The objective of this paper is to present an experimentally validated mechanistic model to predict the oxygen transfer rate coefficient (Kla) in aeration tanks for different water temperatures. Using experimental data created by Hunter and Vogelaar, the formula precisely reproduces experimental results for the standardized Kla at 20 °C, comparatively better than the current model used by ASCE 2...

The present study reports the effects of aeration and agitation on growth and production of the cyclosporin A (CyA) in batch fermentor cultures of Tolypocladium inflatum MTCC 557. Dissolved oxygen concentration, pH, dry cell wt, CyA titer and sugar utilization were continuously measured and determined. In the first step, the effect of agitation was evaluated by changing the agitation speed in t...

ABSTRACT The possibility of damage due to the phenomenon cavitation leads design stepped spillways considering maximum specific discharges 15 30 m2/s, a limit considerably lower than that practiced on smooth chutes. Aerators promote insertion air in flow, allowing for increase flow rates. This work analyzes pressures vertical faces steps and entrainment coefficient through an experimental study...

Aeration devices are introduced along chute spillways and at bottom outlets to prevent cavitation damage in high velocity flows. Bottom aerators are characterised by large quantities of air entrained along the jet interfaces but also by a strong de-aeration process near the impact of the water jet with the spillway bottom. In this paper, the aeration and de-aeration occurring respectively in th...

Models were developed for prediction and interpretation of the observed steady-state axial dissolved oxygen concentration profiles in tall airlift bioreactors. The observed concentration profiles were non-linear because of a combination of hydrodynamic and mass transport factors. The profiles were influenced mainly by the liquid-phase axial dispersion coefficient, the volumetric overall gas–liq...

Aeration experiments were conducted in two rectangular surface aeration tanks of L/B ratios 1.5 and 2 along with a square tank (L/B=1) to study their relative performance due to shape on oxygen transfer process while re-aerating the same volume of water such that the cross-sectional area of all the three tanks is the same. An identical rotor with six flat blades was used in all the three tanks....

Ten biomass samples from both municipal and industrial pilot and full scale submerged membrane bioreactors (MBRs) with mixed liquor suspended solids concentrations (MLSS) ranging from 7.2 to 30.2g L(-1) were studied at six air-flow rates (0.7, 1.3, 2.3, 3, 4.4 and 6m(3)m(-3)h(-1)). Statistical analyses were applied to identify the relative impacts of the various bulk biomass characteristics on ...

Production, viscosity, and chemical composition of xanthan synthesized by bacterium Xanthomonas campestris pv pruni strain 101 were evaluated in bioreactor systems. During the process, the volumetric oxygen mass transfer coefficient (k(L)a) and the biomass were determined and the pH was monitored. The cultures were grown in a 3 I bioreactor, with aeration and agitation varying as follows: condi...