• 제목/요약/키워드: Dissolved Air Flotation

검색결과 92건 처리시간 0.025초

차세대 고효율 용존공기 부상공정(High Rate DAF)의 개발 (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)

  • Kiuru, H.J.
    • 상하수도학회지
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    • 제18권2호
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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.

슬러지의 성상이 DAF(Dissolved Air Flotation)를 이용한 팽화 슬러지 농축에 미치는 영향 (Effect of Sludge Characteristics on the Thickening of Bulking Sludge using DAF (Dissolved Air Flotation))

  • 김동석;박영식
    • 한국물환경학회지
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    • 제22권1호
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    • pp.97-103
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    • 2006
  • Excess sludge treatment and disposal currently represent a rising challenge for domestic or wastewater treatment plants due to economic, environmental and regulation factors. Conventional gravity sedimentation process has been widely used in sludge thickening. The operation method of the process is very simple, but the process requires long detention time for sludge thickening, uses polymers, and shows low sludge thickening efficiency. To solve the problems, we studied on DAF (Dissolved Air Flotation) system. We use bulking sludge of a paper manufacturing plant. The effects of parameters such as SVI (Sludge Volume Index), storage time, initial concentration and wet density of excess sludge were examined. The results showed that the more SVI was low, the more sludge was thickened. As storage time goes by, SVI was increased and thickening performance was deteriorated. In order to improve flotation performance at high concentration, high recycling ratio and pressure did not increase the concentration due to thickening limitation. The addition of 0.8 g/L of loess was increased flotation efficiency of 1.41 times.

DAF(Dissolved Air Flotation)를 이용한 제지폐수의 COD, SS 및 탁도 제거 (COD, SS and Turbidity Removal of Paper Wastewater Using DAE(Dissolved Air Flotation))

  • 김동석;박영식
    • 한국환경보건학회지
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    • 제31권4호
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    • pp.246-253
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    • 2005
  • The supernatant treatment of recovery process of raw materials of paper plant was studied using DAF (Dissolved Air Flotation) system. We investigated the removal efficiency (COD, SS and turbidity) of the DAF process. The effects of parameters such as A/S ratio, pressure, flotation conditions, coagulant concentration, mixing conditions, size and ratio of packing and nozzle type were examined. The results showed that the optimum A/S ratio and pressure were 0.058 and 4.5-5 atm, respectively. Injection times of pressurized water around 30 s and flotation times around 10 min appeared to be optimal for the DAF operation. Anion polymer addition improved the removal of COD, SS and turbidity. The smaller size and the more packing ratio were enhanced the removal efficiencies. The order of performance of nozzle was full cone > flat > assemble type.

DAF(Dissolved Air Flotation)를 이용한 팽화 슬러지 농축 (Thickening of Bulking Sludge using DAF (Dissolved Air Flotation))

  • 김동석;박영식
    • 한국환경과학회지
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    • 제15권1호
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    • pp.77-84
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    • 2006
  • An effective technique of sludge separation is required for excess sludge of sewage or wastewater plant. The separation of bulking sludge of paper manufacturing plant was studied using DAF(Dissolved Air Flotation) system. The effects of parameters such as nozzle type, A/S(air/solid) ratio. pressure, injection time of pressured water and saturation time were examined. The results showed that the best nozzle type was flat which had small orifice hole, The optimum A/S ratio and pressure were $7.070\times10^{-3}$(recycle ratio of pressured water $20\%$) and 5atm, respectively. Injection times of pressurized water around 20-25 sesc and flotation time of 30 min appeared to be optimal for the DAF operation. The order of performance of packing was 18 mm > 22 mm > 32 mm.

DAF(Dissolved Air Flotation)를 이용한 정수처리에서 처리조건에 따른 VOCs(Volatile Organic Compounds)의 처리효율에 대한 연구 (Removal Rates of VOCs(Volatile Organic Compounds) for Treatment Condition using DAF(Dissolved Air Flotation) in Water Treatment)

  • 김미정;전세진
    • 상하수도학회지
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    • 제13권3호
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    • pp.91-100
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    • 1999
  • Treatment conditions of DAF(Dissolved Air Flotation) and removal rates of VOCs(Volatile Organic Compounds) in mixed water of H raw water and VOCs were investigated. The used VOCs were benzene, toluene, ethylbenzene, and xylene in aromatic compounds and iso propyl mereaptan, n-butyl mereaptan, dimethyl disulfide, and iso butyl mercaptan in odors. The related parameters include water type, treatment method, clay concentration, pH condition, flocculation time, flotation time, per-cent recycle, water temperature, pressure. The removal rates of VOCs were different on treatment process and water condition. Treatment time was longer, removal rates of VOCs was higher. Water temperature was more important than pressure in DAF parameters. Molecular weight was related with removal rate in several kinds of VOCs were decraesed by competition of each component in II raw water. When algac blooming D water was treated by DAF, TCOD(Total chemical Oxygen Demand) and chorophyll a was removed over 96%.

