Hydrodynamics and local parameters in three-phase-flow in airlift-loop reactors of different scale

Kochbeck, Birgit; Lindert, Mark; Hempel, D. C.

doi:10.1016/0009-2509(92)85056-h

Cited by 26 publications

(6 citation statements)

References 5 publications

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“…Geometric dimensions and scale-up investigations on these airlift-loop reactors have been described elsewhere. 25,26 Three di †erent types of carrier particles were used for cell immobilization. Characteristic data of the solid matrices are given in Table 2.…”

Section: Methodsmentioning

confidence: 99%

Biological degradation of EDTA: reaction kinetics and technical approach

Henneken

Nörtemann

Hempel

1998

J. Chem. Technol. Biotechnol.

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: The microbial mineralization of EDTA in waste water by a mixed culture was studied with suspended and immobilized cells. Efficient degradation of EDTA could be achieved, though the chelator is stated not to be biodegradable. A complete set of kinetic parameters was determined that enables the modelling of EDTA degradation and, related to this, bacterial growth, ammonium release, maintenance requirement as well as oxygen uptake. In order to obtain important technical scale-up parameters, the microorganisms were immobilized on di †erent carrier particles and employed in continuously operated three-phase airlift-loop reactors. The reactors could be operated at a dilution rate up to D \ 1É2 h~1 that, at an EDTA concentration of 450 mg dm~3, led (D ? k ' ) to EDTA degradation rates up to 12É8 kg m~3 day~1. The extent of EDTA degradation remained constant at 95È99% with increasing values of D. Achieved kinetic parameters of the bioÐlm systems were compared with those which were obtained from experiments with suspended cells.

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Section: Methodsmentioning

confidence: 99%

Biological degradation of EDTA: reaction kinetics and technical approach

Henneken

Nörtemann

Hempel

1998

J. Chem. Technol. Biotechnol.

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“…Determinations of the Degree of Liquid Mixing and Mixing Time. Many researchers used an axial dispersion model to describe the overall mixing phenomena in airlift reactors (Frohlich et al, 1991; Kochbeck et al, 1992). The mathematical expression can be shown as…”

Section: Methodsmentioning

confidence: 99%

Liquid Mixing in Internal Loop Airlift Reactors

Lu¹,

Hwang²,

Chang³

1994

Ind. Eng. Chem. Res.

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Liquid mixing in the riser and downcomer of two-and three-phase internal loop airlift reactors as well as the overall liquid mixing were studied. Tracer was injected into the airlift reactors, and pH sensors were employed to measure the variations of tracer concentration in the riser, downcomer, top, and bottom sections. The Bo number in individual sections of the airlift reactors were obtained by time domain analysis of these concentration variations. It was found that the degree of mixing in the riser was higher than that in the downcomer. Moreover, mixing in the two-phase system was superior to that in the three-phase system, and the degree of mixing of the calcium alginate system was lower than that of the polystyrene system. Minimum values of the overall axial dispersion coefficient existed in the relationship between the overall axial dispersion coefficient and solids loading.

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“…Then it almost keeps constant with increasing superficial gas velocity. Because of the flow resis- tance increase with increasing solid holdup [14], the energy consumed by the flow increases and the liquid velocity decreases with increasing solid holdup. Klein et al [15] also found that the liquid velocity decreases with increasing solid holdup.…”

Section: Liquid Velocitymentioning

confidence: 99%