Bi oremediation


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Bi oremediation

  1. 1. Bioremediation The Natural Way to Reduce pollution Presented By: Tenzin Dolma BMS 2nd Year SRCASW, DUPresentaion@ Tenzin Dolma 1
  2. 2. Introduction The use of bacteria and fungi and plants tobreak down or degrade toxic chemicalcompounds that have accumulated in theenvironment at excess levels to bring them tonormal levels which are considered acceptable.It involves :(1) a minor change in an organic molecule leaving the main structurestill intact (2) fragmentation of a complex organic moleculein such a way that the fragments could be reassembled to yield theoriginal structure (3) complete mineralization Presentaion@ Tenzin Dolma 2
  3. 3. The release of the pollutants can be• Deliberate and well regulated (industrial emissions)• Accidental and largely unavoidable (chemical/oil spills) Presentaion@ Tenzin Dolma 3
  4. 4. What Makes Bioremediation a Promising Approach?•Permanence , the waste are completely degraded• Low cost, 60-90% less than other technologies Two Ways of Metabolization Presentaion@ Tenzin Dolma 4
  5. 5. In situ Ex situ• Relies on indigenous microbial • Ex-situ Bioremediation requires fauna of subsurface soil and pumping of the groundwater or ground water. The microbes at excavation of contaminated soil the contaminated site can prior to remediation treatments. degrade the waste. • It suffers from costs associated• Degradation continues till a limit problems with solid handling but we can add nutrients and is process e.g. excavation, called “enhanced insitu screening and fractionation, bioremediation.” mixing, homogenizing and final• Eg. Exxon Valdez oil spill Alaska disposal. (i) solid-phase system (including land treatment and soil piles) i.e. composting, and (ii) slurry-phase systems (involving treatment of solid-liquid suspensions in bioreactors). Presentaion@ Tenzin Dolma 5
  6. 6. Requirem ents forBiorem ediation: Microbes Energy Electron Source Acceptor Moisture pH Nutrients Temperature Absence Of Absence Of Removal Of Competitive Toxicity Metabolites Bacteria Bioremediation Presentaion@ Tenzin Dolma 6
  7. 7. Above groundbioreactors• Same technology as fermenters. Treats excavated soil or ground water with high levels of contaminants.• Contaminated soil+ water= slurry Reactor• Bacterial inoculum may be from indigenous indigenous site, activated sludge or sewage.• Genetically engineered organisms are used. Bioreactors can be used in series to accomplish the degradation. Presentaion@ Tenzin Dolma 7
  8. 8. Land Farming• Pretreated or untreated oily sludge from refinery wastes mixed with soil is subjected to insitu bioremediation.• Conditions: Flat landfarm, light and loamy soil for proper aeration , clay layer to prevent ground water seepage. Temperature and precipitaion is foreseen too. ( 20 to 30 degree)• Inorganic fertilizers are applied to raise the pH to about 7.8.• Cons: Slow and incomplete, Heavy metal accumulation, the land farm used intensively can’t be used for agriculuture and livestock grazing later. Presentaion@ Tenzin Dolma 8
  9. 9. Composting• It is the emerging trend with a low cost in decontaminating the soils which were wasted with discharges from explosive industries. Alternative to incineration.• Anaerobes can degrade RDX and HMX.• Example: Desulfovibrio species use the explosives as N source , Klebsiella pneumoniae degrades RDX to CO2, H20 and formaldehyde.• Degradation of 90%..80 days, 55 degree celsius . In 150 days, 18000mg to 74 mg per kg.• Eg. Desulphovibrio species( RDX and HMX), Klebsiella pneumoniae (RDX) Presentaion@ Tenzin Dolma 9
  10. 10. Super Bug•Oil spills cause devastation to the environmentkilling sea life, birds, and coastal plants.Spraying areas of contamination with oil-eatingmicrobes accelerates the degradation of the oil.•The very first superbug was created byChakrabarty and co-workers reported thedevelopment of a new strain of bacterium bytransfer of plasmids and named it superbugwhich could utilize a number of toxic organicchemicals like octane, hexane, xylene, toluene,camphor and naphthalene. This superbugmaking it the first genetically engineeredmicroorganism to be patented. This superbugwas then used for cleaning an oil spill in Texasin 1990.• Eg. Alcanivorax borkumensis, Deinococcusradiodurans, Pseudomonas putida Presentaion@ Tenzin Dolma 10
  11. 11. Phytoremediation• Phytoremediation is the use of plants to clean up potentially damaging spills. The plants work with soil organisms to transform contaminants, such as heavy metals and toxic organic compounds, into harmless or valuable forms.• ≈350 plant species naturally take up toxic materials• Sunflowers used to remove radioactive cesium and strontium from Chernobyl site• Water hyacinths used to remove arsenic from water supplies in Bangladesh, India• Transgenic plants as Arabidopsis thaliana hybrids are used. Presentaion@ Tenzin Dolma 11
  12. 12. Mycoremediation:• Mushroom mycelium release enzymes that can break the chemical bonds of many petrochemicals and toxins. Some mushrooms can also uptake heavy metals—they must then be harvested and treated as toxic waste. Different species work best for specific toxins.• A substrate, often wood chips, sterilized straw or cardboard, is inoculated with mushroom spawn of a beneficial species. Inoculated substrate can also be used as a filter for flowing water. Some Presentaion@ Tenzin Dolma species 12 of fungi will attack
  13. 13. Pros and Cons• Prosi. Inexpensive methodii. No maintenance expenses and aesthetically pleasing• Consi. Only surface soil (root zone) can be treatedii. Clean up take several years Presentaion@ Tenzin Dolma 13
  14. 14. Thank you!!! Presentaion@ Tenzin Dolma 14
  15. 15. References• Alexdaner N.Glazer and Hiroshi Nikaido , Microbial Biotechnology, 2nd Edition• Microbes and Society, Benjamin S. Weeks• Prescott microbiology, McGraw-Hill Presentaion@ Tenzin Dolma 15