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Coagulation and Flotation Conditions of Humic Acid by Dissolved Air Flotation

  • Lee, Chang-Han
    • 한국환경과학회지
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    • 제21권9호
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    • pp.1043-1051
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    • 2012
  • Coagulation, flocculation, and dissolved air flotation (DAF) experiments were performed with humic acid to evaluate the influence of operational conditions on removal efficiencies. We investigated coagulation, flocculation, and flotation conditions of humic acid removal using a laboratory-scale DAF system. This paper deals with coagulant type (aluminum sulfate and PSO-M) and the most relevant operational conditions (velocity gradients for coagulation and flocculation, retention time and recycle ratio and flotation time). Results showed that optimal conditions for removing humic acid, yielding CHA removal efficiencies of approximately 85 %, are a recycle ratio of 40 %, coagulant dosages of 0.15 - 0.20 gAl/gHA as aluminum sulfate and 0.03 - 0.12 gAl/gHA as PSO-M, coagulation($400s^{-1}$ and 60s), flocculation($60s^{-1}$ and 900s or more), and flotation(490 kPa or more and at least 10 min).

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

  • 김성진;강병준;박상욱;이재욱;정흥조;곽동희
    • 상하수도학회지
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    • 제20권4호
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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.

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

  • 곽동희;김성진;이화경;정흥조;이재욱;정팔진
    • 상하수도학회지
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    • 제16권6호
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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.

DAF 공정에서 공기포화장치와 노즐 특성 별 미세기포 발생에 미치는 영향 (An Effect of the Micro Bubble Formation Depending on the Saturator and the Nozzle in the Dissolved Air Flotation System)

  • 박상철;오호영;정몽규;송석용;안용희
    • 대한환경공학회지
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    • 제35권12호
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    • pp.929-936
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    • 2013
  • DAF (Dissolved air flotation) 공정에서 공기포화장치(Saturator)와 미세기포 발생노즐은 미세기포 형성에 중요한 영향을 미치는 장치이다. 미세기포 발생 효율을 증가시키기 위해서는 공기포화장치 용기 안에서 기-액 접촉 효율을 증가시키고, 미세기포 발생노즐까지 이송 배관 내 압력을 일정하게 유지해 주어야 한다. 본 연구에서는 공기포화장치 내 순환수 유입 분사노즐과 포화수 이송 배관, 미세기포 발생노즐에 의한 미세기포 발생에 미치는 영향을 공기체적법과 기포 크기, 기포의 잔류시간 측정을 통해 비교해 보았다. 순환수 유입 분사노즐을 설치하고, 포화수의 이송 배관 내 압력손실이 발생하지 않는 구조, 미세기포 발생노즐의 통과유속을 증가시킬 경우 미세기포 발생 성능이 증가하였다.

DAF 공정에서 부상속도 향상을 위한 플럭형성 조건 평가 (Evaluation of Floc Formation Conditions for Increasing Flotation Velocity in DAF Process)

  • 권순범;민진희;박노석;안효원
    • 상하수도학회지
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    • 제20권2호
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    • pp.245-255
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    • 2006
  • Dissolved air flotation is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In order to enhance the flotation velocity and removal efficiency of flocs in the flotation process, we tried to obtain pretreatment conditions for the optimum DAF process operation by comparing and evaluating features of actual floc formation and flotation velocity etc, according to coagulant types and conditions for flocculation mixing intensity by using PIA, PDA, and FSA. Accordingly, generating big flocs that have low density at low flocculation mixing intensity may reduce treatment efficiency. In addition, generating small flocs at high flocculation mixing intensity makes floc-bubbles smaller, which reduces flotation velocity, In this study, it was found that high flocculation mixing intensity could not remove the remaining micro-particles after flocculation, which had negative effects on treated water quality, Therefore, in order to enhance treatment efficiency in a flotation process, flocculation mixing intensity around $50sec^{-1}$ is effective.