Oxygen Monitoring from Aerobic and Anaerobic for determination of biodegradation kinetics by respirometry - Monitoring and Testing - Health and Safety Monitoring and Testing

Intrinsic kinetic tests involve adding relatively high concentrations of organic substrate to small concentration of acclimated microorganisms so that the COD/VSS ratio typically is greater than 10. Kinetic parameters are then determined by non-linear modeling using well-known relationships between biological growth and oxygen uptake.

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In this example, 700 mg/L of glycerin COD was added to a test culture containing 45 mg/L of active biomass. Modeling showed the following kinetic parameters: Yield coefficient, Yg = 0.42 mg VSS/mg COD removed; specific substrate conversion rate, qm = 0.35 mg COD/mg VSS/hr; specific growth rate, μmax = 0.10 g VSS/g VSS-hr.

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Extant kinetic tests involve adding relatively low concentrations of organic substrate to large concentrations of biomass so that the COD/VSS ratio usually is less than 0.1. Extant kinetic parameters are then determined by using non-linear modeling techniques. Examples are shown below:

In this example case, 600 mg/L of acetate was added to a test culture containing 2000 mg VSS/L, followed by measurement of oxygen uptake by respirometers. Modeling showed the following: Active biomass = 390 mg/L; yield coefficient, Yg = 0.45 mg VSS/mg COD removed; specific substrate conversion rate, qm = 0.33 mg COD/mg VSS/hr; specific growth rate, μmax = 0.15 g VSS/g VSS-hr; biomass decay rate (active basis), b = 0.01/hr; half-saturation coefficient, K¬S = 1 mg/L. The shaded zone represents oxygen uptake associated with biodegradation of biopolymer that was stored in the original seed biomass.