• Title/Summary/Keyword: DAF

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Solid Separation and Flotation Characteristics of Livestock Wastewater Using DAF Process (DAF 공정을 이용한 축산폐수의 고형물 분리와 부상특성)

  • Kang, Byong-Jun;Yoo, Seung-Joon;Lee, Se-il;Kwak, Dong-Heui
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.3
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    • pp.359-366
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    • 2008
  • The series of experiments under the various conditions were carried out to evaluate the feasibility of dissolved air flotation (DAF) as an alternative of conventional gravity sedimentation (CGS) and to investigate the decrease of the loadings following to biological wastewater treatment processes in livestock wastewater system. On the basis of the experiment result between CGS and DAF processes, for the other water quality criteria as well as suspended solid the removal efficiency of DAF process was about 20~25 % better than CGS process on average. In addition, the particle removal efficiency of DAF process became higher in proportion as the increase of air to solid (A/S) ratio and the general wastewater treatment efficiency of DAF process was enough to meet the requirement of loading decrease to following biological process even at low A/S ratio range. Though DAF process is widely known as an solid separation unit, there was not the notable relationship between particle separation efficiency and several pollutant removal efficiencies like $COD_{Cr}$ and nutrients (T-N, T-P). Assume that the $COD_{Cr}$ was removed as the fraction of particle separation in this experiment, the removal efficiency of T-N and T-P were sensitive to removal efficiency of $COD_{Cr}$, especially.

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.

The Study on Research Data Management of Researchers in the Field of Forestry Engineering using DAF(Data Asset Framework) - Focused on National Institute of Forest Science - (DAF(Data Asset Framework)를 활용한 임산공학 분야 연구자들의 연구데이터 관리 개선 방안 - 국립산림과학원을 중심으로 -)

  • Kim, Juseop;Han, Yeonjung;Youe, Won-Jae;Jeon, Yerin;Kim, Suntae
    • Journal of Korean Library and Information Science Society
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    • v.51 no.2
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    • pp.103-131
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    • 2020
  • This study was started with the aim of grasping the current status of research data management of forestry engineering researchers. In order to achieve the research purpose, the survey was conducted using a tool called DAF (Data Asset Framework). DAF is an investigative tool that provides a means to identify, position, describe and evaluate how the agency manages research data. Using this DAF, the research data management status was analyzed for researchers in the field of forestry engineering at the National Institute of Forest Science. As a result of analysis, the current status and problems of the five categories such as the method and type of research data creation, sharing, storage, preservation, and reuse were identified, and solutions were presented in relation to the problems. This study is a basic investigation using a systematic tool such as DAF, and can be used as a reference for analyzing the current status and problems of research data when designing RDM system in a specific field.

Diagonalized Approximate Factorization Method for 3D Incompressible Viscous Flows (대각행렬화된 근사 인수분해 기법을 이용한 3차원 비압축성 점성 흐름 해석)

  • Paik, Joongcheol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3B
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    • pp.293-303
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    • 2011
  • An efficient diagonalized approximate factorization algorithm (DAF) is developed for the solution of three-dimensional incompressible viscous flows. The pressure-based, artificial compressibility (AC) method is used for calculating steady incompressible Navier-Stokes equations. The AC form of the governing equations is discretized in space using a second-order-accurate finite volume method. The present DAF method is applied to derive a second-order accurate splitting of the discrete system of equations. The primary objective of this study is to investigate the computational efficiency of the present DAF method. The solutions of the DAF method are evaluated relative to those of well-known four-stage Runge-Kutta (RK4) method for fully developed and developing laminar flows in curved square ducts and a laminar flow in a cavity. While converged solutions obtained by DAF and RK4 methods on the same computational meshes are essentially identical because of employing the same discrete schemes in space, both algorithms shows significant discrepancy in the computing efficiency. The results reveal that the DAF method requires substantially at least two times less computational time than RK4 to solve all applied flow fields. The increase in computational efficiency of the DAF methods is achieved with no increase in computational resources and coding complexity.

The treatment of sewage using DAF pump system with micro bubble and non-powered flotation tank (응집제 자동혼합형 미세기포 발생장치와 무동력 부상분리조를 이용한 하수의 처리)

  • Kim, Dong-Ha;Lee, Soo-Young;Jung, Eui-Taek
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.5
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    • pp.659-666
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    • 2011
  • Although DAF(Dissolved Air Flotation) has been successfully accepted for water and wastewater treatment, the fundamental characteristics of the process have not been fully investigated. Water is saturated with compressed air to dissolve the air into the water at high pressure in saturation tank. Then the water containing dissolved air is released into a floatation tank at a lower pressure, generating micro-bubbles that rise gently through the water and carry the suspended matter to the surface. This study investigated the removal of sewage using automatic mixture type DAF pump and non-powered flotation tank. Characteristics of two devices were compared and analyzed with samples. The results showed that the PAC exhibited higher performance than other coagulants. When air dosage was 2.5ml/l/min, treatment was stable in operation. In the DAF pump with a pressure of 4 atm., the average size of bubbles was 36.2${\mu}m$. Removal efficiency of SS was 80%. At this time removal efficiency of COD was about 80%, of T-N was 30% and T-P was 70% in stable operation. It was concluded that DAF pump system with micro bubble performed higher efficiencies compared to general DAF system for treating wastewater.

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.

