microbial bioremediation and food safety green revolution industrial revolution brown fields nearly...
TRANSCRIPT
MICROBIAL BIOREMEDIATION AND FOOD
SAFETY
Green revolutionIndustrial revolutionBrown fieldsNearly 1,00,000 human made chemicals are added in last 50 yearsApproximately 1000 new chemicals are added every year
Sources of pollution
Farm lands with excess pesticidesand inorganic fertilisersIndustrial pollutantsSpillages, leakages during handling and production or use of industrial materialsMining and oil drillingDisposal 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 BioremediationBACTERIA 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
OXIDATIONREDUCTIONDEHALOGENATIONDEALKYLATIONDEAMINATION HYDROLYSISMETHYLATION ETC.OF THE POLLUTANTS INTONON 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 BioremediationUse of liners prevent ground water pollution Costlier as excavation of soil, transportation, labour cost , Space requirements etc.
FACTORS INFLUENCING BIOREMEDIATIONPresence 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 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.
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 BIOREMEDIATIONEnhanced 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.
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 MICRO-ORGANISMS
FuelVolatile oranic compoundsSemi volatile organic compoundsPesticidesBioremediation 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
1,543
562
290
0
200
400
600
800
1,000
1,200
1,400
1,600
TP
H, p
pm
Day 0 Day 14 Day 21
Heterotrophic populations
1,900,000
115,000,000
49,000,000
0
20,000,000
40,000,000
60,000,000
80,000,000
100,000,000
120,000,000
Pla
te c
ount
No.
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
1,543
562
290390
720
97
0
200
400
600
800
1,000
1,200
1,400
1,600
TP
H, m
g/kg
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 $ 196-327USA BIOREMEDIATION MARKET IS AROUND 10-15 BILLION US $ AND ANNUAL GROWTH RATE IS ABOUT 10-15 % PER YEAR
The microbes will have the last word
Louis PasteurFather of Microbiology