Presentation on theme: "MICROBIAL BIOREMEDIATION AND FOOD SAFETY Green revolution Industrial revolution Brown fields Nearly 1,00,000 human made chemicals are added in last 50."— Presentation transcript:
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 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 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.
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 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 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 S oil concentrations
Extended pilot test data TPH soil concentrations dropped below 100 mg/Kg for a 93.7 % reduction in 50 days
Pilot test data
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.
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 Component09/24/8410/31/8404/04/85% RED Chemical(ppb) BenzeneN/A Carbon TetN/A65Nil99.9 Chlorobenzene9, ,1 DCEN/A Ethyl Benzene154,0001, Toluene31, TCAN/A82Nil99.9 Xylene1,249,00016,8251, 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 – SITES – 1100 BILLION US $ IN EUROPE SITES BILLION US$ BIOREMEDIATION COST US $ /cubic m INCINERATION US $ LAND FILLING US $ USA BIOREMEDIATION MARKET IS AROUND BILLION US $ AND ANNUAL GROWTH RATE IS ABOUT % PER YEAR
The microbes will have the last word Louis Pasteur Father of Microbiology