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.

Effect of pressure on bubble size in dissolved air flotation

2002 ◽  
Vol 2 (5-6) ◽  
pp. 41-46 ◽  
Author(s):  
M. Han ◽  
Y. Park ◽  
J. Lee ◽  
J. Shim
Keyword(s):  
Bubble Size ◽  
Critical Pressure ◽  
Theoretical Work ◽  
Particle Sizes ◽  
Water And Wastewater Treatment ◽  
Dissolved Air Flotation ◽  
Recent Theoretical Work ◽  
Water And Wastewater ◽  
Air Flotation ◽  
Dissolved Air

Although dissolved air flotation (DAF) has been successfully adopted for water and wastewater treatment, the fundamental characteristics of the process have not been fully investigated. According to recent theoretical work on DAF, bubble size is one of the most important factors that affect the efficiency of the process, with better removal efficiency when the sizes of both bubbles and particles are similar. In this study, a newly developed particle counter method (PCM) was introduced to measure particle sizes. To confirm its usefulness, the results were compared with those from image analysis. Then, using PCM, the size of bubbles in DAF was measured under various pressure conditions which are known to affect the bubble size the most (from 2 to 6 atmospheres). The bubble size decreased as the pressure increased up to a pressure of 3.5 atmospheres. Above this critical pressure, the bubble size did not decrease with further increases in pressure. According to these experimental results, it is not only costly, but also unnecessary, to maintain a pressure above 3.5 atmospheres if the goal is only to generate smaller bubbles.

Research on treating algae-polluted reservoir water by the process of pre-oxidation/dissolved air flotation/carbon sand filter

2018 ◽  
Vol 19 (3) ◽  
pp. 823-830 ◽  
Author(s):  
Yonglei Wang ◽  
Wenhao Wang ◽  
Ruibao Jia ◽  
Mei Li ◽  
Baozhen Liu ◽  
...  
Keyword(s):  
Removal Rate ◽  
Water Diversion ◽  
Reflux Ratio ◽  
Reservoir Water ◽  
Combined Process ◽  
Dissolved Air Flotation ◽  
Blue Green Algae ◽  
Operation Conditions ◽  
Air Flotation ◽  
Dissolved Air

Abstract As the water diversion reservoir showed high organic matter and high algae in summer, the potassium permanganate pre-oxidation/dissolved air flotation/carbon sand double filter process was developed. The test results show that the optimum operation conditions of the combined process were as follows: the dosage of KMnO4 was 0.3 mg/L, the dosage of polymeric aluminum ferric chloride (PAFC) was 3.0 mg/L (Al3+), the reflux ratio was 10%, and the dissolved gas pressure was 0.3 Mpa. Taking Ji'nan Queshan reservoir water algae pollution as the research object, the average removal rate of chlorophyll a, blue-green algae, turbidity, particle number and total organic carbon (TOC) reached 66.64%, 95.44%, 94.45%, 99.34% and 46.68%, respectively; the methylisoborneol (MIB) removal rate was 92.47%, the odor level decreased with process flow from raw water level 4 to effluent level 1.5, geosmin (GSM) dropped below the detection limit, and the total removal rate of trihalomethane formation potential (THMFP) was 33.56%. The effluent of the combined process meets the requirements of the Hygienic Standard for Drinking Water (GB5749-2006) after it is disinfected.

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.

Effects of floc and bubble size on the efficiency of the dissolved air flotation (DAF) process

2007 ◽  
Vol 56 (10) ◽  
pp. 109-115 ◽  
Author(s):  
Mooyoung Han ◽  
Tschung-il Kim ◽  
Jinho Kim
Keyword(s):  
Bubble Size ◽  
Saturation Pressure ◽  
Collision Efficiency ◽  
Water And Wastewater Treatment ◽  
Dissolved Air Flotation ◽  
Floc Size ◽  
Recycle Ratio ◽  
Air Flotation ◽  
The 1960S ◽  
Dissolved Air

Dissolved air flotation (DAF) is a method for removing particles from water using micro bubbles instead of settlement. The process has proved to be successful and, since the 1960s, accepted as an alternative to the conventional sedimentation process for water and wastewater treatment. However, limited research into the process, especially the fundamental characteristics of bubbles and particles, has been carried out. The single collector collision model is not capable of determining the effects of particular characteristics, such as the size and surface charge of bubbles and particles. Han has published a set of modeling results after calculating the collision efficiency between bubbles and particles by trajectory analysis. His major conclusion was that collision efficiency is maximum when the bubbles and particles are nearly the same size but have opposite charge. However, experimental verification of this conclusion has not been carried out yet. This paper describes a new method for measuring the size of particles and bubbles developed using computational image analysis. DAF efficiency is influenced by the effect of the recycle ratio on various average floc sizes. The larger the recycle ratio, the higher the DAF efficiency at the same pressure and particle size. The treatment efficiency is also affected by the saturation pressure, because the bubble size and bubble volume concentration are controlled by the pressure. The highest efficiency is obtained when the floc size is larger than the bubble size. These results, namely that the highest collision efficiency occurs when the particles and bubbles are about the same size, are more in accordance with the trajectory model than with the white water collector model, which implies that the larger the particles, the higher is the collision efficiency.

