• Title/Summary/Keyword: Sedimentation of particles

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Formation of Sedimentation Pool within Irrigation Reserviors for Water Quality Improvement (저수지 수질개선을 위한 저수지 내 침전지 조성)

  • 박병흔
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.42 no.1
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    • pp.73-82
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    • 2000
  • Large quantitive of polllutants are washed into reservoirs during storm events. These polllutants contribute to eutrophication, such as algal blooms and fish kills. This study was conducted for the purpose of assessing the pollutant removal possibilities of sedimentation pool formed by deep dredging of a reservoir inlet. Water quality data were collected in the Masan reservoir, whose inlet has been dredged deep like sedimentation pool. The average concentration of chemical oxygen demand(COD) , toatal nitrogen(T-N) and total phosphrous(T-P) in the deep dredged area were 8.7 ~20.5mg/ι (T-N), 0.17~0.84mg/ι(T-P), which were 4.9%(COD), 29.0%(T-N) and 44.8%(T-P) higher than those of middle part of the reservior. The texture of sediment in the dredged area was silty loam, while that of the middle part was sandy clay loam. Organic matter contents, T-N and T-P of the bottom soil in the dredge area showed higher values than the middle part of the reservoirs. From these results, it was considered thedeep dredged area in the inlet of reservoir might play a key role to settle pollutant particulate. Based on the result of water quality analysis, deep dredging of the reservoir inlet could be assessed to reduce T-N and T-P of the reservoir about 6.5% , 8.3%, respectively. However, the effect of the sedimentation pool would be raised if the settled particles were taken into account in assessing water quality improvement for the reservoir. Accordingly, dredging of a reservoir inlet to make a shape of sedimentation pool is recommended for water quality improvement of reservoir in the stage of dredging plan.

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Removal of Endotoxins and Nucleic Acids Using Submicron-sized Polymeric Particles

  • Kim, Chan Wha;Chokyun Rha
    • Journal of Microbiology and Biotechnology
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    • v.6 no.3
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    • pp.189-193
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    • 1996
  • Submicron-sized polymeric particles (SSPP) were used to remove nucleic acids and endotoxins from cell lysates. The positively charged SSPP selectively adsorb nucleic acids and endotoxins and form complexes with them. The complexes can be easily removed by sedimentation or centrifugation. The removal of nucleic acids and endotoxins using SSPP also can be accomplished in the presence of cell and cell debris. Therefore, nucleic acids and endotoxins can be removed in an initial step of the down-stream processes. In bakers yeast and E. coli lysate systems, the level of DNA could be reduced more than three orders of magnitudes and endotoxins more than seven orders of magnitudes concurrently willi the cell debris removal process using SSPP.

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VALIDATION OF NUMERICAL APPROACH FOR THE SEDIMENT OF MULTI-SIZE PARTICLES IN A FLUID CONTAINER (다양한 크기를 갖는 입자들의 유체 용기 내부에서의 침전에 대한 수치적 접근방법의 검증)

  • Ji, Youngmoo;Choi, Sangmin
    • Journal of computational fluids engineering
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    • v.18 no.2
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    • pp.93-98
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    • 2013
  • In this paper, we reported the verification of numerical simulation approach for sedimentation of the multi-size particles in a container. The comparison between experimentally measured values and numerically evaluated values on settle down process of fully mixed mixture is carried out. In an attempt to represent the natural particle size distribution, various diameters of single particles are simulated and the results are compared with the outcome of the multi-size computation. When the empirical formula for mean particle size estimation is adopted to define the sediment diameter, computation and comparison are conducted.

Studies on Flacherie and Ina-flacherie Viruses of the Silkworm, Bombyx mori I. Purification of Viruses (가잠의 연화병바이러스에 관한 연구 I. 연화병바이러스의 정제)

  • 강석권
    • Journal of Sericultural and Entomological Science
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    • v.19 no.1
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    • pp.25-32
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    • 1977
  • The flacherie (FV) and Ina-flacherie (Ina-FV, named arbitarily) viruses of the silkworm, Bombyx mori was isolated from infectious larvae. Two types of infectious particles were purified by sucrose density gradient centrifugation. Some properties of the purified particles were investigated. Electron micrographs showed that FV and Ina-FV were spherical particles with diameters of 27nm and 20nm, respectively. The sedimentation coefficient of Ina-FV was 80S.

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Effect of Suspension in AC Electrowetting (교류 전기습윤에서 부유물의 영향)

  • Ko, Sung-Hee;Oh, Jung-Min;Kang, Hwan-Hyoung
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.379-382
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    • 2006
  • We are investigating the effect of particle on electrowetting, and this paper reports the experimental results obtained until now. The experiment was performed for different particle sizes, electrolyte concentration, and AC frequencies. The problem is quite complicated by various factors, such as the existence of surfactant in suspension and sedimentation of particles. We could not draw a concrete conclusion on the effect of particles, and it needs further investigations. We also report interesting phenomena observed during the experiment. It includes the droplet generation at the edge of a droplet, pseudo-bistability of electrowetting, flow generation inside a droplet, and the chain formation of particles inside a droplet.

