A decade of large scale experience in dissolved air flotation

2001 ◽  
Vol 43 (8) ◽  
pp. 27-34 ◽  
Author(s):  
S. Kempeneers ◽  
F. Van Menxel ◽  
L. Gille
Keyword(s):  
Water Quality ◽  
Large Scale ◽  
Mechanical Design ◽  
Operational Experience ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
The Past ◽  
Air Flotation ◽  
Entire Treatment ◽  
Dissolved Air

In April 1990 Antwerpse Waterwerken brought a new DAF-plant into operation at the production centre Notmeir-Walem. The flotation unit, which has a capacity of 200,000 m3/d, was integrated in one of the two existing treatment lines. Its main objective was to eliminate the important raw water quality fluctuations caused by increasing algal growths. During the past ten years several optimisation studies were carried out which resulted in a further simplification of operation and mechanical design. This paper will focus mainly on the integration of dissolved air flotation in the entire treatment line, the consequences on the dual layer filtration and the operational experience and information gathered during the past decade.

High-rate dissolved air flotation for water treatment

2001 ◽  
Vol 43 (8) ◽  
pp. 43-49 ◽  
Author(s):  
M. A. P. Raeli ◽  
M. Marchetto
Keyword(s):  
Reynolds Numbers ◽  
Pilot Scale ◽  
Water Velocity ◽  
High Rate ◽  
Raw Water ◽  
Parallel Plates ◽  
Dissolved Air Flotation ◽  
Removal Efficiencies ◽  
Air Flotation ◽  
Dissolved Air

This paper presents the results of an experimental investigation about the performance of a horizontal flow high-rate pilot scale Dissolved Air Flotation (HRDAF) unit containing inclined parallel plates for treating a coloured and low turbidity raw water. Experiments were performed with the DAF unit in order to verify the influence on flotation of : (i) the water velocity (Vh) between the plates, in the range 18 to 96.5 cm.min−1 with corresponding Reynolds numbers between 240 and 1060; (ii) the supplied air (S*) value ranging from 2.2 to 8.5 g of air/m3 of water ; (iii) the angle of the plates (60° or 70°). The best pilot plant operational condition was obtained applying only 4.0 g/m3 (S*) with Vh around 18 cm.min−1 for treatment of water coagulated with a Al2(SO4)3 dosage of 40 mg.l−1. In these conditions, the unit presented very good removal efficiencies of colour (90%, residual of 10 uC), turbidity (88%, residual of 0.8 NTU ) and TSS (94%, residual of 1.8 mg.l−1). Furthermore, the unit could operate at higher Vh values up to 76 cm.min−1 and still present good results. The DAF unit thus behaved as a high rate unit presenting good performance with low air requirement.

Treatment Spent Filter Backwash Water using Dissolved Air Flotation (DAF) in Isfahan WTP

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
Mohammad Hassan Mahmoodian ◽  
Mohammad Mehdi Amin ◽  
Mohammad Reza Shahmansouri ◽  
Mohammad Ghasemian
Keyword(s):  
Low Dose ◽  
Saturation Pressure ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Recycle Rate ◽  
Polyaluminium Chloride ◽  
Significant Concentration ◽  
Dissolved Air ◽  
Filter Backwash Water

Recovering spent filter backwash water is currently receiving a great deal of attention. EPA published the Filter Backwash-Recycling Rule (FBRR) in 2001. Recycle stream may contain significant concentration of pathogens, such as, cryptosporidium and Giardia. Dissolved Air Flotation (DAF) was investigated as a possible technology alternative to simple or advanced sedimentation technology. In this study with using a pilot of DAF effluent turbidities of >20NTU could be easily obtained, when raw water turbidities were in excess of 800 NTU. Chemical requirements were low with only a single low dose of polyaluminium chloride (PACl) required binding the floc particles to form a solids matrix suitable for flotation. The results showed that the efficiency of continuous flow DAF with using PACl as coagulant for removal of Turbidity, COD, HPC, SS and MPN were 97, 72, 75, 95 and 100 percent, respectively. The statistical analyses indicated that the optimum saturation pressure is 4-5 atm, during recycle rate of 20-25 percent. The removal efficiencies of turbidity and bacteria in coagulation with sedimentation were reported up to 70 and 65 percent, while in this study using DAF with coagulant PACl could remove turbidity, COD, SS and bacterial up to 97,72, 95 and, 72 percent respectively.

