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K.v. Radha - One of the best experts on this subject based on the ideXlab platform.
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Gas–liquid mass transfer studies in inverse fluidized bed biofilm reactor for the biodegradation of industrial effluent rich in phenolic compounds
Environmental Progress, 2015Co-Authors: S. Sabarunisha Begum, K.v. RadhaAbstract:Gas–liquid mass transfer studies were carried out in inverse fluidized bed biofilm reactor (IFBBR) for the biodegradation of phenol. Studies were done to analyze the effect of Superficial Air Velocity (Ug), gas holdup (ɛg), and biofilm characteristics such as biofilm thickness, biofilm dry density, suspended and attached biomass concentration, and bioparticle density on oxygen transfer rate (OTR) and gas–liquid volumetric mass transfer coefficient (kLa) for different Superficial Air velocities and various particle sizes (2.9, 3.5, and 3.8 mm). Average OTR and kLa was found to be high [(OTR)avg. = 0.0159 min−1; (kLa)avg.= 1.8823 g/(L min)] for the particle size of 3.5 mm at the optimum Superficial Air Velocity (Ugm) of 0.220 m/s which created high turbulence with smaller bubble size. Higher volumetric mass transfer coefficient and OTR resulted in higher percentage of Chemical Oxygen Demand (COD) removal (98%) and phenol degradation (100%) in IFBBR. The gas holdup dominated over the smaller size bubbles resulting in higher mass (oxygen) transfer rate. Thin, dense, and stable biofilm was produced at Ugm. Above Ugm, thickness of the biofilm was increased where the detachment force did not control the outgrowth of biofilm anymore and thus the kLa was found to be decreasing. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 433–438, 2016
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Effect of gas–liquid mass transfer coefficient and liquid–solid mass transfer resistance on phenol biodegradation in three phase inverse fluidized bed biofilm reactor
Journal of environmental chemical engineering, 2014Co-Authors: S. Sabarunisha Begum, K.v. RadhaAbstract:Abstract Studies were done to analyze the effects of gas–liquid volumetric mass transfer coefficient ( k L a) and liquid–solid mass transfer resistance ( ϕ ) for different Superficial Air Velocity on various support particle sizes (2.9, 3.5 and 3.8 mm) in inverse fluidized bed biofilm reactor (IFBBR) for the biodegradation of phenolic effluent. Oxygen transfer rate (OTR) and k L a was found to be high ((OTR) avg. = 0.0159 g/(L min); ( k L a) avg. = 1.8823 min −1 ) for the particle size of 3.5 mm at the optimum Superficial Air Velocity ( U gm ) of 0.220 m/s which created high turbulence with small bubble size. The gas holdup dominated over the smaller size bubbles resulting in higher oxygen transfer rate. The diffusion effects of biofilm on liquid–solid external mass transfer were studied in IFBBR. The results revealed that smaller size particle had lesser biofilm thickness with dense and stable biofilm. The dense biofilm had higher biofilm dry density which decreased the diffusivity ( D e ) of phenol into the biofilm. In this study, the values of effectiveness factor ( η ) for the particle size of 2.9, 3.5 and 3.8 mm were found to be 0.052, 0.507 and 0.882 respectively. For the particle size of 2.9 mm, the η value was much less than one, so the degradation was found to be diffusion limited. For the particle size of 3.5 and 3.8 mm, η was not much less than one implying that the degradation was due to diffusion and reaction limited rather than diffusion limited alone.
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Effect of hydrodynamic characteristics on the performance of biofilm for degrading phenol in inverse fluidized bed biofilm reactor
Desalination and Water Treatment, 2014Co-Authors: S. Sabarunisha Begum, K.v. RadhaAbstract:AbstractThe influence of some hydrodynamic effects on the performance of biofilm in inverse fluidized bed biofilm reactor (IFBBR) was studied with low-density polystyrene support particles of various sizes (2.9, 3.5, and 3.8 mm) using Pseudomonas fluorescens for the degradation of phenol. The biofilm reactor was operated under different Superficial Air velocities for a fixed settled bed height of particles to study the effect of hydrodynamics on biofilm thickness, biofilm dry density, bioparticle density, and attached and suspended biomass concentrations for efficient biodegradation of phenol. There is evidence that the chemical oxygen demand reduction and phenol degradation efficiency were found to be high at the optimized Superficial Air Velocity with controlled biofilm thickness and for a stable and dense biofilm dry density. The results of the study revealed that with increase in Superficial Air Velocity, the biofilm thickness and bioparticle density decreases while the biofilm dry density and suspend...
