Rational design of packed saturators

1995 ◽  
Vol 31 (3-4) ◽  
pp. 179-190 ◽  
Author(s):  
Johannes Haarhoff ◽  
E. Maritz Rykaart
Keyword(s):  
Transfer Rate ◽  
Rational Design ◽  
Film Theory ◽  
Transfer Efficiency ◽  
Air Concentration ◽  
Dissolved Air Flotation ◽  
Mass Transfer Efficiency ◽  
Saturator Efficiency ◽  
Packing Size ◽  
Dissolved Air

The paper describes the development of a mathematical model for predicting the mass transfer efficiency of packed saturators used for dissolved air flotation. The first part of the paper deals with the equilibrium condition, i.e. the maximum attainable air concentration with a packed saturator at 100% transfer efficiency. The second part derives a kinetic model based on concentration-driven diffusion and the Lewis-Whitman two-film theory. The transfer rate constant across the laminar liquid film and the wetted packing area are estimated with the Onda correlations. The model is finally used to demonstrate the effects of hydraulic loading, packing depth, packing size and temperature on saturator efficiency.

Application of dissolved air flotation for treatment of wastewater from meat processing industry

1995 ◽  
Vol 31 (3-4) ◽  
pp. 341-344 ◽  
Author(s):  
J. Wasowski
Keyword(s):  
Rational Design ◽  
Meat Processing ◽  
Waste Waters ◽  
Processing Industry ◽  
Dissolved Air Flotation ◽  
Technological Factors ◽  
Air Flotation ◽  
The Given ◽  
Dissolved Air

The paper concerns the application of dissolved air flotation for treatment of waste water from the meat processing industry. The main aim of the study was identification of the flotation mechanism aided by the coagulation in the layouts with and without recycling, and finding and defining the role of the technological factors influencing flotability of pollutants found in the given waste waters. The results of the studies, supported by the mathematical analysis, form the basis of rational design and conduction of flotation in practice.

Characterization of micro-bubble size distribution and flow configuration in DAF contact zone by a non-intrusive image analysis system and tracer tests

2010 ◽  
Vol 61 (1) ◽  
pp. 253-262 ◽  
Author(s):  
R. B. Moruzzi ◽  
M. A. P. Reali
Keyword(s):  
Size Distribution ◽  
Contact Zone ◽  
Bubble Size ◽  
Bubble Size Distribution ◽  
Image Analysis System ◽  
Particle Removal ◽  
Air Concentration ◽  
Dissolved Air Flotation ◽  
Micro Bubble ◽  
Dissolved Air

This paper aims to investigate the influence of some dissolved air flotation (DAF) process variables (specifically: the hydraulic detention time in the contact zone and the supplied dissolved air concentration) and the pH values, as pretreatment chemical variables, on the micro-bubble size distribution (BSD) in a DAF contact zone. This work was carried out in a pilot plant where bubbles were measured by an appropriate non-intrusive image acquisition system. The results show that the obtained diameter ranges were in agreement with values reported in the literature (10–100 μm), quite independently of the investigated conditions. The linear average diameter varied from 20 to 30 μm, or equivalently, the Sauter (d3,2) diameter varied from 40 to 50 μm. In all investigated conditions, D50 was between 75% and 95%. The BSD might present different profile (with a bimodal curve trend), however, when analyzing the volumetric frequency distribution (in some cases with the appearance of peaks in diameters ranging from 90–100 μm). Regarding volumetric frequency analysis, all the investigated parameters can modify the BSD in DAF contact zone after the release point, thus potentially causing changes in DAF kinetics. This finding prompts further research in order to verify the effect of these BSD changes on solid particle removal efficiency by DAF.

