A simplified method for assessing the saturation efficiency at full-scale dissolved air flotation plants

1998 ◽  
Vol 38 (6) ◽  
pp. 303-310 ◽  
Author(s):  
S. Steinbach ◽  
J. Haarhoff
Keyword(s):  
Full Scale ◽  
Dissolved Air Flotation ◽  
Atmospheric Air ◽  
Comprehensive Method ◽  
Simplified Method ◽  
Saturation Efficiency ◽  
Air Flotation ◽  
Saturation Systems ◽  
Measuring Unit ◽  
Dissolved Air

This paper proposes a simplified yet comprehensive method for measuring the efficiency of air saturation systems used in dissolved air flotation. It is based on a review of methods suggested by other researchers in this field, but several improvements to existing methods are made. A saturation air composition different than that of atmospheric air and incomplete precipitation in the measuring unit after pressure release are taken into consideration. The developed measurement and calculation procedure provide engineers and operators alike with an easy tool to assess the saturation efficiency of their system at full-scale DAF plants as well as at pilot and laboratory scale plants.

Large batch bench-scale dissolved air flotation system (LB-DAF) for drinking water treatability tests

2020 ◽  
Vol 6 (4) ◽  
pp. 1004-1017 ◽  
Author(s):  
Juan Pablo Gonzalez-Galvis ◽  
Roberto M. Narbaitz
Keyword(s):  
Drinking Water ◽  
River Water ◽  
Full Scale ◽  
Dissolved Air Flotation ◽  
Large Batch ◽  
Bench Scale ◽  
Air Flotation ◽  
Dissolved Air

A new bench-scale batch DAF system was developed, for the river water tested it yielded better predictions of full-scale DAF turbidity removals than a commercial DAF jar tester.

Separation characteristics in dissolved air flotation - pilot and full-scale demonstration

2003 ◽  
Vol 48 (3) ◽  
pp. 89-96
Author(s):  
M. Ljunggren ◽  
L. Jönsson
Keyword(s):  
Particle Size ◽  
Contact Zone ◽  
Separation Efficiency ◽  
Particle Separation ◽  
Full Scale ◽  
Particle Sizes ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Practical Implications ◽  
Dissolved Air

This study presents practical implications for particle separation in Dissolved Air Flotation (DAF). The objectives were to localise where particles are separated from the water phase and to determine what particles, in terms of size, are removed by the DAF-process. Both pilot- and full-scale plants were investigated. Particle sizes were analysed with a light-blocking particle counter and an optical borescope was used for visualisation of particle-bubble aggregates. It was found that particles are preferably separated upstream in the process, i.e. close to the contact zone. Furthermore, separation efficiency for particles increased with increasing particle size.

Study of 3D-Printed Pressure Release Nozzle for Microbubble Formation in Full-Scale Dissolved Air Flotation (DAF)

2020 ◽  
Vol 155 ◽  
pp. 108070
Author(s):  
Alireza Kouhestani ◽  
Ali Amani Tehrani ◽  
Hesam Parsaeian ◽  
Mohamad Hosein Nikfar ◽  
Alireza Bazargan ◽  
...  
Keyword(s):  
Full Scale ◽  
Dissolved Air Flotation ◽  
Pressure Release ◽  
3D Printed ◽  
Air Flotation ◽  
Dissolved Air

The Adsorption Behaviour of Cationic Polyelectrolytes in Dissolved Air Flotation

1982 ◽  
Vol 14 (6-7) ◽  
pp. 689-704 ◽  
Author(s):  
R Gehr ◽  
J G Henry
Keyword(s):  
Full Scale ◽  
Adsorption Behaviour ◽  
Dissolved Air Flotation ◽  
Molecular Weights ◽  
Batch Tests ◽  
Solids Concentration ◽  
Air Flotation ◽  
Full Scale Tests ◽  
Cationic Polyelectrolytes ◽  
Dissolved Air

This study examines the adsorption behaviour of polymers of various molecular weights (MW) in dissolved air flotation (DAF) systems. Batch and full scale DAF tests were done using activated sludge. Residual polymer was measured by a titri-metric method, and Zeta potential (ZP) measurements of the effluent were also made. Two highly charged cationic polyelectrolytes of different MW were used. In batch tests, the two polymers yielded similar performance in terms of effluent and float solids concentrations, but slightly less high MW polymer was needed to attain low effluent SS. In both cases, polymer residual was detectable only when polymer doses beyond that needed for lowest effluent SS were applied. Significant increases in float solids concentration also occurred only at the higher doses. Polymer adsorption followed the Langmuir isotherm behaviour. Higher MW polymer adsorbed in larger quantity, indicating that the polymer “monolayer” was not flat on the surface of the sludge particles. ZP reversal (to a positive value) occurred only when polymer residual was detected, not at the polymer dose required for lowest effluent SS. Results were confirmed with full scale tests. A model for polymer-induced flocculation is presented, suggesting that polymer attachment occurs by attraction of opposite charges, but that bridging of colloids occurs to cause incorporation in the float. It is indicated that the cationic condition in the float at excess polymer dose causes exclusion of water in favour of air bubbles, and hence a more concentrated float.

Water clarification with natural coagulants and dissolved air flotation

Waterlines ◽  
1986 ◽  
Vol 5 (2) ◽  
pp. 23-26 ◽  
Author(s):  
Folkard ◽  
Sutherland ◽  
Jahn
Keyword(s):  
Dissolved Air Flotation ◽  
Natural Coagulants ◽  
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.

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