Zennosuke Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Effect of particle fluidization intensity on floating and sinking of objects in a gas-solid fluidized bed
Advanced Powder Technology, 2004Co-Authors: Jun Oshitani, Makoto Ijiri, Zennosuke TanakaAbstract:Abstract The floating and sinking of different density spheres in a gas-solid fluidized bed was investigated by changing the Superficial Air Velocity, bed height, particle diameter and sphere diameter. Vertical shaking of the fluidized bed surface was observed under these experimental conditions to evaluate particle fluidization intensity. Those observations were compared with the results of sphere floating and sinking. Small spheres of diameter = 4:76 mm tended to drift in the fluidized bed without floating or sinking with increasing Superficial Air Velocity. However, the spheres easily floated and sank when the bed height or particle diameter was small even if the Superficial Air Velocity was relatively large. Vertical shaking decreased with decreasing Superficial Air Velocity, bed height and particle diameter. Spheres floated and sank according to the density difference when the vertical shaking was less than 1 cm. These results indicate that optimum conditions to reduce particle fluidization intensity should be employed to obtain steady floating and sinking of objects in practice.
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Circulating particle flow and Air bubble behavior at various Superficial Air velocities in two-dimensional gas–solid fluidized beds
Advanced Powder Technology, 2001Co-Authors: Bambang Trisakti, Jun Oshitani, Zennosuke TanakaAbstract:Circulating particle flow and behavior of Air bubbles in a two-dimensional gas-solid fluidized bed of various Superficial Air velocities are investigated by recording videos of movement of a plastic pellet put into the fluidized bed and rising Air bubbles using a video camera. The movement Velocity of the plastic pellet and properties of the Air bubbles such as the bubble rising Velocity and the bubble distribution coefficient, which shows the proportion of the bubbles erupting at the center of the bed surface, are measured by analyzing the videos. It is found that the plastic pellet moves following the circulating particle flow; the particles rise up at the center of a column and fall down near the side walls, and that the movement Velocity increases with the Superficial Air Velocity. The bubble rising Velocity, the apparent erupting bubble size and the bubble distribution coefficient increase, and the bubble eruption frequency slightly decreases, with the Superficial Air Velocity. These results indicate that the circulating particle flow is generated by the rising Air bubbles. In particular, the fact that the Air bubbles rise at the center of the column and coalesce with other bubbles is closely related to the generation of the circulating particle flow.
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Evaluation of fluidized particle flow by measurement of apparent buoyancy
Advanced Powder Technology, 2001Co-Authors: Jun Oshitani, Bambang Trisakti, Zennosuke TanakaAbstract:Abstract Fluidized particle flow is evaluated by the apparent buoyancy acting on a sphere in the fluidized bed. The apparent buoyancy is simply obtained as follows: the weight of the lead sphere is measured at various positions in the fluidized glass beads and the difference between the weight in the fluidized bed and that in the atmosphere is regarded as the apparent buoyancy. The particle flow coefficient α is calculated using the distribution of the apparent buoyancy to show the strength of the particle flow. Measurements are carried out varying the Superficial Air Velocity, the height of the bed, the particle size and the sphere size, and the distributions of the apparent buoyancy and the values of α are compared. It is found that the fluidized particle flow can be simply evaluated by the distributions of the apparent buoyancy and the values of α, and that the difference of the particle flow under various experimental conditions is proved by them, e.g. the circulating particle flow becomes strong as the Superficial Air Velocity increases.
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Material Separation from Automobile Shredder Dust by Gravity Method Using Gas-Solid Fluidized Bed
Journal of The Society of Powder Technology Japan, 2001Co-Authors: Jun Oshitani, Tomoko Kajiwara, Kouji Kiyoshima, Zennosuke TanakaAbstract:Gravity separation of plastic, rubber and wire harness in automobile shredder dust is investigated using a gas-solid fluidized bed. Uni-beads (barium silicatitanate glass), zircon sands and glass beads are employed as fluidized particles. Floating and sinking of plastic, rubber and wire harness in the fluidized bed are examined by changing the Superficial Air Velocity. The wire harness is almost completely separated from the other components by using Uni-beads and zircon sands. The plastic can be separated from the rubber by using glass beads, although the separation efficiency is relatively low. Precise adjustment of Superficial Air Velocity is essential to attain high separation efficiency because the particle flow and Air bubbles in the fluidized bed affect the floating and sinking of the dust.