Removal of cadmium from dilute solutions by flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 315-326 ◽  
Author(s):  
Anastasios I. Zouboulis ◽  
Konstantine A. Matis
Keyword(s):  
Sodium Dodecyl ◽  
Toxic Metal ◽  
Dilute Solutions ◽  
Water And Wastewater Treatment ◽  
Dissolved Air Flotation ◽  
Bubble Generation ◽  
Flotation Technique ◽  
Air Flotation ◽  
Ph Range ◽  
Dissolved Air

Cadmium constitutes a priority pollutant existing in waste streams from metal plating and various other industries. The removal of this toxic metal employing the dissolved air flotation technique was investigated in laboratory batch experiments; the mechanism of precipitate flotation as the respective hydroxide was followed. Main examined parameters include: recycle ratio, pH of the solution, concentrations of added surfactant (sodium dodecyl sulphate), frother (ethanol) and cadmium. Promising results have been obtained, at the pH range between 10 and 11 approximately, showing the significance of flotation as a separation process in water and wastewater treatment for dilute solutions (around 10 mg/l of metal). Under the optimum conditions removal of cadmium was near to 100%, while the remaining concentration in the solution after flotation was less than 0.10 mg/l. A comparison was also attempted between two flotation techniques applying different bubble generation methods, i.e. dissolved air and dispersed air flotation. These experiments run in parallel and under the same conditions.

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.

scholarly journals Changes in the Lower Drava River Water Quality Parameters Over 24 Years

2011 ◽  
Vol 62 (4) ◽  
pp. 325-333 ◽  
Author(s):  
Vlatka Gvozdić ◽  
Josip Brana ◽  
Dinko Puntarić ◽  
Domagoj Vidosavljević ◽  
Danijela Roland
Keyword(s):  
Water Quality ◽  
River Water ◽  
Heterotrophic Bacteria ◽  
Organic Pollution ◽  
Quality Parameters ◽  
River Water Quality ◽  
Water Quality Parameters ◽  
Drava River ◽  
High Concentrations ◽  
Post War

Changes in the Lower Drava River Water Quality Parameters Over 24 YearsThe goal of this study was to analyse 13 physico-chemical and microbiological parameters of the Drava River water at three sampling sites in the lower Drava region (eastern Croatia) over two distinct periods: the pre-war period between 1985 and 1992 and the post-war period between 1993 and 2008. Over both periods, most parameters kept within the tolerable water quality limits, while NO3-N, NH4-N and BOD5 were higher. The lower Drava showed slight organic pollution with high concentrations of dissolved oxygen. High levels of total coliforms and heterotrophic bacteria in the post-war period were only found downstream of the town of Osijek. Upstream of Osijek, the river showed a tendency for improvement.

scholarly journals Bio-Delipidation of Dissolved Air Flotation Pre-Treated Poultry Slaughterhouse Wastewater

2018 ◽  
Author(s):  
Siyasanga Mbulawa ◽  
Seteno Karabo Obed Ntwampe ◽  
Moses Basitere ◽  
Yolanda Mpentshu ◽  
Cynthia Dlangamandla ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Oxygen Demand ◽  
Industrial Applications ◽  
Quality Parameters ◽  
Bacterial Strains ◽  
Oil And Grease ◽  
Dissolved Air Flotation ◽  
Slaughterhouse Wastewater ◽  
Air Flotation ◽  
Dissolved Air

Delipidation is a method of defatting that is generally associated with the removal of residual lipids or lipid groups from matrices in which they are present in minute quantities. The bio-delipidation of protein-rich poultry slaughterhouse wastewater (PSW) pre-treated with a dissolved air flotation (DAF) system was developed using microbial lipases from bacterial strains isolated from the PSW. The efficacy of the bio-delipidation system was quantitatively characterised by comparing the quality parameters i.e., fats, oil and grease (FOGs), turbidity, total suspended solutes (TSS), total chemical oxygen demand (tCOD) and protein concentration of the DAF pre-treated PSW and bio-lipidized samples. As hypothesised, the bio-delipidation system was able to effectively reduce the levels of these quality parameters when crude lipases of Bacillus cereus AB1 (BF3) and Bacillus cereus CC-1 (B30) strains were used. Strain-dependent quality characteristics were also observed in bio-delipidized samples. The study successfully managed to complement physical reduction techniques (DAF) with biological strategies (bio-delipidation) for improved PSW quality, with potential industrial applications.

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