Background - Microbial Discovery Group - Franklin WI



FAQs: Anaerobic, Aerobic, AnoxicBackgroundIn wastewater treatment cells grow until the reach maximum size, and then divide into two in a process called binary fission. This process can happen every 20 to 30 minutes under optimum growth conditions. During cell growth, there are maintenance needs that the bacteria have. These maintenance needs are met through energy released from food molecules. All bacteria have enzymes, which enable them to break down food and pass it through the cell membrane. Respiration: The process of obtaining energy from food molecules which is controlled by enzymes. Enzymes: Protein molecules that each cell makes. Enzymes are needed for all biochemical reactions because they help the cell break down the organic materials so they can go through the cell membrane (outer wall of the cell). Synthesis: An energy consuming reaction that results in the production of new biomassEndogenous Respiration: When synthesized biomass and storage products become the energy source for the reaction. This decreases the amount of biomass present. Aerobic Respiration2540001543050Aeration TankAeration Tank25400063500This is how BOD is removed in activated sludge. Oxygen is the final electron receptor in these reactions. Sources of energy (food) include carbohydrates, and proteins. End products of aerobic respiration include water, energy, and carbon dioxide. Aerobic: Free dissolved oxygen is presentAerobic Organisms: These organisms only have enzyme structures capable of functioning in aerobic environmentsAnaerobic RespirationAnaerobic respiration occurs in the absence of free dissolved oxygen. Oxygen is still required for respiration, but is derived from nitrate (NO3-), Sulfate (S04-2) and Carbonate (CO3-2)Bound Oxygen MoleculeEnd ProductNitrateNitrogen GasSulfateHydrogen SulfideCarbonateMethaneWhat’s the difference between Anoxic and Anaerobic?Anaerobic: A condition in which free of combined oxygen is not availableAnoxic: A condition in which oxygen is available in combined forms only While technically anaerobic, reactions that involve using inorganic electron acceptors (nitrate and sulfate) are often referred to as anoxicTypes of OrganismsAerobic Organisms: Use aerobic respiration onlyAnaerobic organisms: Use anaerobic respiration onlyFacultative Organisms: Can use both aerobic and anaerobic respiration. They will use aerobic respiration in the presence of free dissolved oxygen. ReferencesActivated Sludge Processes, METC Group Incorporated, 1999Operation of Municipal Wastewater Treatment Plants, Volume II: Liquid Processes Sixth Edition, WEF ................
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