The design and operation of conventional and novel flotation systems on a number of impounded water types

This paper describes the design of conventional Dissolved Air Flotation (DAF) systems, and the novel Counter Current Dissolved Air Flotation Filtration (COCODAFF®) process. The operation and performance of these plants on a variety of water types in the United Kingdom and South Africa is also described. The advantages of flotation processes for the treatment of impounded waters either high in colour, or with a high concentration of algae, is discussed. Other topics covered in this paper are hydraulic flocculation, and the application of Finite Element Analysis (FEA), to the design of flotation plants. It is concluded that the COCODAFF® process offers a number of advantages over conventional DAF systems.

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

Water Science & Technology ◽

10.2166/wst.1998.0098 ◽

1998 ◽

Vol 37 (2) ◽

pp. 35-42 ◽

Cited By ~ 5

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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Improvement of Operational Mode of Counter-Current Dissolved Air Flotation Process

2010 International Conference on Digital Manufacturing & Automation ◽

10.1109/icdma.2010.433 ◽

2010 ◽

Author(s):

Wang Yuheng ◽

Wang Qishan ◽

Zhuo Shengguang ◽

Li Na

Keyword(s):

Operational Mode ◽

Dissolved Air Flotation ◽

Flotation Process ◽

Air Flotation ◽

Counter Current ◽

Dissolved Air

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High concentration of ozone application by the DAF (Dissolved Air Flotation) system to treat livestock wastewater

Water Pollution VIII: Modelling, Monitoring and Management ◽

10.2495/wp060551 ◽

2006 ◽

Cited By ~ 2

Author(s):

B. H. Lee ◽

W. C. Song

Keyword(s):

High Concentration ◽

Livestock Wastewater ◽

Dissolved Air Flotation ◽

Air Flotation ◽

Dissolved Air

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Dissolved air flotation in Southern Africa

Water Science & Technology ◽

10.2166/wst.1995.0526 ◽

1995 ◽

Vol 31 (3-4) ◽

pp. 159-172 ◽

Cited By ~ 1

Author(s):

G. Offringa

Keyword(s):

Southern Africa ◽

Historical Development ◽

Industrial Effluents ◽

Water Reclamation ◽

Current Application ◽

Dissolved Air Flotation ◽

Air Flotation ◽

Sludge Thickening ◽

Counter Current ◽

Dissolved Air

A brief review is given of the historical development and current application of flotation technology in Southern Africa. Applications in water reclamation, sludge thickening, industrial effluents and water treatment are presented on the basis of some case studies and pilot investigations. Design philosophies followed are pointed out. Research and development performed and a few innovations by local engineers and scientists are highlighted. These include combination or integration of dissolved air flotation (DAF) with filtration, presettling and powdered activated carbon, a simple aeration nozzle, surface grids for float dewatering and stabilization, and a counter-current DAF.

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Counter-current dissolved air flotation/filtration

Water Science & Technology ◽

10.2166/wst.1995.0527 ◽

1995 ◽

Vol 31 (3-4) ◽

pp. 173-178 ◽

Cited By ~ 3

Author(s):

Andrew Eades ◽

W. J. Brignall

Keyword(s):

Water Treatment ◽

Pilot Plant ◽

Volume Flow Rate ◽

Scale Up ◽

Particulate Material ◽

Water Utilities ◽

Dissolved Air Flotation ◽

Air Flotation ◽

Counter Current ◽

Dissolved Air

Thames Water Utilities has developed and patented a Counter-current dissolved air flotation/filtration (COCO-DAFF) process as a compact water treatment system designed to remove particulate material from traditional water sources. In particular it has been developed to overcome operational problems with primary filters caused by seasonal blooms of filter blocking algae such as Melosira sp., Aphanizomenon sp. andAnabaena sp. The process can be run without flotation during periods when algae are not a problem, giving operational cost savings. This process differs from co-current dissolved air flotation in that the recycle water is introduced after the inlet structure, but above the filter media. This generates an even depth bubble blanket in the flotation tank through which all the flocculated water must pass. The advantages are that in moving the recycle inlet away from the flocculated water inlet the potential for floc damage by the recycle is eliminated. Also since the entire sludge blanket is supported by a deep, even, bubble blanket, on de-sludging any fall-out of sludge that occurs near the de-sludging weirs will have to go back down through the process, leading to subsequent re-floating, and a reduced potential for spiking of the floated turbidity. Process validation experiments have been carried out on a 1.4 Ml/d pilot plant based at the Kempton Advanced Water Treatment Centre, London. These tests have identified a required flocculation time of 15 minutes prior to counter-current flotation, and insensitivity to the depth of the air injection below top water level. Dissolved air distribution is achieved using a special high volume flow rate DAF nozzle designed to lower the number of nozzles required per unit area, and to maximise the spread of the bubble cloud for optimum bubble/particle contact. Computational fluid dynamics (CFD) has been used in the scale-up of the pilot plant experience into the first full scale of this design plant to be built, by PWT Projects, at the 200 Ml/d Walton AWTW, for Thames Water Utilities.

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