IN BIOREMEDIATION

• Cleanup goals may not be attained if the soil
  matrix prohibits contaminant-microorganism
  contact. 
• The circulation of water based solutions through
  the soil may increase contaminant mobility and
  necessitate treatment of underlying ground water.
• Preferential colonization by microbes may occur
  causing clogging of nutrient and water injection
  wells.

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Preferential flow paths may severely decrease
contact between injected fluids and contaminants
throughout the contaminated zones. The system
should not be used for clay, highly layered, or
heterogeneous sub-surface environments because of
oxygen (or other electron acceptor) transfer
imitations.Ø  High concentrations of heavy
metals, highly chlorinated organics, long chain
hydrocarbons, or inorganic salts are likely to be
toxic to microorganisms.Ø  Bioremediation slows
at low temperatures.
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ENHANCED BIOREMEDIATION

• Enhanced bioremediation is a process in which
  indigenous or inoculated micro-organisms (e.g.,
  fungi, bacteria, and other microbes) degrade
  (metabolize) organic contaminants found in soil
  and/or ground water, converting them to innocuous
  end products.
• Nutrients, oxygen, or other amendments may be
  used to enhance bioremediation and contaminant
  desorption from subsurface materials.

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Enzyme based Bioremediation

• HCZyme approved by EPA
• Contains no bacteria or enzymes
• Treatment of Hydrocarbons and
• chlorinated hydrocarbons
• 1 lit Conc. HCZyme per 6 cubic meter of soil per
  five weeks treatment
• costed US 15 to 50 per Cubic meter
• Helped in removing contaminants

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GENETICALLY ENGINEERED MICRO-ORGANISMS

• Fuel
• Volatile oranic compounds
• Semi volatile organic compounds
• Pesticides
• Bioremediation changes valence state of
  inorganics and cause adsorption, immobilisation
  to soil particles
• Pptation, uptake, accumulation and concentration
  of inorganics in microorganisms macroorganisms

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St. Gabriel Louisiana US plant site Ciba Giegy
Corpn

• 19000 Cubic meter Atrazine contaminated soil in
• 8 hectares of Biological Clean up unit
• LAND FARMING Ploughing a 4 times a Week
• BIOSTIMULATION 880 Kg fertiliser/H PK(131313)
• BIOAUGMENTATION 2000 L Pseudomonads culture
• Initial Atrazine Conc. 100 mg/Kg of soil
• After 20 weeks Atrazine conc. 10 mg/Kg of soil
• Cost of Bioremediation US 1,050,000
• For lifting and dumping US 5,300,000
• At waste disposal unit

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Soil Degradation Data

• A three week pilot project was conducted on soil
  samples extracted from the site.
• Heterotrophic populations increased from
  1,500,000 to 150,000,000 colony forming units
  (CFU)/gram.
• Soil concentrations were degraded from 1,543 ppm
  to 562 ppm.

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Three week pilot test dataSoil concentrations
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Heterotrophic populations
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Extended pilot test data

• TPH soil concentrations dropped below 100 mg/Kg
  for a 93.7 reduction in 50 days

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Pilot test data
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Successful Bioremediation Programs

• Bioremediation was the method of treatment opted
  to treat 1500 cubic yards of diesel contaminated
  soil at the former Kings Truck Stop in
  Sacramento, CA.
• The project reduced the diesel contaminant levels
  from 3000 PPM to less than 30 PPM in
  approximately 62 treatment days.

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In situ bioremediation was necessary to clean up
contamination from a ruptured transfer line that
led to a loss of 300 to 400 gallons of solvent at
a depth of 38 inches beneath the surface along
120 feet of the track.A continuously
recirculating ground injection system was
designed and installed to treat the contaminated
soil. Following a clean up program of nine months
with the bioaugmented system, a 99.5 degradation
of the contaminants was achieved ( Table ).
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Table
Component 09/24/84 10/31/84 04/04/85 RED
Chemical (ppb) (ppb) (ppb) (ppb)
Benzene N/A 96 31 67.7
Carbon Tet N/A 65 Nil 99.9
Chlorobenzene 9,050 227 37 99.6
1,1 DCE N/A 508 341 32.9
Ethyl Benzene 154,000 1,119 382 99.8
Toluene 31,000 1.276 526 98.3
111 TCA N/A 82 Nil 99.9
Xylene 1,249,000 16,825 1,979 99.8
N/A not analyzed for
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A bioremediation project involving 32,000 cubic
yards of soil contaminated with various
lubrication and form oils is indicated that the
contamination levels have been reduced from a
high of 1800 PPM down to 125 PPM in the most
contaminated cell. In a lesser contaminated
cell, the levels have been taken from 1400 PPM
down to below the action level of 100 PPM. 
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COUNTRIES AND RELATIVE COSTS OF BIOREMEDIATION

• USA, UK, BRAZIL, FRANCE, NIGERIA ETC.
• IN USA 75000 SITES 1100 BILLION US
• IN EUROPE -495000 SITES- 1000 BILLION US
• BIOREMEDIATION COST US 52-131/cubic m
• INCINERATION US 327-1046
• LAND FILLING US 196-327
• USA BIOREMEDIATION MARKET IS AROUND 10-15 BILLION
  US AND
• ANNUAL GROWTH RATE IS ABOUT 10-15 PER YEAR

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The microbes will have the last wordLouis
PasteurFather of Microbiology