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

The treatment of algae-laden raw water with compact flofilter of dissolved air flotation and GAC deep bed filtration

2004 ◽  
Vol 4 (5-6) ◽  
pp. 35-41
Author(s):  
X. Zhang ◽  
S. Zhang ◽  
Y. Liu
Keyword(s):  
Conventional Treatment ◽  
Good Alternative ◽  
Raw Water ◽  
Deep Bed Filtration ◽  
Dissolved Air Flotation ◽  
Chl A ◽  
Air Flotation ◽  
Filtration Unit ◽  
Advanced Treatments ◽  
Dissolved Air

Compact flofilter of dissolved air flotation and GAC deep bed filtration is a good integrated procedure, having the following characteristics: flotation and filtration are integrated in one tank, the flotation unit is above the filtration unit, filtration is GAC deep bed, and conventional and advanced treatments are integrated in one tank. During the treatment of algae-laden raw water with compact flofilter of dissolved air flotation and GAC deep bed filtration, the general performance was good: the outlet algae-count was 1.21×105–1.26×106 cell/l, the average removal of algae was 95.4%, the outlet chl-a was 0.68 μg/l, the removal of chl-a was 92.2%, the outlet turbidity was 0.16–0.20 NTU, the outlet had no odor, the outlet color was 3, the removal of color was 86.4%, the outlet Al-residual was 0.011 mg/l. Good removal of organics can be achieved: the average removal of UV254 was 54.3%, the outlet UV254 was 0.016–0.018 cm−1, the removal of DOC was 29.6%, the outlet DOC was 1.608 mg/l, the removal of BDOC was 42.6%, the outlet BDOC was 0.120 mg/l, the removal of AOC was 72.2%, the outlet AOC was 52 μg/l. Filter run period and UFRV were 36 h and 504 m3/m2. The results show that flofilter is a good alternative process for conventional treatment plus GAC adsorption.

Pretreatment considerations for dissolved air flotation: water type, coagulants and flocculation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 63-71 ◽  
Author(s):  
Donald Q. Bunker ◽  
James K. Edzwald ◽  
Jan Dahlquist ◽  
Lars Gillberg
Keyword(s):  
Chemical Properties ◽  
Water Type ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
Mixing Intensity ◽  
Flotation Performance ◽  
Air Flotation ◽  
Favorable Conditions ◽  
Flocculation Time ◽  
Dissolved Air

Pretreatment considerations of coagulant selection, flocculation time and flocculation mixing intensity were studied for two different water supply types, aquatic humic and non-aquatic humic waters of low turbidity. Alum, ferric salts, and various polyaluminium chlorides (PACs) with different chemical properties were all effective in dissolved air flotation (DAF) when used under favorable conditions of dosage, pH, and flocculation time. A stoichiometry was found for the aluminium coagulants between coagulant dose and raw water DOC. Si and sulfate PACs were effective in treating cold waters with short flocculation times of 2.5 to 5 minutes. Flotation performance improved slightly with increasing flocculation mixing intensity. The results suggest that flocculation tanks be designed to produce strong, “pinpoint” size floc particles.