Estimation of air concentration in dissolved air flotation (DAF) systems using a simple predictive tool

2013 ◽  
Vol 91 (1) ◽  
pp. 184-190 ◽  
Author(s):  
Alireza Bahadori ◽  
Gholamreza Zahedi ◽  
Sohrab Zendehboudi ◽  
Mohammad Bahadori
Keyword(s):  
Air Concentration ◽  
Predictive Tool ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

Behaviour of air injection nozzles in dissolved air flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 25-35 ◽  
Author(s):  
E. M. Rykaart ◽  
J. Haarhoff
Keyword(s):  
Bubble Coalescence ◽  
Second Phase ◽  
Initial Growth ◽  
Two Phase ◽  
Dissolved Air Flotation ◽  
Nozzle Orifice ◽  
Pressure Release ◽  
Air Volume ◽  
Air Flotation ◽  
Dissolved Air

A simple two-phase conceptual model is postulated to explain the initial growth of microbubbles after pressure release in dissolved air flotation. During the first phase bubbles merely expand from existing nucleation centres as air precipitates from solution, without bubble coalescence. This phase ends when all excess air is transferred to the gas phase. During the second phase, the total air volume remains the same, but bubbles continue to grow due to bubble coalescence. This model is used to explain the results from experiments where three different nozzle variations were tested, namely a nozzle with an impinging surface immediately outside the nozzle orifice, a nozzle with a bend in the nozzle channel, and a nozzle with a tapering outlet immediately outside the nozzle orifice. From these experiments, it is inferred that the first phase of bubble growth is completed at approximately 1.7 ms after the start of pressure release.

Enhanced rapid gravity filtration and dissolved air flotation for pre-treatment of river thames reservoir water

1998 ◽  
Vol 37 (2) ◽  
pp. 35-42 ◽  
Author(s):  
M. J. Bauer ◽  
R. Bayley ◽  
M. J. Chipps ◽  
A. Eades ◽  
R. J. Scriven ◽  
...  
Keyword(s):  
Water Treatment ◽  
Water Supply ◽  
21St Century ◽  
Reservoir Water ◽  
Dissolved Air Flotation ◽  
Lowland Rivers ◽  
Air Flotation ◽  
Pre Treatment ◽  
Counter Current ◽  
Dissolved Air

Thames Water treats approximately 2800Ml/d of water originating mainly from the lowland rivers Thames and Lee for supply to over 7.3million customers, principally in the cities of London and Oxford. This paper reviews aspects of Thames Water's research, design and operating experiences of treating algal rich reservoir stored lowland water. Areas covered include experiences of optimising reservoir management, uprating and upgrading of rapid gravity filtration (RGF), standard co-current dissolved air flotation (DAF) and counter-current dissolved air flotation/filtration (COCO-DAFF®) to counter operational problems caused by seasonal blooms of filter blocking algae such as Melosira spp., Aphanizomenon spp. and Anabaena spp. A major programme of uprating and modernisation (inclusion of Advanced Water Treatment: GAC and ozone) of the major works is in progress which, together with the Thames Tunnel Ring Main, will meet London's water supply needs into the 21st Century.

Fat recovery from dissolved air flotation sludge

2016 ◽  
Vol 2016 (9) ◽  
pp. 3543-3551
Author(s):  
H.W.H Menkveld ◽  
N. C Boelee ◽  
G.O.J Smith ◽  
S Christian
Keyword(s):  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

The study of intramolecular decay and intermolecular energy transfer for phosphorescent organic light-emitting devices

2021 ◽  
Vol 23 (12) ◽  
pp. 7495-7503
Author(s):  
Wanlin Cai ◽  
Kai Ren ◽  
Ancong Zhao ◽  
Xiulan Wu ◽  
Rongxing He ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Rational Design ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Intermolecular Energy ◽  
Intermolecular Energy Transfer ◽  
Organic Light Emitting Devices

Compared to the PtOO7-based system, the greater EQE of the PtON7-based system is mainly governed by the stronger energy transfer efficiency (ηEET); thus, it is necessary to evaluate ηEET from hosts to guests for the rational design of OLEDs.

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