B. Dietrich - One of the best experts on this subject based on the ideXlab platform.
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Radial two-phase thermal conductivity and wall heat transfer coefficient of ceramic sponges – Experimental results and correlation
International Journal of Heat and Mass Transfer, 2014Co-Authors: M. Wallenstein, Matthias Kind, B. DietrichAbstract:Abstract In this publication, experimental results for the radial two-phase thermal conductivity and the wall heat transfer coefficient of different ceramic sponges (variation of material, porosity and pore size) are presented, revealing a strong influence of the Superficial Air Velocity and of the porosity of the ceramic sponges on both the radial two-phase thermal conductivity and the wall heat transfer coefficient. The experimental data are correlated in dimensionless form to offer a “universal” correlation for estimating the radial two-phase thermal conductivity and the wall heat transfer coefficient of sponges in the future.
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Heat transfer coefficients for solid ceramic sponges – Experimental results and correlation
International Journal of Heat and Mass Transfer, 2013Co-Authors: B. DietrichAbstract:Abstract In this contribution, experimental results about heat transfer coefficients for different ceramic sponges (variation of material, porosity and pore size) are presented. A strong influence of the Superficial Air Velocity and of sponge type properties on the heat transfer is observed. The experimental data is correlated with a Nusselt–Reynolds approach as it is usually done for heat transfer data. Furthermore, the applicability of the analogy between heat and momentum transfer – similar to the Generalized Leveque Equation for packed beds or heat exchangers – is shown. A Nusselt–Hagen correlation has been developed allowing an easy and accurate estimation of heat transfer coefficients for any sponges from pressure drop data. This kind of correlation based on experimental results obtained for many different sponge types is not yet reported in literature.
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Axial two-phase thermal conductivity of ceramic sponges – Experimental results and correlation
International Journal of Heat and Mass Transfer, 2011Co-Authors: B. Dietrich, Matthias Kind, Holger MartinAbstract:Abstract In this publication experimental results for the axial two-phase thermal conductivity of different ceramic sponges (variation of material, porosity and pore size) are presented, revealing a strong influence of the Superficial Air Velocity and of the porosity of the ceramic sponges on the axial two-phase thermal conductivity. The experimental data are correlated in dimensionless form to offer a “universal” equation for calculating the axial two-phase thermal conductivity of sponges in the future.
H M Soliman - One of the best experts on this subject based on the ideXlab platform.
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measurement and correlation of the pressure drop in Air water two phase flow in horizontal helicoidal pipes
International Journal of Multiphase Flow, 1995Co-Authors: A Awwad, Z F Dong, M A Ebadian, H M SolimanAbstract:Abstract Experimental investigations are conducted for Air-water two-phase flow in horizontal helicoidal pipes of varying configurations. The helicoidal pipes are constructed by wrapping Tygon tubing around cylindrical concrete forms. Four different inside diameters of tubing and two different outside diameters of the cylindrical concrete forms are used to make the helicoidal pipe with different configurations. Also, the helix angle of helicoidal pipes varies up to 20 degrees. A total of 32 helicoidal pipes has been tested for the present study. The experiments have been performed for Superficial water Velocity in the range of U L = 0.008–2.2 m/s and Superficial Air Velocity in the range of U G = 0.2–50 m/s. The pressure drop of the Air-water two-phase flow is measured and the data are well correlated. It was found that the pressure drop multiplier relates strongly to the Superficial velocities of Air or water, and that the helix angle has almost no effect on the pressure drop, although the pipe and coil diameters have certain effects in low rates of flow. Correlation for two-phase flow in the horizontal helicoidal pipes has been established based on the present experimental data.
A Prabhakar - One of the best experts on this subject based on the ideXlab platform.
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effect of Superficial Air Velocity on solid state fermentation of palm kernel cake in a lab scale fermenter using locally isolated fungal strain
Industrial Crops and Products, 2009Co-Authors: C W Foong, Jidon Janaun, K Krishnaiah, A PrabhakarAbstract:Solid state fermentation (SSF) is emerging as an attractive alternative to submerged fermentation despite the engineering problems such as removal of metabolic heat, transport of oxygen and moisture into the particles and the heterogeneity of the substrate. In the present work, a lab scale fermenter which can be operated as fluidized bed and packed bed was fabricated. Solid state fermentation of palm kernel cake (PKC) using fungal strain TW1 was carried out at three Superficial Air velocities. PKC particles of mean diameter 855 μm were used and the fluidizing medium was Air. Reducing sugar concentration, biomass growth, bed moisture content, substrate pH, and hemicellulose content were measured. The maximum increase in reducing sugar concentration was at 0.17 m/s since an increase in mannose from 14.55 to 18.63 mg mannose/g dry PKC was observed. The hemicellulose content of this fermented PKC was estimated and the result was around 10% in reduction of hemicellulose content in fermented PKC. Further improvement of PKC bioconversion can likely be achieved by selection of a more robust microbe that can withstand the conditions in the fluidized bed during SSF and by creating a system which can maintain the moisture content of PKC during SSF of PKC throughout the packed bed.
