• Title/Summary/Keyword: 용존공기부상

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Development of Dissolved Air Flotation Technology from 1st Generation to the Newest or 3rd One (Very Thick Microbubble Bed) with High Flowrates DAF in Turbulent Flow Conditions (차세대 고효율 용존공기 부상공정(High Rate DAF)의 개발)

  • Kiuru, H.J.
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.2
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    • pp.228-234
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    • 2004
  • Dissolved air flotation (DAF), in which suspended solids are removed from water by means of micro-size air bubbles raising slowly up in water and lifting solids from water (smaller than those) attached onto the micro-bubbles as well as those (larger than solids) being attached on these, have been used in water and wastewater since 1920s. The dissolved air flotation technology was originally based on the laminar flow conditions prevailing in water to be treated, but the latest development in that technology has led now to a situation, in which the flow conditions may also be turbulent ones in the modem dissolved air flotation units. Despite of that, the flotation phenomenon used in this unit operation for removal suspended solids from water or wastewater is still the same.

Water Treatment Using DAF(Disssolved Air Flotation) (용존공기 부상법(Disssolved Air Flotation)을 이용한 정수처리)

  • Lee, Byoung-Ho;Kim, Jae Hoon
    • Journal of Korean Society of Water and Wastewater
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    • v.10 no.2
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    • pp.80-87
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    • 1996
  • Treatment efficiencies of water quality parameters such as $KMnO_4$ Demand, $UV_{254}$, Turbidity, and LAS(Linear Alkyl Sulfonate) were compared between DAF(Dissolved Air Flotation) and CGS(Conventional Gravitational Sedimentation). The experimental results showed that DAF is much more efficient in treatment of water quality parameters than CGS. The optimum pH was about 7, and optimum alum($Al_2(SO_4)_3$) dose was about 30 ppm for DAF treatment. Economic aspects were also analyzed for bath systems. Even though production cost per ton of drinking water is slightly higher in DAF than in CGS, it turned out that construction cost and land value of CGS far surpass the production cost. DAF system is superior in removal efficiency of impurities and in production cost as a whole to CGS system.

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Flotation Characteristics of Activated Sludge by Micro-bubbles (미세 기포에 의한 활성슬러지의 부상특성)

  • Kim, Seong-Jin;Kang, Byoung-Jun;Park, Sang-Wook;Lee, Jae-Wook;Jung, Heung-Joe;Kwak, Dong-Heui
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.4
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    • pp.501-507
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    • 2006
  • Dissolved air flotation (DAF) has been well known for the gravity separation process. The solids to be separated are transferred from the water body to the water surface using micro-air bubbles. DAF has also been used for enhancing solids-liquid separation of industrial and municipal wastewater by adding a its unit parallel to a sedimentation unit to reduce the hydraulic loading in the sedimentation clarifier. This study was to investigate flotation characteristics of activated sludge by the recent DAF technique without chemical agents. In addition, the effect on temperature in flotation of activated sludge and the thickening degree of activated sludge were studied.

The Study of DAF-System to Apply the CSOs Treatment (CSOs의 오염물질 제거시 DAF-system의 적용에 관한 연구)

  • Lee, Tae-Gwan
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.3
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    • pp.385-391
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    • 2004
  • This paper examines the applicability of DAF-system to the domestic sewers for the effective CSOs treatment. The procedures for the experiment include mainly two steps. One is to analyse the water qualities and settling test of the CSOs and the other focuses on general characteristics of the CSOs such as the removal efficiency of pollutant, the distribution of particle size and mass balance of DAF-system. The result of this study show that the application of DAF-system is more effective and economical than the existing treatment systems because it has two removal mechanisms of sedimentation and flotation simultaneously.

A pilot study of high flux membrane process for responding to influent turbidity changes in reservoir water (호소수 탁도변화 대응을 위한 고플럭스 막여과공정의 Pilot 연구)

  • Kang, Joonseok;Seong, Jayeong;Yoo, Jewan;Kim, Hyungsoo;Lee, Jaekyu;Jeon, Minhyuk;Cheon, Jihoon
    • Journal of Korean Society of Water and Wastewater
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    • v.34 no.6
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    • pp.393-402
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    • 2020
  • In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.

A study on dissolved air flotation (DAF) process control using decision algorithm (의사결정 알고리즘을 이용한 DAF 공정 제어에 관한 연구)

  • Jung, Woosik;An, Ju-Suk;Park, Ji-Young;Oh, Hyun-Je
    • Journal of Korean Society of Water and Wastewater
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    • v.31 no.5
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    • pp.409-414
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    • 2017
  • In this study, we divided the process operation scenarios into three categories based on raw water temperature and turbidity. We will select and operate the process operation scenario according to the characteristics of the raw water. The number of algae in the DAF treated water has been analyzed to be less than 100 cells/mL. These results indicated that the DAF process is effective in removing the algae. In addition, the scenario of the integrated management decision algorithm of the DAF process was developed. DAF pilot plants ($500m^3/day$) process has shown a constantly sound performance for the treatment of raw water, yielding a significantly low level of turbidity (DAF treated water, 0.21~1.56 NTU).

