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Nora Ruizordaz - One of the best experts on this subject based on the ideXlab platform.

  • biodegradation of 2 4 6 trichlorophenol in a packed bed biofilm reactor equipped with an internal net draft tube riser for aeration and Liquid Circulation
    Journal of Hazardous Materials, 2009
    Co-Authors: Gomezde A Jesus, F J Romanobaez, L Leyvaamezcua, Cleotilde Juarezramirez, Nora Ruizordaz, Juvencio Galindezmayer
    Abstract:

    Abstract For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for Liquid Circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A D / A R ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values ɛ G , and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies (≈95%), and by the stoichiometric release of chloride ions from the halogenated compound (≈80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions).

  • a novel split cylinder airlift reactor for fed batch cultures
    Bioprocess and Biosystems Engineering, 2001
    Co-Authors: Juvencio Galindezmayer, O Sanchezteja, Eliseo Cristianiurbina, Nora Ruizordaz
    Abstract:

    Conventional airlift reactors are not adequate to carry out variable volume processes since it is not possible to achieve a proper Liquid Circulation in these reactors until the Liquid height is higher than that of the downcomer. To carry out processes of variable volume, the use of a split-cylinder airlift reactor is proposed, in the interior of which two multi-perforated vertical baffles are installed in order to provide several points of communication between the reactor riser and downcomer. This improves the Liquid Circulation and mixing at any Liquid volume.

Juvencio Galindezmayer - One of the best experts on this subject based on the ideXlab platform.

  • biodegradation of 2 4 6 trichlorophenol in a packed bed biofilm reactor equipped with an internal net draft tube riser for aeration and Liquid Circulation
    Journal of Hazardous Materials, 2009
    Co-Authors: Gomezde A Jesus, F J Romanobaez, L Leyvaamezcua, Cleotilde Juarezramirez, Nora Ruizordaz, Juvencio Galindezmayer
    Abstract:

    Abstract For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for Liquid Circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A D / A R ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values ɛ G , and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies (≈95%), and by the stoichiometric release of chloride ions from the halogenated compound (≈80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions).

  • a novel split cylinder airlift reactor for fed batch cultures
    Bioprocess and Biosystems Engineering, 2001
    Co-Authors: Juvencio Galindezmayer, O Sanchezteja, Eliseo Cristianiurbina, Nora Ruizordaz
    Abstract:

    Conventional airlift reactors are not adequate to carry out variable volume processes since it is not possible to achieve a proper Liquid Circulation in these reactors until the Liquid height is higher than that of the downcomer. To carry out processes of variable volume, the use of a split-cylinder airlift reactor is proposed, in the interior of which two multi-perforated vertical baffles are installed in order to provide several points of communication between the reactor riser and downcomer. This improves the Liquid Circulation and mixing at any Liquid volume.

R Z Tudose - One of the best experts on this subject based on the ideXlab platform.

  • Hydrodynamics of non-Newtonian Liquids in external-loop airlift bioreactors. Part 2 : Study of the Liquid Circulation velocity
    Bioprocess Engineering, 1998
    Co-Authors: Maria Gavrilescu, R Z Tudose
    Abstract:

    In order to obtain further information on the behaviour and optimal design of external-Circulation-loop airlift bioreactors, the Liquid circulating velocity was studied using highly viscous pseudoplastic solutions of starch and antibiotic biosynthesis Liquids of Penicillium chrysogenum, Streptomyces griseus, Streptomyces erythreus, Bacillus licheniformis and Cephalosporium acremonium. Measurements of Liquid Circulation velocity were made in laboratory and pilot plant external-loop airlift bioreactors, under various conditions concerning gas flow rate, riser Liquid height at constant downcomer height, A D /A R ratio, using the impulse-response technique. It has been found that these parameters had a significant effect on Liquid Circulation velocity together with the apparent viscosity and dry weight of the solid phase in the biosynthesis Liquids. For the tested Liquids, the superficial Liquid velocity in the riser section of an external-loop airlift bioreactor may be described by the following equation: V SLR = CV SGR a (A D /A R ) b (H s /H D ) C (η ap /η W ) d C e s , where the exponents and the constant c take different values depending on the Liquid phase properties and flow regime.

  • Modelling of Liquid Circulation velocity in concentric-tube airlift reactors
    Chemical Engineering Journal, 1998
    Co-Authors: Maria Gavrilescu, R Z Tudose
    Abstract:

    Abstract A mathematical model for riser Liquid superficial velocity in a concentric-tube airlift reactor is proposed. The model is based on an energy balance incorporating acceleration coefficients to quantify deviations from ideal flow. The acceleration coefficients at the draft-tube and downcomer entrance are determined experimentally, based on static pressure profile measurements. The model could predict Liquid velocities over a broad range, including an almost 50-fold variation of Liquid Circulation velocity and a four-fold change in reactor height. The model predictions agreed with the measurements to within ± 28%.

