Search results for " Oxygen transfer"
showing 3 items of 3 documents
Effect of biomass features on oxygen transfer in conventional activated sludge and membrane bioreactor systems
2019
Abstract The aim of the present study was to compare the oxygen transfer efficiency in a conventional activated sludge and a membrane bioreactor system. The oxygen transfer was evaluated by means of the oxygen transfer coefficient and α-factor calculation, under different total suspended solids concentration, extracellular polymeric substances, sludge apparent viscosity and size of the flocs. The oxygen transfer coefficient and α-factor showed an exponential decreasing trend with total suspended solid, with a stronger oxygen transfer coefficient dependence in the conventional activated sludge compared to the membrane bioreactor. It was noted that the oxygen transfer coefficient in the conve…
Effect of biomass features on oxygen transfer in Conventional Activated Sludge and Membrane BioReactor systems
2018
The present study reports the results on the comparison between the oxygen transfer efficiency in a conventional activated sludge (CAS) and membrane bioreactor (MBR) system. The oxygen transfer was evaluated by means of the oxygen transfer coefficient (kLa)20 and α-factor calculation, under different operating conditions and with different activated sludge features, including total suspended solids (TSS) concentration, extracellular polymeric substances (EPS) content and composition, sludge viscosity and size of the flocs. The (kLa)20 and α-factor showed an exponential decreasing trends with TSS in the CAS and MBR, even if it was noted that the (kLa)20 dependence on TSS was stronger in the …
Free surface oxygen transfer in large aspect ratio unbaffled bio-reactors, with or without draft-tube
2015
Abstract It is widely accepted that animal cell damage in aerated bioreactors is mainly related to the bursting of bubbles at the air–liquid interface. A viable alternative to sparged bioreactors may be represented by uncovered unbaffled stirred tanks, which have been recently found to be able to provide sufficient mass transfer through the deep free surface vortex which takes place under agitation conditions. As a matter of fact, if the vortex is not allowed to reach impeller blades, no bubble formation and subsequent bursting at the free-surface, along with relevant cells damage, occurs. In this work oxygen transfer performance of large aspect ratio unbaffled stirred bioreactors, either e…