Chapter 3E - Oxidation and Reduction PDF

OXIDATION AND REDUCTION PROCESS IN BIOREMEDIATION  REQUIREMENTS FOR BIOREMEDIATION MICROORGANISMS ENERGY ELECTRON SOURCE ACCEPTOR MOISTURE pH NUTRIENTS TEMPERATURE ABSENCE OF REMOVAL OF ABSENCE OF TOXI...

OXIDATION AND REDUCTION PROCESS IN BIOREMEDIATION  REQUIREMENTS FOR BIOREMEDIATION MICROORGANISMS ENERGY ELECTRON SOURCE ACCEPTOR MOISTURE pH NUTRIENTS TEMPERATURE ABSENCE OF REMOVAL OF ABSENCE OF TOXICITY METABOLITES COMPETITIVE ORGANISMS BIOREMEDIATION  The Role Of Contaminant, Microorganisms, Electron Acceptor And Donor In Bioremediation. Role of Contaminants: Acting as a carbon source and energy source Supplying the simple units for forming cellular components of new cells. Role of Microorganisms : Responsible for degrading the contaminants. The contaminants are degraded into simple units and involve energy transfer. The simple units are later used to synthesize components for the new cells, e.g., cell membrane, cell wall, DNA, etc. The energy was used for bond formation in new cellular components for the new cells. Biodegradation will end up with the formation of many new cells, i.e. increase in biomass. Role of Electron Acceptor and Donor: The contaminants act as the electron donor, whilst carbon dioxide is the electron acceptor. Redox reaction will occur between the electron donor and the Electron donor:Terminal/final electron The relative organic matteracceptor: energy yield of using different (CH2O) ultimate destination for terminal electron electrons acceptors for respiration.  REDOX (oxidation-reduction) reactions play a key role in energy flow through organisms This is because the electrons flowing from one molecule to another are carrying energy with them Metabolism is the sum of all of the chemical reactions in an organism: catabolic (breakdown) Energy Transfer: Energy is found in the bonds between atoms Oxidation is a decrease in the energy content of a molecule Reduction is the increase in the energy content of a molecule Oxidation-reduction reactions are always coupled within the body, i.e. whenever a substance is oxidized, another is almost simultaneously reduced.  CO2 O2 (ELECTRON H2O ACCEPTOR) TO GENERATE Breakdown ENERGY of contaminant oxidation Microorganis an increased population of ms microorganisms.” with the rest of the carbon used to produce Organic contaminant new cell mass (cell SOURCE OF BIOMASS) NUTRIENT AND (C, H, O) (C, H, O, P)) (C, H, O,N)  1 Metabolism Functions of Food source of energy essential nutrients Metabolism is all the chemical reactions of the body. some reactions produce the energy stored in ATP that other reactions consume all molecules will eventually be broken down and recycled or excreted from the body CONTAMINANTS: ELECTRON DONORS: ELECTRON DONORS:  Chlorinated solvents  Benzene, toluene, Ethenes (PCE, TCE) ethylbenzene and Ethanes (TCA) xylene (BTEX) Methanes (CT)  Methyl tert-butyl ether (MTBE)  Perchlorate  Tert-Butyl Alcohol  Hexavalent Cr (TBA)  Explosives (TNT, TDX, HMX)  Nitrates (NO3-)  Radionuclides (TcO4-, UO2+2)  Acid mine drainage  AEROBIC MICROBES FINAL CARBON ANAEROBIC ELECTRON MICROBES SOURCE: ACCEPTOR: FINAL ORGANIC CARBON OXYGEN ELECTRON CARBON SOURCE: ACCEPTOR: FACULTATIVE MICROBES ORGANIC SULFATE OR CARBON CARBON FINAL DIOXIDE CARBON ELECTRON SOURCE: ACCEPTOR: ORGANIC NITRATES, CARBON IRON, AND MANGANESE  AEROBIC RESPIRATION ELECTRON DONOR ELECTRON END PRODUCT (CARBON SOURCE) ACCEPTOR Organic substrates O2 CO2, H2O (benzene, toluene, phenol) NH4 O2 NO2- , NO3- , H2O Fe2+ O2 Fe3+ S2- O2 SO-  ANAEROBIC RESPIRATION ELECTRON ELECTRON END PRODUCT DONOR(CARBON ACCEPTOR SOURCE) Organic substrates NO3- N2, CO2, H2O, Cl- (benzene, toluene, phenol, trichloroethylene) Organic substrates SO42- S2- , CO2, H2O, Cl- (benzene, trichloroethylene) H2 SO42- S2-, H2O H2 CO2 CH4, H2O  FERMENTATIO N ANAEROBIC Electron donor: Electron ORGANISMS organic acceptor: organic FINAL compounds compounds CARBON ELECTRON End-products SOURCE: ACCEPTOR: (depend on ORGANIC SULFATE OR CARBON microorganisms): CARBON Acids DIOXIDE Alcohols Ketones Gases: CO2 , CH4  Anaerobic respiration Aerobic bioremediation: microbial reactions that require oxygen to go Anaerobic bioremediation: A microbial forward. The bacteria reaction occurring in the absence of use a carbon substrate oxygen and involving many processes, including fermentation, methanogenesis, as the electron donor reductive dechlorination, and sulfate and and oxygen as the nitrate reducing conditions. In anaerobic electron acceptor. metabolism, nitrate, sulfate, carbon dioxide, oxidized materials, or organic compounds may replace oxygen as the