Respiration endogenous

For a soluble wastewater, the net sludge to be wasted from the process may be computed as synthesis minus oxidation, ie, endogenous respiration. 

Endogenous respiration A reduced level of respiration (breathing) in which organisms break down compounds within their own cells to produce the oxygen they need. 

Biological growth is the result of the coupled synthesis-endogenous respiration reactions. The net result can be expressed as... 

Endogenous respiration reactions also occur, which reduce the sludge formation ... 

If Ss is not present in sufficient concentration, Xbw is used for endogenous respiration. 

The biomass is not effective throughout the whole cycle therefore, the process time (tP) is therefore the effective duration (tE) with respect to heterotrophic growth and endogenous respiration (Artan, 2001). 

In principle, there are two possible ways to measure this effect. First, there is the end-point measurement (steady-state mode), where the difference is calculated between the initial current of the endogenous respiration and the resulting current of the altered respiration, which is influenced by the tested substances. Second, by kinetic measurement the decrease or the acceleration, respectively, of the respiration with time is calculated from the first derivative of the currenttime curve. The first procedure has been most frequently used in microbial sensors. These biosensors with a relatively high concentration of biomass have a longer response time than that of enzyme sensors. Response times of comparable magnitude to those of enzyme sensors are reached only with kinetically controlled sensors. 

If, for example, a waste volume, K of 10,000 gal with a ppm COD of 1500 is processed in t = 20 hr, the equilibrium sludge weight is 270 lb. The calculation is oversimplified and is about 10% too low, assuming, as it does, that endogenous respiration and assimilation occur simultaneously during the entire operation. Actually, there is always a retention time during which cellular substance is consumed without replenishment. 

Hoover, S. R., Jasewicz, L. and Porges, N. 1952A. Biochemical oxidation of dairy wastes. IV. Endogenous respiration and stability of aerated dairy waste sludge. Sewage Ind. Wastes 24, 1144-1149. 

The constant kd is referred to as the endogenous respiration coefficient or the specific maintenance rate. Pirt(45) points out that kd is proportional to m, the maintenance coefficient defined in equation 5.51 ... 

At high growth rates the endogenous respiration rate has little net effect on the formation of biomass but in continuous culture with low nutrient levels then endogenous respiration becomes significant and has to be included in the expression for growth rate. 

Temperature is recognised as having an effect on the growth yield, the endogenous respiration rate and the Monod kinetic parameters Ks and pm. Within the temperature range of 25 to 40°C these have been shown to have dependencies which could be accounted for by Arrhenius-type exponential equations (Topiwala and Sin-CLAIR<52)). If the temperature-dependent nature of the constants has to be taken into account, equation 5.70 must be written as ... 

A limitation of the methods described so far is that they have assumed a constant overall yield coefficient and do not allow the endogenous respiration coefficient kd (or alternatively the maintenance coefficient, m) to be evaluated. Equation 5.54 shows that the overall yield, as measured when monitoring a batch reactor, is affected by the growth rate and has the greatest impact when the growth rate is low. Consequently, it is desirable to be able to estimate the values of kd or m, so that the yield coefficient reflects the true growth yield. An equivalent method would be one where the specific rates of formation of biomass and consumption of substrate were determined independently, again without the assumption of a constant overall yield-coefficient. 

However, inspection of Fig. 5.57 suggests that the operation of a chemostat at dilution rates other than those approaching washout conditions results in growth at low values of substrate concentration S. For this condition the endogenous respiration rate becomes significant and Ya Yx/S, as indicated in equation 5.54. It therefore becomes more realistic to express the specific growth rate p as ... 

The steady-stale substrate and biomass concentrations for a continuous stirred-tank fermenter operated at various dilution rates are given below. Given that the fresh feed concentration is 700 mg/l, calculate the values of the Monod constants and Ks the yield coefficient, Y and the endogenous respiration coefficient kd. 

S. G. Curnutt and R. R. Schmidt (1964b). Possible mechanisms controlling the intracellular level of inorganic polyphosphate during synchronous growth of Chlorella pyrenoidosa. Endogenous respiration. Exp. Cell. Res., 36, 102-110. 

The energy-dependent uptake, which by definition is sensitive to uncoupler, is supported by endogenous respiration and low concentra-... 

Here, V is the averaging volume and VB(t) is the volume of phase B within the averaging volume. The parameters sA and eB are the volume fractions of the phases A (eA = VA/V) and B (eB = VB/V), respectively. The parameter Dje is the effective diffusivity tensor of component Ji max e is the maximum reaction rate, and r/n is the first-order endogenous respiration rate coefficient. The cell mass per unit volume of biofilm is defined by... 

These new cells may be further oxidized during endogenous respiration as follows ... 

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