An integrated approach to dissolved air flotation

2001 ◽  
Vol 43 (8) ◽  
pp. 19-26 ◽  
Author(s):  
T. Amato ◽  
J. K. Edzwald ◽  
J. E. Tobiason ◽  
J. Dahlquist ◽  
T. Hedberg
Keyword(s):  
Product Quality ◽  
Integrated Approach ◽  
Dissolved Air Flotation ◽  
Loading Rates ◽  
Air Flotation ◽  
Dissolved Air

DAFRapide® techniques utilising reduced flocculation times, of the order of 5 minutes, together with flotation loading rates of up to 40 m/h, can be incorporated with conventional filtration systems operating at up to 20 m/h. Product quality of typically <1 NTU and <0.1 NTU after flotation and filtration respectively can be achieved.

Modelling the global efficiency of dissolved air flotation

2001 ◽  
Vol 43 (8) ◽  
pp. 159-166 ◽  
Author(s):  
D. M. Leppinen ◽  
S. B. Dalziel ◽  
P. F. Linden
Keyword(s):  
Particle Size ◽  
Bubble Size ◽  
High Surface ◽  
Surface Loading ◽  
Dissolved Air Flotation ◽  
Loading Rates ◽  
Air Flotation ◽  
Bubble Attachment ◽  
Attachment Process ◽  
Dissolved Air

The purpose of this paper is to examine how the efficiency of dissolved air flotation is affected by the size of bubbles and particles. The rise speed of bubble/particle agglomerates is modelled as a function of bubble and particle size, while the kinematics of the bubble attachment process is modelled using the population balance approach adopted by Matsui, Fukushi and Tambo. It is found that flotation, in general, is enhanced by the use of larger particles and larger bubbles. In particular, it is concluded that for the ultra-high surface loading rates of 25 m/hr or more planned for future flotation tanks, bubble size will have to be increased by a factor of two over the size currently employed in many facilities during dissolved air flotation.

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

A study on the feasibility and mechanism of enhanced co-coagulation dissolved air flotation with chitosan-modified microbubbles

2021 ◽  
Vol 40 ◽  
pp. 101847
Author(s):  
Yonglei Wang ◽  
Wentao Sun ◽  
Luming Ding ◽  
Wei Liu ◽  
Liping Tian ◽  
...  
Keyword(s):  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

Evaluation of flocculation and dissolved air flotation as an advanced wastewater treatment

2001 ◽  
Vol 43 (8) ◽  
pp. 83-90 ◽  
Author(s):  
A. C. Pinto Filho ◽  
C. C. Brandão
Keyword(s):  
Wastewater Treatment ◽  
Domestic Wastewater ◽  
High Rate ◽  
Advanced Treatment ◽  
Dissolved Air Flotation ◽  
Anaerobic Reactor ◽  
Treatment Processes ◽  
Domestic Wastewater Treatment ◽  
Air Flotation ◽  
Dissolved Air

A bench scale study was carried out in order to evaluate the applicability of dissolved air flotation (DAF) as an advanced treatment for effluents from three different domestic wastewater treatment processes, namely: (i) a tertiary activated sludge plant ; (ii) an upflow sludge blanket anaerobic reactor (UASB); and (iii) a high-rate stabilization pond.

Innovative use of dissolved air flotation with biosorption as primary treatment to approach energy neutrality in WWTPs

2015 ◽  
Vol 10 (1) ◽  
pp. 133-142 ◽  
Author(s):  
H.-B. Ding ◽  
M. Doyle ◽  
A. Erdogan ◽  
R. Wikramanayake ◽  
P. Gallagher
Keyword(s):  
Biogas Production ◽  
Primary Treatment ◽  
Anaerobic Sludge ◽  
Excess Sludge ◽  
Dissolved Air Flotation ◽  
Biogas Yield ◽  
Air Flotation ◽  
Sludge Thickening ◽  
Plant Capacity ◽  
Dissolved Air

This paper presents two types of dissolved air flotation application together with biosorption (the ‘Captivator® system’) as primary treatments. In the first instance, the Captivator® system is the sole primary treatment for a new plant installation and helps to gain 65% more biogas while requiring only 44% of aeration for COD oxidation, compared to a conventional process with a primary clarifier. In the second application, the Captivator® system is used to enhance the existing primary treatment for plant capacity expansion. With digested anaerobic sludge recycled as an additional adsorbent, the Captivator® system in the second application increases the biogas yield by 52% and only generates 59% excess sludge. Overall, the Captivator® system would help WWTPs to approach energy neutrality by diverting more organics for biogas production and reducing the energy requirements for aeration. In addition, it would help to reduce the installation footprint for primary treatment and save considerable capital cost by eliminating the sludge thickening process.

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