Dissolved air flotation in potable water treatment: The Dutch experience

1995 ◽  
Vol 31 (3-4) ◽  
Keyword(s):  
Water Treatment ◽  
Potable Water ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dutch Experience ◽  
Potable Water Treatment ◽  
Dissolved Air

Dissolved air flotation in drinking water production

2001 ◽  
Vol 43 (8) ◽  
pp. 9-18 ◽  
Author(s):  
T. Schofield
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Potable Water ◽  
Water Production ◽  
Process Technology ◽  
Dissolved Air Flotation ◽  
Drinking Water Production ◽  
Air Flotation ◽  
Potable Water Treatment ◽  
Dissolved Air

Dissolved Air Flotation (DAF) has become increasingly important in the field of potable water treatment, as a preferred option for treating upland and stored lowland waters. This paper outlines the development of dissolved air flotation (DAF) in potable water treatment, the benefits and disadvantages and the recent advances that has taken the process technology from an art to a science.

scholarly journals The evaluation of polymeric organic coagulants for potable water treatment by dissolved air flotation

2001 ◽  
Author(s):  
◽  
Rachigan Rajagopaul
Keyword(s):  
Water Treatment ◽  
Ferric Chloride ◽  
Potable Water ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Potable Water Treatment ◽  
Dissolved Air

Historically inorganic coagulants were the coagulants of choice for OAF treatment of potable water. Water treatment practitioners using OAF technology preferred ferric chloride, an inorganic coagulant. Ferric chloride formed light, floatable floes at relatively low flocculation intensities and detention times. The inorganic coagulant was also more forgiving during incidents of overdosing and raw water and pH variability

Recent applications of dissolved air flotation pilot studies and full scale design

1995 ◽  
Vol 31 (3-4) ◽  
pp. 327-340
Author(s):  
Steven R. Arnold ◽  
Thomas P. Grubb ◽  
Peter J. Harvey
Keyword(s):  
Water Treatment ◽  
Potable Water ◽  
The United States ◽  
Wastewater Sludge ◽  
Design Parameters ◽  
Dissolved Air Flotation ◽  
Pilot Studies ◽  
Air Flotation ◽  
Potable Water Treatment ◽  
Dissolved Air

The use of Dissolved Air Flotation (DAF) as a solids/liquid separation process in water treatment has been an effective alternative to sedimentation for 70 years. The process was initially applied for removal of materials which had a specific gravity less than water, such as fats, oils, fibers, and grease. DAF installations expanded in the late 1960s to wastewater and potable water treatment. Today, Dissolved Air Flotation is utilized for a wide variety of water and wastewater applications. DAF is applied extensively for wastewater sludge thickening and it is widely accepted in Scandinavia and the United Kingdom for potable water treatment. It has also gained a foothold in the United States with the start up of a 7.5 mgd (28.4 Ml/d) potable water flotation plant at New Castle, New York. The goal of this paper is to present recent applications of Dissolved Air Flotation technology on a variety of raw water sources. Descriptions and general design parameters of a typical flotation and a proprietary combined flotation and filtration process will be discussed.

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.

Cryptosporidium removal during water treatment using dissolved air flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 125-135 ◽  
Author(s):  
T. Hall ◽  
J. Pressdee ◽  
R. Gregory ◽  
K. Murray
Keyword(s):  
Water Treatment ◽  
Metal Ion ◽  
Ion Concentration ◽  
Sudden Increase ◽  
Water Turbidity ◽  
Dissolved Air Flotation ◽  
Treatment Processes ◽  
Air Flotation ◽  
The Uk ◽  
Dissolved Air

The occurrence of the protozoan parasite Cryptosporidium parvum in water supplies, and the resultant outbreaks of cryptosporidiosis in the UK and USA, have led to concern over the ability of conventional water treatment processes to remove Cryptosporidia from water sources. Large scale pilot plant trials of water treatment have been carried out in the UK to establish the degree of removal that can be achieved by a range of treatment processes, including dissolved air flotation, and to compare the performance of different treatment options. Results from part of these trials are presented in this paper. These results suggest that well operated chemical coagulation based treatment, using either dissolved air flotation or floc blanket clarification, should be capable of achieving removal of Cryptosporidium oocysts of over 99%. There was no evidence of differences in performance between the different types of filter media investigated. The risk of increased Cryptosporidium concentration in the filtered water will increase as filtrate turbidity increases. However, other factors such as high coagulant metal-ion concentration in the filtered water, or a sudden increase in clarified water turbidity, without any increase in filtered water turbidity, may also indicate treatment problems and associated risk from Cryptosporidia. Recycling of backwash waters may also increase the risk.

Dissolved air flotation model for drinking water treatment

2000 ◽  
Vol 27 (2) ◽  
pp. 373-382 ◽  
Author(s):  
Ayman R Shawwa ◽  
Daniel W Smith
Keyword(s):  
Water Treatment ◽  
Kinetic Model ◽  
Contact Zone ◽  
Removal Rate ◽  
Particle Removal ◽  
Dissolved Air Flotation ◽  
First Order ◽  
Air Flotation ◽  
Particle Attachment ◽  
Dissolved Air

In this study, a kinetic model that describes bubble-particle transport and attachment in the contact zone of dissolved air flotation (DAF) process is presented. The kinetic model, which is based on the assumption that the contact zone is analogous to a chemical reactor, describes the particle removal rate as a first-order reaction with respect to the concentration of particles. It identified important parameters, such as the bubble-particle attachment efficiency (αPB). The theoretical first-order particle removal rate constant (kP), based on the mathematical model, was determined by varying αPB from 0.1 to 1.0. On the other hand, the experimental kP value was determined by measuring the mean residence time, the degree of mixing of particles, and the particle removal efficiency of the contact zone by conducting pilot-scale DAF experiments at different hydraulic loading rates and recycle ratios. The experimentally determined first-order particle removal rate constant was equal to the theoretical kP value when the bubble-particle attachment efficiency (αPB) was in the range of 0.35 to 0.55, which is considered typical for water treatment applications. The kinetic model can be used to predict DAF removal efficiencies provided that αPB is determined for the system under investigation and that the operating conditions applied in this research are used. However, independent experiments are required to verify the applicability of the proposed model.Key words: algae, bubble, coagulation, dissolved air flotation, flocculation, kinetic model, particle size distribution, water treatment.

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