Comparison of Removal Rates of Sedimentation and DAF(Dissolved Air Flotation) for various Different Conditions in Water Treatment (정수처리공정의 침전법을 개선하기 위한 대체공정으로 용존공기부상법(DAF)을 사용할 때 여러조건에 대한 처리효율 비교)

  • Kim, Mi-Jeong;Lee, Byoung-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.11 no.4
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    • pp.118-125
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    • 1997
  • Conventional sedimentation method has some limitations for turbidity removal in water treatment because drinking water sources are getting polluted. Removal rates of turbidity using DAF and sedimentation process were compared for various water conditions to know whether DAF is effective to improve sedimentation process. Water samples were clay(gravity 2.65) water 100mg/l, H raw water, mixed water of H raw water and clay 100mg/l, and mixed water of HA(Humic Acid) 5mg/l and clay 100mg/l. Other parameters were temperature, coagulants(Alum, $FeCl_3$), and treatment time. Water temperature greatly affected in removal rates of turbidity for sedimentation and DAF. Generally DAF was more effective in removal rates of turbidity than sedimentation at the same experimental condition. Removal rates of $UV_{254}$ were high to over 90%, and independent of temperature and coagulant.

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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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A Study on Bubbles Generated from Water Plasma for Application of DAF Process

  • Park, Jun-Seok;Yu, Seung-Yeol;Yu, Seung-Min;Hong, Eun-Jeong;Seok, Dong-Chan;Hong, Yong-Cheol;No, Tae-Hyeop;Lee, Bong-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.232-232
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    • 2011
  • DAF는 기존 침전 공정에 비해 뛰어난 정수 품질과 빠른 처리 시간으로 차세대 정수 공정으로 각광 받고 있다. DAF는 기포 생성 방법에 따라 용존 공기 부상법, 분산 공기 부상법, 진공 부상법, 전해 부상법, 미생물학적 부상법 등이 있다. 이 중 가장 많이 쓰이는 방식은 용존 공기 부상법으로, 과포화 상태의 기체와 액체의 혼합액을 압력을 급격히 감소시켜 기포를 발생 시키는 방법이다. 이 방법은 기포의 발생은 많지만 장비의 크기가 거대하고 시설제조 비용이 많이 드는 단점이 있다. 수중에서 발생되는 플라즈마는 그 구조와 메카니즘에 따라 생성되는 버블의 양을 제어할 수 있음을 확인하였다. 모세관 형태의 전극을 이용한 수중 방전은 전원 공급 장치만 있다면 적은 공간으로도 효과적으로 기포를 생성 할 수 있기 때문에, 수중 방전을 이용하여 기포 발생 후 DAF에 적용 가능한지 알아보고자 한다. DAF공정에서 필요한 요인으로는 기포의 크기, 개수, 성분 물질 등이 있는데, 그 중 가장 핵심은 기포의 크기 이다. 그래서 간단한 전원 장치와 리액터 제작 후 방전에 최적화 된 전극으로 기포를 발생시켜 기포의 크기를 측정하였다. 기포의 크기는 전극의 직경과 방전공간의 비율에 따라 제어가 가능함을 확인하였고 평균 기포의 크기는 약 50 ${\mu}m$로서, DAF에 적용 할 수 있는 크기이다. 일반적으로 기포의 사이즈가 작을수록 입자 제거율이 높은데, 실제 DAF공정에서 사용되는 기포의 사이즈는 80 ${\mu}m$정도 이다. 따라서 개발된 기포 발생장치를 DAF 공정에 응용한다면 높은 효율을 가질 것으로 판단된다.

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Changes of Seed Quality of Chinese Milk Vetch(Astragalus sinicus L.) During Seed Developmental Stages

  • Na, Chae-Sun;Lee, Yong-Ho;Hong, Sun-Hee;Jang, Cheol-Seong;Kang, Byeung-Hoa;Lee, Jong-Ki;Kim, Tae-Ho;Kim, Wook
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.52 no.4
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    • pp.363-369
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    • 2007
  • The objective of this study was to investigate the variation of Chinese milk vetch(Astragalus sinicus L.; CMV) seed quality after flowering. We tagged individual open flowers of CMV at the day of maximum flowering(11 May) in Seoul, Korea. Seed samples were harvested serially at 15, 20, 25 and 30 days after flowering(DAF). To compare with dried seeds, non-dried seeds were tested immediately after harvest and the remaining seeds were placed at room temperature for 4 weeks. Seed length, 1000 seed weight, moisture content, germination rate(GR), mean germination time(MGT), germination speed(GS), germination performance index(GPI) and physical dormancy rate(PDR) were investigated. Seed length increased to 2.6 mm and 1000 seed weight reached up to 2.2 g until 25 DAF. Seed moisture content dramatically decreased from 20 to 25 DAF. Moisture content of non-dried seed(7.5%) was similar to that of dried seed(5.5%) at 25 DAF. The rate of seed viability reached up to 94% at 25 DAF. In case of dried seed, GR increased up to 39% at 25 DAF whereas GR of non-dried seed varied from 5 to 10%. GS and GPI of dried seed were significantly higher than those of non-dried seed since 25 DAF. PDR of dried seed has decreased since 20 DAF, whereas PDR of non-dried seed has increased. GR, GS and GPI increased as PDR decreased. Our results evidenced that PDR might be one of major factor in variation of seed quality, of which development was completed at 25 DAF.