A transient mathematical model for maximum respiration activity and oxygen diffusion coefficient estimation in non-steady-state biofilms

1998 ◽  
Vol 73 (3) ◽  
pp. 274-280 ◽  
Author(s):  
Artem Khlebnikov ◽  
Falilou Samb ◽  
Paul Péringer
Keyword(s):  
Mathematical Model ◽  
Diffusion Coefficient ◽  
Steady State ◽  
Oxygen Diffusion ◽  
Respiration Activity ◽  
Oxygen Diffusion Coefficient ◽  
Coefficient Estimation

Use of a dynamic gassing-out method for activity and oxygen diffusion coefficient estimation in biofilms

1998 ◽  
Vol 37 (4-5) ◽  
pp. 171-175
Author(s):  
Artem Khlebnikov ◽  
Falilou Samb ◽  
Paul Péringer
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Uptake ◽  
Oxygen Diffusion ◽  
Fixed Bed ◽  
Biofilm Reactor ◽  
Strictly Aerobic ◽  
Comamonas Testosteroni ◽  
Respiration Activity ◽  
Oxygen Diffusion Coefficient ◽  
Biofilm Development

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.

Electronic/Ionic Conductivity and Oxygen Diffusion Coefficient af the Sr-Fe-Co-O System

1995 ◽  
Vol 393 ◽  
Author(s):  
B. Ma ◽  
J.-H. Park ◽  
C. U. Segre ◽  
U. Balachandran
Keyword(s):  
Diffusion Coefficient ◽  
Ionic Conductivity ◽  
Oxygen Diffusion ◽  
Ionic Conductivities ◽  
Transference Number ◽  
Transference Numbers ◽  
Oxygen Diffusion Coefficient ◽  
Ionic Transference Number ◽  
Local Fitting ◽  
Oxide Ion

ABSTRACTOxides in the Sr-Fe-Co-O system exhibit both electronic and ionic conductivities. Recently, the Sr-Fe-Co-O system attracted great attention because of its potential to be used for oxygen-permeable membranes that can operate without electrodes or external electrical circuitry. Electronic and ionic conductivities of two compositions of the Sr-Fe-Co-O system, named SFC-1 and SFC-2, have been measured at various temperatures. The electronic transference number is much greater than the ionic transference number in SFC-1, whereas the electronic and ionic transference numbers are very similar in SFC-2. At 800°C, the electronic and ionic conductivities are ≈76 and ≈4 S•cm−1, respectively, for SFC-1; whereas, for SFC-2, the electronic and ionic conductivities are ≈10 and ∼1 S•cm−1, respectively. By performing a local fitting to the equation σ • T = Aexp(-Ea / kT), we found that the oxide ion activation energies are 0.92 and 0.37 eV, respectively, for SFC-1 and SFC-2. The oxygen diffusion coefficient of SFC-2 is ≈ 9 x 10−7cm2/sec at 900°C.

Temperature dependence of oxygen diffusion and consumption in mammalian striated muscle

1993 ◽  
Vol 264 (6) ◽  
pp. H1825-H1830 ◽  
Author(s):  
T. B. Bentley ◽  
H. Meng ◽  
R. N. Pittman
Keyword(s):  
Diffusion Coefficient ◽  
Steady State ◽  
Oxygen Diffusion ◽  
Striated Muscle ◽  
Effect Of Temperature ◽  
Retractor Muscle ◽  
Oxygen Solubility ◽  
Order Of Magnitude

This study investigated the effect of temperature on the oxygen diffusion coefficient (DO2) of hamster retractor muscle from 11 to 37 degrees C. DO2 was measured using a non-steady-state technique, whereas muscle O2 consumption (VO2) was estimated after steady state was reached. DO2 was 0.84 +/- 0.04 x 10(-5) cm2/s at 11 degrees C and rose exponentially to 2.41 +/- 0.19 x 10(-5) cm2/s at 37 degrees C, producing a temperature coefficient for DO2 of 4.60%/degrees C for this temperature range. To measure DO2 directly at 37 degrees C, it was necessary to inhibit tissue VO2 with Amytal. The DO2 measurements made at 37 degrees C were significantly higher than previously reported values, which had been based on extrapolations from lower temperatures (6). Further analysis suggests a possible transition in the diffusion pathway between 23 and 30 degrees C, resulting in a DO2 higher than that previously expected. This larger DO2, together with a recently published value of oxygen solubility (alpha) (21), results in an in vitro Krogh's diffusion coefficient (KO2) that is 2.4 times larger than that previously reported (24) and therefore significantly reduces an order of magnitude discrepancy between in vitro and estimated in vivo KO2 values (24). Muscle VO2 was 0.35 ml O2.min-1.100 g-1 at 11 degrees C and increased with temperature, resulting in an activation energy of the rate-limiting reaction from the Arrhenius equation of -10.5 kcal/mol between 11 and 30 degrees C.

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