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Modeling of Sedimentation and Vertical Dispersion of Coastal Sediment Particles Contaminated with PCBs (PCB로 오염된 연안 퇴적물 입자의 침강 및 연직확산 모델연구)

  • Lee Du Gon
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.1 no.1
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    • pp.39-46
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    • 1998
  • This study presents a numerical model that can simulate changes of particle size distribution (PSD) of PCB-contaminated coastal sediments. The developed model has one spatial dimension including sedimentation and vortical dispersion as well as coagulation. The reason for considering the vortical transport mechanisms is to calculate residence time of the particles. Using the model and Initial PSD data based on actual coastal sediments contaminated with PCBs, this study shows results of model simulations. Within 48 hours of the simulation time, the PSD changed significantly and the particles were removed from water in different rates between different particle sizes. It also shows that coagulation can act an important role in this process. The model may be useful in assessing the range of resuspended sediments that can pollute neighboring areas during environmental remediation projects such as dredging.

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Enhancement of the Escherichia coli Floc Strength with Water Soluble Polymers

  • KIM, CHAN-WHA;CHOKYUN RHA
    • Journal of Microbiology and Biotechnology
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    • v.7 no.4
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    • pp.282-286
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    • 1997
  • The floc strength of Escherichia coli was enhanced by adding water soluble polymer flocculants (BPA-5020 and BPA-5000) to the particulate flocculant (BPA-1000) as indicated by the increase in the shear index. The shear index of the E. coli flocs increased from 0.39 with the particulate flocculant alone to 0.94 with the particulate flocculant in conjunction with the water soluble polymer flocculant. In addition, the sedimentation rate of flocs was higher and the sedimented volume of flocs was smaller when the particulate flocculant was used with the water soluble polymer flocculant. When E. coli was flocculated first with the water soluble flocculant and the particulate flocculant was added later into the E. coli flocs formed, the sedimentation rate of the flocs was greater than that of any other combination. The shear index of the flocs was, however, independent of the sequence of the flocculant addition.

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Electrokinetic Sedimentation and Remediation of River Dredged Contaminated Soil (오염된 하천준설토의 동전기적 침강 및 오염물질 제거)

  • 정하익;오인규;진현식
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.559-562
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    • 2001
  • There are many engineering applications that demand settling acceleration and volume reduction of fine solid suspensions. It is a matter to Improve the dredged soil thickening as well as the dewatering characteristic, because settling acceleration of dredged soil decreases the scale of industrial process and volume reduction of dredged soil decreases environmetal challenge to the disposal sites. Direct electric current induces the movement of fine solid particles suspended in water. Upon formation of a soil structure, the current further induces the movement of water and contaminant in the soil skeleton. Theses phenomena are known as electrokinetics. This study investigates the viability, of using the technique of electrokinetic dewatering to river dredged soil for settling acceleration and volume reduction. The aspect, such as sedimentation velocity, final volume and current variation are discussed.

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Role of surfactant on damping performance of polyaniline based electrorheological suspension

  • Kim, Ji-Woo;Kim, Chul-Am;Choi, Hyoung-Jin;Choi, Seung-Bok
    • Korea-Australia Rheology Journal
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    • v.18 no.1
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    • pp.25-30
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    • 2006
  • To enhance the stability of dispersed polyaniline (PANI) particles in a silicone oil system, a nonionic surfactant was adopted, and its effect on the electrorheological (ER) performance was investigated under an applied electric field. In the presence of a nonionic surfactant, the PANI based ER fluid exhibited not only an improved sedimentation stability based on the estimated sedimentation ratio but also an enhanced maximum yield stress behavior. Furthermore, the surfactant added ER suspension was applied to an ER damper system, and its damping performance was compared with the ER suspension without a surfactant.

Simulation of Various Baffle Types in a Constructed Wetland Sedimentation Tank using CFD (CFD를 이용한 Hybrid 인공습지의 초기침강지 저류판 구조 모의)

  • Noh, Taegyun;Jeon, Jechan;Kim, Lee-Hyung
    • Journal of Wetlands Research
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    • v.18 no.3
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    • pp.324-329
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    • 2016
  • Constructed wetlands are widely applied in urban and rural areas for various purposes such as pollutants reduction, acquisition of eco-spaces and habitats, flooding reduction, acquisition of water resources and environmental education. Since the design of constructed wetlands utilizes ecosystems, special consideration must be given to ecological mechanisms, environmental mechanisms and hydrological mechanisms. To ensure the sustainable functionality of constructed wetlands, it is necessary to achieve stable flow rate and velocity, and remove sediments to ensure sufficient space for detention. To enhance the efficiency of constructed wetland sedimentation basins, this study determined the optimal position for baffle installation, and applied Computational Fluid Dynamics (CFD) to the cross-sectional design of wetlands. CFD analysis revealed that the decrease in flow velocity with baffle installation enhanced the efficiency of sedimentation of particulate matters. Vertical baffles had higher sedimentation efficiency than those with an inclined angle. When vertical baffles were installed in the sedimentation basin of a hybrid constructed wetland to reduce non-point source pollutants in urban areas, the average flow velocity within the basin decreased by 10~30%, while the sedimentation efficiency improved by 1.3~1.5 times. The application of CFD to constructed wetlands is expected to improve the cost efficiency of designing hybrid constructed wetlands with high removal efficiency.