The removal efficiency and mechanism of microplastic enhancement by positive modification dissolved air flotation

2020 ◽  
Author(s):  
Yonglei Wang ◽  
Ya'nan Li ◽  
Liping Tian ◽  
Ling Ju ◽  
Yulei Liu
Keyword(s):  
Removal Efficiency ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

Effects of Al3 +  and hydraulic characteristics on the removal and behaviour of particles in dissolved air flotation

2006 ◽  
Vol 6 (3) ◽  
pp. 89-95
Author(s):  
Jungsoo Mun ◽  
Sungwon Park ◽  
Mooyoung Han
Keyword(s):  
Turbulent Flow ◽  
Removal Efficiency ◽  
Operating Conditions ◽  
Point Of Zero Charge ◽  
Hydraulic Characteristics ◽  
Dissolved Air Flotation ◽  
Floc Size ◽  
Saturated Water ◽  
Air Flotation ◽  
Dissolved Air

The removal efficiency of the dissolved air flotation (DAF) process to separate particles from water and wastewater depends on the size and zeta potential of bubbles and particles, the solution and operating conditions, hydraulic characteristics, etc. The effects of aluminium ions and turbulent flow-produced when air-saturated water was spouted into the reactor in the DAF process, on removal and, particle behaviour were on investigated. When bubble size was similar to particle size (10–50 μm), the maximum removal efficiency was 92% in a Kaolin solution of 10−3 M Al3 +  without pre-treatment for flocculation process, and, as time passed, the floc size was observed to increase at a pH of 8, which was the condition of high removal efficiency as seen through image analysis. When the air-saturated water was spouted into the reactor, the size of particle at p.z.c. (point of zero charge) seemed to increase to form a floc due to collision effects caused by turbulent flow. Consequently, floc formation by turbulent flow in the reactor seemed to positively affect removal efficiency.

Flow structures in a dissolved air flotation pilot tank and the influence on the separation of MBBR floc

2002 ◽  
Vol 2 (2) ◽  
pp. 69-76 ◽  
Author(s):  
M. Lundh ◽  
L. Jönsson ◽  
J. Dahlquist
Keyword(s):  
Flow Structure ◽  
Removal Efficiency ◽  
Pilot Plant ◽  
Suspended Solids ◽  
Short Circuit ◽  
Flow Structures ◽  
Dissolved Air Flotation ◽  
Air Content ◽  
Air Flotation ◽  
Dissolved Air

The objective of the study was to find ways of improvement of the dissolved air flotation process by studying the flow structure. The paper presents experimental data on flow structures and the relation between the flow structure and the removal efficiency. Measurements have been performed in a pilot plant with an Acoustical Doppler Velocimeter. The water velocity was measured in a grid net, giving insight into the flow structure. The removal efficiency was analysed at Malmö wastewater treatment plant in Sweden. The pilot plant separated biological floc from a Kaldnes Moving Bio-Bed Reactor (MBBR). The efficiency of the separation was analysed by measurements of suspended solids in the influent and the effluent. Air content was measured inside the tank and in the re-cycle. The result showed that basically two flow structures existed; the stratified and the short-circuit flow structure. The stratified flow structure seemed correlated to efficient separation of particles while the short-circuit flow structure seemed to have a negative effect, especially when the flow structure was affected by varying the re-cycle rate, i.e. the air content. Conclusively, the flow structure seemed to be correlated to type of flow structure. However, studies with higher concentration of suspended solids for verification were suggested.

Dissolved air flotation of polishing wastewater from semiconductor manufacturer

2006 ◽  
Vol 53 (7) ◽  
pp. 133-140 ◽  
Author(s):  
J.C. Liu ◽  
C.Y. Lien
Keyword(s):  
Removal Efficiency ◽  
Suspended Particle ◽  
Saturation Pressure ◽  
Silica Particles ◽  
Ammonium Bromide ◽  
Dissolved Air Flotation ◽  
Recycle Ratio ◽  
Semiconductor Manufacturer ◽  
Air Flotation ◽  
Dissolved Air

The feasibility of the dissolved air flotation (DAF) process in treating chemical mechanical polishing (CMP) wastewater was evaluated in this study. Wastewater from a local semiconductor manufacturer was sampled and characterised. Nano-sized silica (77.6 nm) with turbidity of 130±3 NTU was found in the slightly alkaline wastewater with traces of other pollutants. Experimental results indicated removal efficiency of particles, measured as suspended particle or turbidity, increased with increasing concentration of cationic collector cetyltrimethyl ammonium bromide (CTAB). When CTAB concentration was 30 mg/L, pH of 6.5±0.1 and recycle ratio of 30%, very effective removal of particles (> 98%) was observed in saturation pressure range of 4 to 6 kg/cm2, and the reaction proceeded faster under higher pressure. Similarly, the reaction was faster under the higher recycle ratio, while final removal efficiency improved slightly as the recycle ratio increased from 20 to 40%. An insignificant effect of pH on treatment efficiency was found as pH varied from 4.5 to 8.5. The presence of activator, Al3 +  and Fe3 + , enhanced the system performance. It is proposed that CTAB adsorbs on silica particles in polishing wastewater through electrostatic interaction and makes particles more hydrophobic. The increase in hydrophobicity results in more effective bubble-particle collisions. In addition, flocculation of silica particles through bridging effect of collector was found; it is believed that flocculation of particles also contributed to flotation. Better attachment between gas bubble and solid, higher buoyancy and higher air to solid ratio all lead to effective flotation.

Oil removal efficiency forecast of a Dissolved Air Flotation (DAF) reduced scale prototype using the dimensionless number of Damköhler

2018 ◽  
Vol 23 ◽  
pp. 45-49 ◽  
Author(s):  
Fernanda Cristina P. Rocha e Silva ◽  
Nathalia Maria P. Rocha e Silva ◽  
Ivison Amaro da Silva ◽  
Pedro P. Ferreira Brasileiro ◽  
Juliana M. Luna ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Dimensionless Number ◽  
Oil Removal ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Reduced Scale ◽  
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

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.

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