Mass transfer coefficient

About: Mass transfer coefficient is a research topic. Over the lifetime, 7827 publications have been published within this topic receiving 168354 citations.

Mass transfer versus kinetic control of uptake across solid‐water boundaries

Abstract: We present general nondimensional solutions for uptake across a solid-water boundary, considering the combined influences of mass transfer flux limitation and uptake reaction kinetics. Mass transfer processes are represented by a general mass transfer velocity. Reaction kinetics are represented by first-order and Monod models. Mathematical solutions are well approximated by standard mass transfer models for low values of the derived nondimensional mass transfer velocity and by standard kinetic models for high values. Approximate limiting values of the nondimensional mass transfer velocity are defined for mass transfer control and kinetic control. The intermediate region, where both mass transfer and kinetics influence the solution, is relatively broad for first-order kinetics and Monod kinetics in oligotrophic environments. Both limits decrease as concentration increases in the Monod solution, such that under increasingly eutrophic conditions mass transfer control becomes less important, the intermediate range shrinks, and kinetic control becomes an increasingly good approximation. Example calculations using data from experimental ecosystems indicate that boundary nutrient uptake was mass transfer controlled or intermediate under oligotrophic conditions. Nutrient pulses applied to the systems caused temporary eutrophication, which resulted in temporary kinetic control.

Biomass Characteristics, Aeration and Oxygen Transfer in Membrane Bioreactors: Their Interrelations Explained by a Review of Aerobic Biological Processes

Abstract: Abbreviations: a - gas-liquid interfacial area based on aerated liquid volume (L )1 ); K - mass transfer coefficient (L t )1 ); kL - gas-liquid mass transfer coefficient (L t )1 ); kLa - overall volumetric gas-liquid mass transfer coefficient (t )1 ); a - ratio of kLa in process water to clean water; a kLa - characteristic of the aeration capacity (t )1 ); g - viscosity (L )1 Mt )1 ); Unit dimensions: L - length; M - mass; t - time Abstract Membrane bioreactor (MBR) is a promising alternative to conventional wastewater treatment methods However this process is still under-used due to its high running costs Its main power requirement comes from aeration, which is used to supply dissolved oxygen to the micro-organisms and to maintain the solids in suspension In addition, in submerged MBRs, aeration is used for membrane cleaning A complex matrix links the biomass characteristics, the aeration and the oxygen transfer These parameters can impact on each other and/or delete one another effect In order to understand the phenomena occurring in MBRs, similar aerobic biological processes, such as fermentation, mineral industry and slurry, were investigated This review discusses the interrelations of the biomass characteristics (solids concentration, particle size and viscosity), the aeration intensity and the oxygen transfer in MBRs

A film-diffusion-based adsorption kinetic equation and its application

Abstract: A convenient adsorption kinetic equation based on film diffusion mass transfer and Langmuir equilibrium was developed. The model shows a straight line passing through the origin in a plot similar to the Boyd plot and the slope of the line is related to the film mass transfer coefficient. It can be used to analyze if an adsorption process is controlled by film diffusion and, if so, to determine the film mass transfer coefficient. The model was applied to four adsorption systems and compared with the Weber, the Boyd (or Reichenberg) and the Vermeulen (or Urano) models.