Comparative Study of Dissolved Air Flotation and Sedimentation Process for Treating Reservoir Water with Low Temperature, Low Turbidity and High Natural Organic Matter

2011 ◽  
Vol 71-78 ◽  
pp. 2767-2771 ◽  
Author(s):  
Jing Zou ◽  
Jun Tao Zhu ◽  
Chao Pan ◽  
Jun Ma
Keyword(s):  
Water Quality ◽  
Low Temperature ◽  
Bubble Column ◽  
Reservoir Water ◽  
Dissolved Air Flotation ◽  
Sedimentation Process ◽  
Air Flotation ◽  
Better Than ◽  
Glass Bubble ◽  
Dissolved Air

In this research, the dissolved air flotation (DAF) were tried to treat drinking water to replace traditional sedimentation technology. Experimental study of sedimentation process and DAF was carried out in a jet tester and a glass bubble column respectively. The experimental results demonstrated that the indicators of water quality such as turbidity, chromaticity and CODMn after two processes decreased firstly and then increased with the PAC-dose increasing, and 7.41 mg Al L-1 was the optimum PAC dosage. Moreover, with the optimum PAC dosage, water quality after DAF proved much better than that after sedimentation process. As a result, DAF is a more effective technology to treat the reservoir water with low temperature, low turbidity and high NOM.

Long-term Comparison Testing with Sand Ballasted Flocculation (SBF) and High-rate Dissolved Air Flotation (DAF).

2008 ◽  
Vol 3 (4) ◽  
Author(s):  
J. Van Cappellen ◽  
J. Clement ◽  
S. Kempeneers ◽  
G. Budd ◽  
W. Bossaerts ◽  
...  
Keyword(s):  
High Rate ◽  
Operational Experience ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Water Companies ◽  
Technology Comparison ◽  
Dissolved Air

This paper reports on the investigation conducted by Antwerp Water Works (AWW) in Belgium to make a long term (12 months) comparison between SBF and high-rate DAF to determine which process would be optimal. Three major objectives where put forward at the beginning of the study: technology comparison, gain operational experience and conduct coagulant testing. This paper discusses the result obtained with respect to these objectives. Overall this paper clearly points to the value this type of piloting can bring to water companies.

A case study of dissolved air flotation for seasonal high turbidity water in Korea

2004 ◽  
Vol 50 (12) ◽  
pp. 245-253 ◽  
Author(s):  
S.B. Kwon ◽  
H.W. Ahn ◽  
C.J. Ahn ◽  
C.K. Wang
Keyword(s):  
Operation Mode ◽  
Raw Water ◽  
Freshwater Algae ◽  
Water Turbidity ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Direct Filtration ◽  
Air Flotation ◽  
Full Scale Tests ◽  
Dissolved Air

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme.

Enhanced separation of water quality parameters in the DAF (Dissolved Air Flotation) system using ozone

2007 ◽  
Vol 56 (10) ◽  
pp. 149-155 ◽  
Author(s):  
Byoung-Ho Lee ◽  
Won-Chul Song ◽  
Hye-Young Kim ◽  
Jeong-Hyeon Kim
Keyword(s):  
Water Quality ◽  
Heterotrophic Bacteria ◽  
Removal Rate ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Water And Wastewater Treatment ◽  
Dissolved Air Flotation ◽  
Micro Bubble ◽  
Air Flotation ◽  
Dissolved Air

Dissolved Air Flotation (DAF) has been used in water and wastewater treatment because it has an excellent separation capability. It was found that the separation capability of the DAF system could be even more enhanced by ozone. Ozone was applied as a substitute for air in the DAF system, so that the system was named as the DOF (Dissolved Ozone Flotation) system. Ozone not only enhances coagulation as is well known, but also provides larger micro-bubble volume because the solubility of ozone in water is much higher than that of air. Ozone enhanced the separation rate of SS by 13.6%, and turbidity by 21% in the DOF system compared to the DAF system. T-P was also removed 7.7% more in the DOF system. 41.5% of color and 7.4% of CODCr were enhanced in their removal rate. Coliform and heterotrophic bacteria were removed 54% and 57.3% more in the DOF system. Separation capability of the DOF system was greatly enhanced for most of the water quality parameters because ozone provides strong oxidation power with large volume of micro-bubbles.

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