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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A numerical analysis technique for optimisation of microbial reaction and sludge flow has been developed in this study. The technique is based on the 3D multiphase Navier-Stokes solver with turbulence models. In order to make numerical analyses of the total processes in wastewater treatment plants possible, four numerical models, the microbial reaction model, a sludge settling model, oxygen mass transfer model from coarse bubbles, and a model from fine bubbles, are added to the solver. All parameters included in those models are calibrated in accordance with experimental results, and good agreements between calculated results and experimental results are found. Finally, this study shows that the numerical technique can be used to optimise wastewater treatment plants with an example of the operational optimisation of an intermittent agitation in anoxic reactors by coarse bubbles. With a proper appreciation of its limit and advantages, the exploitation of the CFD efficiently leads us to the right direction even though it is not quantitatively perfect.
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PMID:Development and exploitation of a multipurpose CFD tool for optimisation of microbial reaction and sludge flow. 1660 22

Mechanically aerated lagoons (used for wastewater treatment in the pulp and paper industry) are typically very large (>500,000 m3) and have complex three-dimensional fluid flow patterns due to mechanical agitation, sludge accumulation, internal baffling, and confined inlet/outlet flow channels. RTD data is frequently used for evaluation of hydraulic performance, however, obtaining accurate data with traditional dye measurements is a difficult and time-consuming process. Moreover, the mixing impact of factors such as aerator positions, sludge accumulation, and internal baffles would require a significant and costly number of local field measurements. Recent applications of CFD to mechanically aerated lagoons have helped engineers to understand the complex flow interactions. This paper provides a practical method for the evaluation of the hydraulic performance of large mechanically aerated lagoons using CFD. A method, based on random-walk Lagrangian particle tracking, has been developed to significantly shorten the computational time needed to produce RTD curves for these lagoons. Comparison of the particle method with the more conventional scalar transport yields excellent results. These methods allow wastewater engineers to combine their existing knowledge and expertise with the established power of CFD. The results quantify the hydraulic impact of different inlet/outlet configurations, aerator configurations, influent flow rates, and bottom sludge profiles.
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PMID:RTD (residence time distribution) predictions in large mechanically aerated lagoons. 1759 Nov 93

As far as flocculation is concerned, the agglomeration of suspended particles into flocs is highly linked to the hydraulic behaviour of the agitation. The Turbomix is a special design of mixing tank; its design was developed to better control the flow during the flocculation stage. It enables a significant decrease in footprint of the process. The combination of the Turbomix and ballasted flocculation has been studied during pilot trials in terms of treatment efficiency. Its controlled hydraulic behaviour explains the efficiency of the process as proved by CFD investigation.
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PMID:A new design of flocculation tank: the Turbomix applied to weighted flocculation. 1805 52

The effect of low-speed agitation on the level of secretion and glycosylation patterns of the Von Willebrand factor in endothelial cells cultured in 6-cm Petri dishes located in a rotating platform was studied. In this simple system, complex and non-intuitive velocity fields arise. As revealed by simple calculations of tangential velocities and CFD analysis, flow behavior strongly varies as a function of radial distance and rotational velocity. We found significant differences in both secretion level and glycosylation extent and completeness, as a result of relatively small changes in rotational speed. Results obtained support the hypothesis that differences in hydrodynamic conditions may induce important changes in the secretion and assembly of glycoproteins in mammalian cell cultures.
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PMID:Hydrodynamic conditions induce changes in secretion level and glycosylation patterns of Von Willebrand factor (vWF) in endothelial cells. 2022 85