  • Concentric-tube airlift bioreactors. Part II: Effects of geometry on Liquid Circulation
    Bioprocess Engineering, 1998
    Co-Authors: Maria Gavrilescu, R Z Tudose
    Abstract:

    Liquid Circulation velocity was investigated in three concentric-tube airlift reactors of different scales (RIMP, V L = 0.07 m 3 ; RIS-1, V L = 2.5 m 3 ; RIS-2, V L =5.20 m 3 ). The effects of top and bottom clearance and resistance in flow pathway at downcomer entrance on the riser Liquid superficial velocity, the Circulation time, the friction coefficient and flow radial profiles of the gas holdup and the Liquid superficial velocity in riser, using water-air as a biphasic system, were studied. It was found that the riser Liquid superficial velocity is affected by the analyzed geometrical parameters in different ways, depending on their effects on the pressure loss. The riser Liquid superficial velocity, the friction coefficient and the parameters of the drift-flux model were satisfactorily correlated with the bottom spatial ratio (B), gas separation ratio (Y) and downcomer flow resistance ratio (A d /A D ), resulting empirical models, with correlation coefficients greater than 0.85.

  • study of the Liquid Circulation velocity in external loop airlift bioreactors
    Bioprocess Engineering, 1995
    Co-Authors: Maria Gavrilescu, R Z Tudose
    Abstract:

    Liquid Circulation velocity was studied in externalloop air-lift bioreactors of laboratory and pilot scale, respectively for different gas input rates, downcomer-to-riser cross-sectional area ratio, AD/AR and Liquid phase apparent viscosities.

  • Study of the Liquid Circulation velocity in external-loop airlift bioreactors
    Bioprocess Engineering, 1995
    Co-Authors: Maria Gavrilescu, R Z Tudose
    Abstract:

    Liquid Circulation velocity was studied in externalloop air-lift bioreactors of laboratory and pilot scale, respectively for different gas input rates, downcomer-to-riser cross-sectional area ratio, A _D/A_R and Liquid phase apparent viscosities. It was found that, up to a gas superficial velocity in the riser v _SGR ≈ 0.04 m/s the dependency of v _SLR on v _SGR is in the following form: v _SLR = a v _SGR ^b , with the exponent b being 0.40. Over this value of v _SGR, only a small increase in Liquid superficial velocity, v _SLR is produced by an increase in v _SGR. A _D/A_R ratio affects the Liquid superficial velocity due to the resistance in flow and overall friction. For non-Newtonian viscous Liquids, the Circulation Liquid velocity in the riser section of the pilot external-loop airlift bioreactor is shown to be dependent mainly on the downcomer-to-riser cross-sectional area ratio, A _D/A_R, the effective (apparent) Liquid viscosity, η _eff and the superficial gas velocity, v _SGR. The equation proposed by Popovic and Robinson [11] was fitted well, with an error of ± 20%.

Zhen Min Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Determination of Liquid multiscale Circulation structure in a bubble column by tracing the Liquid flowing trajectory
    Industrial and Engineering Chemistry Research, 2011
    Co-Authors: Zi Bin Huang, Zhen Min Cheng
    Abstract:

    To identify the Liquid Circulation flow structure in a bubble column, a set of multipoint tracer injection and detection device was developed for a systematic study in a bubble column of 550 cm in height and SO cm in diameter. Tracer response profiles were measured to track the Liquid flowing trajectory under various flow conditions in the column with and without draft tubes. They showed that only when the draft tube length was greater than 3 m could the tracer response exhibit obvious periodicity. To resolve the Liquid Circulation flow structure in the time and frequency domain, wavelet rnultiresolution analysis was adopted. The results showed that the Liquid Circulation frequency increased with superficial gas velocity, which is in agreement with the published literature. It was also found that the macroscale, mesoscale, and microscale Circulation loops coexisted in the bubble column.

  • Backmixing reduction of a bubble column by interruption of the global Liquid Circulation
    Industrial and Engineering Chemistry Research, 2009
    Co-Authors: Zhen Min Cheng, Yang Wu, Zi Bin Huang
    Abstract:

    The strong backmixing of the Liquid phase which is prevalent in a bubble column should be ascribed to its global Circulation which is upward in the central region while downward near the wall on the reactor scale. To suppress the backmixing behavior, interruption of the Liquid Circulation route should be effective. To verify this presumption, an investigation was conducted with a bubble column 550 cm in height and 50 cm in diameter, which was equipped with four channels of the same size installed at different heights so as to cut the downward motion of the Liquid and therefore prevent the global Circulation the Liquid. It shows that although the radial velocity distribution of the Liquid remains parabolic in the short column constituted by two neighbor channels, the velocity profile tends to be flat in the upward direction as the channel is approached. The residence time distribution analysis shows that the backmixing of Liquid could be reduced by 60% when four channels 12 cm in diameter were applied. 1.

Yoshinori Kawase - One of the best experts on this subject based on the ideXlab platform.