• Title/Summary/Keyword: 용존공기부상

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Flotation Separation of Biological Floc Using the Dissolved Air Flotation Process (용존공기부상(DAF) 공정을 이용한 생물학적 플록의 부상분리)

  • Kwak, Dong-Heui;Kim, Seong-Jin;Lim, Young-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.5
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    • pp.649-655
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    • 2004
  • The behavior of biological particles in DAF (dissolved air flotation) process was analyzed by employing PBT (Population balance theory). After decline growth phase of activated sludge, the value of the initial collision-attachment efficiency was increased over than 0.35 corresponding relatively high value in the whole life cycle of microorganism. For practical application of DAF as a solid separation process. It is desirable that microbial particles should be operated to perform high solid removal efficiency in biological wastewater treatment.

Operation Conditions for Continuous DAF Process with Domestic DAF Pump (국산 DAF 펌프가 적용된 연속 DAF 공정의 운전 조건)

  • An, Dae Myung;Lee, Chang Han;Ahn, Kab Hwan;Cho, Seok Ho;Kim, Seong-Soo
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.2
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    • pp.242-246
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    • 2004
  • Dissolved air flotation (DAF) is an effective solid/liquid separation process for low density particles, such as algal flocs, humus materials and clay particles produced from low turbidity water. The fraction of humic substances for natural organic matters (NOMs) are considered problematic in water because it can readily react with chlorine to form harmful by-products (trihalomethanes) and can be exposed to undesirable color, tastes and odors in drinking water. A broad class of NOMs includes fulvic acid, humic acid and humin. This paper will discuss the results from a study that performed with a DAF pump process using synthetic wastewater contained humic substance. Batch jar tests were performed to evaluate coagulant dose and recycle ratio on flotation efficiency.

Hydrodynamic Collision Efficiency and Flotation Characteristics of Inorganic Particles in DAF Process (DAF 공정에서 무기 고형입자의 유체역학적 충돌효율과 부상특성)

  • Kwak, Dong-Heui;Kim, Sung-Jin;Lee, Hwa-Kyung;Jung, Heung-Joe;Lee, Jae-Wook;Chung, Paul-Gene
    • Journal of Korean Society of Water and Wastewater
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    • v.16 no.6
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    • pp.655-662
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    • 2002
  • Separation characteristics of inorganic particles occurred during heavy rainwater were investigated in DAF (dissolved air flotation) process. In order to remove the inorganic particles effectively, the collision and flotation efficiencies were examined from a hydrodynamic point of view. Generally, the collision efficiency increased with floc size under the variation of fluid dynamic conditions including inertial force. However, more precise model should be required to analysis the collision efficiency expressed both the physical properties for inorganic particles and hydrodynamic conditions for a reactor.

Effect of Oyster Shell Addition on the Dissolved Air Flotation and Sedimentation of Bulking Sludge (팽화슬러지의 용존공기부상과 침전에 미치는 굴패각 첨가의 영향)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.1
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    • pp.82-88
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    • 2007
  • The objective of this study is to examine the effect of the waste oyster shell powder as the addition agent in bulking sludge thickening of paper manufacturing plant using DAF(Dissolved Air Flotation) and gravitational sedimentation. The effect of parameters such as dosage and size distribution of oyster shell were examined. The results showed that the optimum dosage of mixed oyster shell(size range : $\sim250{\mu}m$) was 0.8 g/L. The oyster shell addition of 5.0 g/L in sedimentation process was increased thickening concentration of 3.25 times. When 5.0 g/L of oyster shell was added in DAF process, water content of sludge was decreased from 95.5% to 82.7% in dewatering process using Buchner funnel test device. When size of oyster shell was divided four ranges($\sim53{\mu}m$, $53\sim106{\mu}m$, $106\sim150{\mu}m$, $150\sim250{\mu}m$), optimum size range for the flotation and dewatering was $53\sim106{\mu}m$.

Pretreatment Condition in the Full Scale Dissolved Air Flotation Process Using a DAF Pump (DAF 펌프를 이용한 실규모 용존공기부상 공정의 전처리 조건)

  • Lee, Chang-Han;An, Dae-Myung;Kim, Seong-Soo;Cho, Seok-Ho;Ahn, Kab-Hwan
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.1
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    • pp.58-63
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    • 2009
  • Dissolved air flotation (DAF) process is generally considered more effective than sedimentation process in raw water containing algae, humus materials, and low density particles. This study presents the treatment efficiencies by the coagulation and flocculation conditions at a drinking water treatment plant using a laboratory tester and the full scale DAF pump system. The full scale DAF pump system (F-DAF) in this study had a capacity of 5,000 $m^3$/d and a hydraulic surface loading of 10 m/hr. F-DAF in D drinking water treatment plant was continuously operated to determine the operational performance and pretreatment (mixing and coagulation) conditions. Results in the laboratory experiment showed that the optimum coagulant (PSO-M) doses required to 2.7~4.5 mL/$m^3$/NTU with raw water turbidity from 13.8 NTU to 56.3 NTU. F-DAF in the optimum coagulant dosage could be operated in effluent turbidity of 1 NTU or below for a month.

Effect of Zeta Potential of Clay and Algae Particles on Flotation Efficiency (점토와 조류입자의 제타전위가 부상분리 효율에 미치는 영향)

  • Choi, Do-Young;Kim, Seong-Jin;Jung, Heung-Jo;Lee, Se-Ill;Paik, Do-Hyeon;Lee, Jae-Wook;Kwak, Dong-Heui
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.4
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    • pp.437-445
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    • 2005
  • Zeta potential is a key parameter of double layer repulsion for individual particles and can usually be used to interpret the trend of coagulation efficiency. This study focused on the measurement of zeta potential of algae and clay under various experimental conditions including water characteristics (pure water, stream water, reservoir water) and coagulant dose (10~50 mg/L). Results showed that the variation of zeta potential was highly sensitive depending on the water characteristics and coagulation conditions. Zeta potential of two genera of algae (anabaena sp. and microcystis sp.) were changed highly with coagulant dosage, especially. On the basis of trajectory analysis, bubble-floc collision efficiency simulated in terms of zeta potential was fitted well with removal efficiency of chlorophyll-a from algae particles. It was found that the control of zeta potential was important for effective removal of algae particles.

Temperature Effect in the process of DAF as pretreatment of SWRO (해수담수화 전처리로서 DAF공정에서 고온의 해수에 대한 영향 특성)

  • Park, Hyunjin;Dockko, Seok
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.6
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    • pp.807-813
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    • 2012
  • Flocculation and flotation are used as pretreatment steps prior to the reverse osmosis (RO) process. During seawater treatment, high temperature can change the water chemistry of seawater during the process of coagulation. It also affects bubble volume concentration (BVC) and bubble characteristics. Coagulants such as alum and ferric salts at $40^{\circ}C$ can also change flux rates in the seawater reverse osmosis (SWRO) process. In this study, the bubble characteristics in dissolved air flotation (DAF), used as a SWRO pretreatment process, were studied in synthetic seawater at $20^{\circ}C$ and $40^{\circ}C$. The flux of an RO membrane was monitored after dosing the synthetic seawater with coagulants at different temperatures. Results showed that BVC increases as the operating pressure increases and as the salt concentration decreases. The bubble size released at $40^{\circ}C$ is far smaller than that at $20^{\circ}C$The addition of a ferric salt is effective for turbidity removal in synthetic seawater at $20^{\circ}C$; it is more effective than alum. When synthetic seawater was dosed with a ferric salt, the RO membrane flux increased by 27 % at $40^{\circ}C$.