MICROBIAL BIOREMEDIATION
AND FOOD SAFETY
Green revolution
Industrial revolution
Brown fields
Nearly 1,00,000 human made
chemicals are added in last 50
years
Approximately 1000 new
chemicals are added every year
Sources of pollution
Farm lands with excess pesticides
and inorganic fertilisers
Industrial pollutants
Spillages, leakages during handling
and production or
use of industrial materials
Mining and oil drilling
Disposal sites and dump yards
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
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.
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
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
MICROBIAL GENES CODE FOR
DEGRADATIVE ENZYMES FOR
OXIDATION
REDUCTION
DEHALOGENATION
DEALKYLATION
DEAMINATION
HYDROLYSIS
METHYLATION ETC.
OF THE POLLUTANTS INTO
NON TOXIC ENDPRODUCTS
METHODS OF BIOREMEDIATION
BIOSTIMULATION
BIOAUGMENTATION
BIOFILTERS
BIOREACTORS
BIOVENTING
COMPOSTING
LAND FARMING
PHYTOREMEDIATION
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.
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.
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.
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.
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.
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.
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.
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
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
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.
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
LIMITATIONS IN BIOREMEDIATION
 Cleanup goals may not be attained
if the soil matrix prohibits contaminantmicroorganism 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.
 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.
 High concentrations of heavy metals, highly
chlorinated organics, long chain hydrocarbons, or
inorganic salts are likely to be toxic to
microorganisms.
 Bioremediation slows at low temperatures.
ENHANCED BIOREMEDIATION
Enhanced bioremediation is a process
in which indigenous or inoculated microorganisms (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.
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
GENETICALLY ENGINEERED MICROORGANISMS
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
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(13:13:13)
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
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.
Three week pilot test data
Soil
concentrations
1,600
TPH, ppm
1,400
1,543
1,200
1,000
800
600
562
400
290
200
0
Day 0
Day 14
Day 21
Heterotrophic populations
115,000,000
Plate count No.
120,000,000
100,000,000
80,000,000
49,000,000
60,000,000
40,000,000
20,000,000
1,900,000
0
Day 0
Day 14
Day 21
Extended pilot test data
 TPH soil concentrations dropped
below 100 mg/Kg for a 93.7 %
reduction in 50 days
Pilot test data
1,600
1,543
TPH, mg/kg
1,400
1,200
1,000
720
800
562
600
390
290
400
97
200
0
0
14
21
27
35
50
Successful Bioremediation
Programs
Bioremediation was the method of
treatment opted to treat 1500 cubic
yards of diesel contaminated soil at the
former King’s 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.
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 ).
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
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.
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 1015 BILLION US $ AND
ANNUAL GROWTH RATE IS ABOUT 10-15 %
PER YEAR
The microbes will have
the last word
Louis Pasteur
Father of Microbiology