Operation evaluation of DAF pilot plant for water treatment process in Hoedong Reservoir (회동수원지의 정수처리 공정을 위한 DAF pilot plant 운영 성능평가)

  • Maeng, Minsoo;Shahi, Nirmal Kumar;Kim, Donghyeun;Shin, Gwyam;Dockko, Seok
    • Journal of Korean Society of Water and Wastewater
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    • v.34 no.6
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    • pp.463-471
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    • 2020
  • A 1,000 ㎥/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 ㎛ showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.

Simulation study of DAF flotation basin using CFD (전산유체해석기법을 이용한 용존공기부상공정의 유동해석)

  • Park, Byungsung;Woo, Sungwoo;Park, Sungwon;Min, Jinhee;Lee, Woonyoung;You, Sunam;Jun, Gabjin
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.2
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    • pp.261-272
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    • 2013
  • Algae boom (Red tide) in south coastal area of Korea has been appeared several times during a decade. If algae boom appears in the desalination plant, media filter and UF filter are clogged quickly, and the plant should be shutdown. In general, Algae can be removed from water by flotation better than by sedimentation, because of the low density of algal cell. The purpose of this study conducts the CFD simulation of DAF flotation basin to apply the design of the dissolved air flotation with ball filter in the Test Bed for SWRO desalination plant. In this study, Eulerian-Eulerian multiphase model was applied to simulate the behavior of air bubbles and seawater. Density difference model and gravity were used. But de-sludge process and mass transfer between air bubbles and seawater were ignored. Main parameter is hydraulic loading rate which is varied from 20 m/hr to 27.5 m/hr. Geometry of flotation basin were changed to improve the DAF performance. According to the result of this study, the increase of hydraulic loading rate causes that the flow in the separation basin is widely affected and the concentration of air is increased. The flow pattern in the contact zone of flotation basin is greatly affected by the location of nozzle header. When the nozzle header was installed not the bottom of the contact zone but the above, the opportunity of contact between influent and recycle flow was increased.

High Rate Dissolved Air Flotation (DAF) for the Removal of Algae Species (유입원수 조류제거를 위한 high rate DAF 최적화 연구)

  • Jung, Woosik;An, Ju-Suk;Song, Keun-Won;Oh, Hyun-Je
    • Journal of Korean Society of Water and Wastewater
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    • v.31 no.5
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    • pp.415-419
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    • 2017
  • In recent years there have been large increases in the hydraulic loading rates used to design dissolved air flotation (DAF) facilities for drinking water applications. High rate DAF processes are now available at loading rates of 20 to $40m^3/m^2{\cdot}h$. This research evaluated dissolved air flotation as a separation method for algae and organic compounds from water treatment plants. During the service period of 2016. 5. to 2017. 6., DAF pilot plants ($500m^3/day$) process has shown a constantly sound performance for the treatment of raw water, yielding a significantly low level of turbidity (DAF treated water, 0.21~1.56 NTU). As a result of analyzing the algae cell counts in the influent source, it was expressed at 100-120 cells/mL. In DAF treated water, the removal efficient of alge cell counts was found to be upto 90%. The stable turbidity and algae removal were confirmed by operating the high rate DAF process under the condition of the surface loading rate of $30m^3/m^2{\cdot}hr$.

Treatment of Oil Contaminated Groundwater Using DAF and Fenton Oxidation Process (DAF와 펜톤 산화 공정을 이용한 유류 오염 지하수 처리)

  • Lee, Chaeyoung
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.10
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    • pp.49-55
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    • 2010
  • The oil spill occurred frequently due to probably the increased consumption of oil as the energy source and the raw materials of various chemicals. For the treatment of oil contaminated groundwater, DAF(Dissolved Air Flotation) is being used but the removal efficiency is low. Therefore it is necessary to reduce the free phase oil, oil-in water type or water-in oil type emulsified oil, and soluble oil which are the main sources of contaminated groundwater. In this study, treatment of contaminated groundwater was performed using the Fenton oxidation process. The optimum conditions for the removal of THP(Total Petroleum Hydrocarbon) were 3 of pH, 25mM of $H_2O_2$ concentration and 25mM of $Fe^{2+}$ concentration. THP and COD(Chemical Oxygen Demand) concentrations decreased less than 1.5mg/L and 40.0mg/L in 7 minutes using DAF and Fenton oxidation process. However it is necessary to install the settling basin as the sludge concentration increased approximately 5 times.