A novel multiple-airlifting membrane bioreactor is built with four sintered stainless steel tubular filters as the risers and downcomers. This work investigates the hydrodynamics including gas holdup, liquid velocity, liquid circulation and mixing times by aerating different number of risers (one to three) at superficial gas velocities of 0.02–0.07m/s The mass transfer phenomena, including oxyg...

Three different aeration plates are used to study their effect on gas holdup and flow regime transition in fiber suspensions. The aeration plates differ by their open-area ratios (A=0.57%, 0.99%, and 2.14%), where the hole diameter remains the same while the number of holes increase. Experiments are performed using three different Rayon fiber lengths (L=3, 6, and 12mm) over a range of superfici...

In airlift reactors transport phenomena are achieved by pneumatic agitation and circulation occurs in a defined cyclic pattern through a loop. In the present work, the effect of geometrical relations on gas holdup and liquid velocity, and consequently on the gas-liquid mass transfer coefficient, was studied in a 6liter airlift bioreactor with AD/AR = 0.63; AD, downcomer cross-sectional area, an...

The gas holdup and flow dynamics in a laboratory scale Rushton-turbine flotation tank were simulated using the dispersed k- turbulence model and Eulerian-Eulerian multiphase modelling approach. The inherent uncertainties in the CFD predictions were quantified by examining the model and numerical (i.e., discretization) uncertainties. The contribution of model uncertainty was explored by conside...

The main objective of this paper is to examine the effect of nanomaterials on mass transfer coefficient in bubble type absorption of carbon dioxide by experiment. The absorption process is carried out in a bubble column and in room temperature. Mass transfer coefficient, saturated concentration of CO2, and gas holdup are determined in this system. The kinds of nanomaterials, the concentrations ...

Lu Han and Muthanna H. Al-Dahhan A gaseous tracer technique and procedures were developed and implemented to measure the axial dispersion of gas phase in a slurry bubble column reactor using air-water-glass beads (100ìm). Residence time distribution curves were obtained by measuring the response of gaseous tracer pulse input. The gas phase axial dispersion coefficient, Dg, was determined from m...

The application of Gas-Liquid-solid circulating fluidized beds (GLSCBE) has increased recently in chemical, petrochemical and biochemical industries. Electrical Resistance Tomography (ERT) and optical fibre probe were applied to investigate local phase holdups distribution. Since ERT is applicable only to conductive phase(s), e.g. liquid phase in this study, optical fibre probe was employed sim...

Gas holdup and mixing time were characterized in a forced circulation internal loop draft-tube reactor (unaerated aspect ratio≈ 6, downcomero-riser cross-sectional area ratio = 0.493) as functions of the forced liquid superficial velocity in the riser (ULr) and the gas superficial velocity in he riser (UGr). Data were obtained in air–water system. The operation ranges were 0≤ULr ≤ 0.051 m/s and...

Experiments were performed in a cylindrical 0.14 m diameter bubble column with a metal perforated plate. Air and aqueous solutions of glycerol with viscosity 1–22 mPa s were the phases. Gas holdup was measured and plotted against the gas flow rate. The critical point where the homogeneous–heterogeneous regime transition begins was determined by the drift-flux plot of the primary data. The homog...

Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentif...