• Title/Summary/Keyword: settling test

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An Experimental Study on Characteristics of Sedimentation of Dredged Soil (준설토의 침강특성에 관한 실험적연구)

  • Yoo, Nam-Jae;Lee, Jong-Ho;Jun, Sang-Hyun;Lee, Jong-yong
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.113-122
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    • 2000
  • Column tests in the laboratory were preformed to investigate characteristics of settling process of dredged soil sampled from in-situ. Test results were analyzed by using the existing theories on discrete settling and hindered settling. From column tests of monitoring the interface with time, settling was found to be a linear process with time and the settling rate was increased with initial water content of slurry. The settling rate was also observed to decrease with increasing initial height of slurry. Most of settling process were composed of flocculation, hindered settling and self-weight consolidation. On the other hands, flocculation of soil during settling was observed and it was found that the size and density of flocculated particles could be analyzed by using the method proposed by Richardson and Zaki.

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Settling Mode of the Dredged Soil (준설토의 침강형태에 관한 연구)

  • 윤상묵;장병욱;차경섭
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.1
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    • pp.63-73
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    • 2003
  • The settling of the dredged soil may vary with mineral composition, grain size distribution, initial water content and salt concentration of suspension of the site. A series of settling column test was performed to investigate the behaviour of solid suspension material from dredging and reclamation. Settling mode was divided into four types from the observation of interface and settling curves of clay minerals and marine clay samples, and the relationship charts of salt concentration and the initial water content were established to use in the dredging operation with any salt concentration. The critical initial water content which was defined as a threshold of zone settling and the consolidation settling was varied with salt concentration of water and was proportional to the plasticity of soil in sea water.

Settling Characteristics of Water Treatment Plant Sludges by Pretreatment Methods (정수장슬러지의 전처리에 의한 침전특성)

  • Moon, Yong-taik;Lee, Sun-ju
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.6
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    • pp.627-632
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    • 2008
  • It is necessary to investigate methods for improvement by diagnosing sludge settling characteristics on inflow of slurry to thickener. The results of the settling tests are correlated to determine zone settling velocities at the various sludge solids concentrations. Conditioning of WTP residuals is generally done by either chemical or physical treatment. The settling test was conducted with 1m columns dosing polymer to WTP residuals at various solids concentration. The estimated results for dosing to WTP residuals for a sludge of 2,100 ~ 16,012 mg/L solids concentration were the zone settling velocities of 48.38 ~ 6.8 m/day, supernatant solid concentration of 3.2 ~ 19 mg/L and solid flux of $101.6{\sim}317.61kg/m^3{\cdot}day$. The values for non-polymer treatment were the zone settling velocities of 28.37 ~ 0.12 m/day, supernatent solid concentration of 8.5 ~ 108 mg/L and solid flux of $59.58{\sim}1.92kg/m^2{\cdot}day$. The limiting solid flux value by Yoshioka methods was $4.0kg\;TS/m^3{\cdot}day$ for Non-polymer and $228.0kg\;TS/m^3{\cdot}day$ for dosing polymer. These results are to indicate a possibility of improvement on the thickening characteristics and the quality of supernatant as increasing the settling velocities by dosing polymer to WTP residuals.

A Model for Settling Rate of the Dredged Soil (준설토의 침강속도 추정모델의 개발)

  • Yun, Sang-Muk;Chang, Pyoung-Wuck;Won, Jung-Yun;Kim, Sung-Pil
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.1
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    • pp.51-59
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    • 2005
  • The settling rate of the dredged soil may vary with mineral composition, grain size distribution, initial con contration and salt concentration of suspension of the site. A series of settling column test was performed to investigate the settling rate characteristics of solid suspension material from dredging and reclamation. The settling rate of soil mixed with various size of particles depended on clay fraction which showed a inherent flux. A model was developed to predict the particle flux of mixed soil from the clay flux and its applicability was verified.

An Experimental Study on Parameter Estimation of Settling and Erosional Properties for Cohesive Sediments in Shihwa Lake (시화호 점착성 퇴적물의 침강.침식 특성 매개변수 산정에 대한 실험적 연구)

  • Ryu Hong-Ryul;Hwang Kyu-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.18 no.3
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    • pp.179-188
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    • 2006
  • The purpose of this study is to quantitatively estimate the settling and erosional properties for cohesive sediments in Shihwa lake. Settling tests are conducted by multi-depth method using a specially designed 1.8 m tall settling column, and erosion tests are conducted with annular flume under the uniform bed condition. As result of settling tests, it is confirmed that the settling velocity of the cohesive sediments has the range of $0.002 for suspended sediments concentration of 0.1$0.19{\sim}0.55N/m^{2}$ for bed shear stress of $1.14{\sim}1.32g/cm^{3}$, and the erosion rate coefficient decreases with logarithmic function in a range of $18.4{\sim}3.9mg/cm^{2}{\cdot}hr$ with increase of bed shear stress.

Characteristics of Settling and Consolidation Behavior for Non-Plastic Dredged Soils (비소성 준설토의 침강-압밀 거동 특성)

  • Park, Yun-Gyun;Park, Byung-Soo;Jeong, Gil-Soo;Yoo, Nam-Jea
    • Journal of Industrial Technology
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    • v.24 no.A
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    • pp.251-261
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    • 2004
  • A series of column test with a silty marine soil mixed with Jumunjin Standard Sand were performed to investigate the characteristics of settling and consolidation of non-plastic dredged soils. Column tests were carried out by using the separable column to measure the grain size distribution of consolidated layer. Column tests were performed with changing the mixing ratio of Jumunjin Standard Sand to the silty marine soil, initial water content of slurry and initial height of slurry. Height of interface of slurry was monitored during tests and grain size distribution tests were carried out after finishing tests. Influencing factors on the particle segregation, eventually to the characteristics of settling and consolidation of non-plastic soil, were analyzed on the thesis of test results. As results of column tests, the mixing ratio of sand to the silty marine soil and the initial water content of slurry were known to affect the characteristics of settling and consolidation resulted in significant particle segregation of slurry. Initial height of slurry was found not to affect seriously to particle segregation.

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Reduction of Pollutant Concentrations in Urban Stormwater Runoff by Settling (침강에 의한 도시 강우 유출수 오염물질 저감 특성 분석)

  • Seo, Dongil;Kim, Jaeyoung
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.4
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    • pp.210-218
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    • 2016
  • The pollutant removal efficiencies of stormwater runoff by settling were analyzed using field samples collected in 4 different raining events in a test bed installed in the Gwanpyung-Cheon stream in Daejeon. A 1.8 m high with 30 cm diameter cylindrical settling device was used for the settling test by measuring concentration of TSS, TP and TN for time and height. The pollutants removal rate was relatively high in the first 4 hours while 24 hours seem to be necessary to reach steady state in pollutant concentrations. However, there were no considerable differences in concentrations for height at a given time. This indicates most of particulate pollutant in the test seems to show independent settling with no interference to each other. Much part of particle sizes were distributed in the range of $10{\sim}100{\mu}m$. Average particulate fractions of TP and TN were estimated as 52.4% and 23.5%, respectively. This results explain why TN is difficult to remove by simple settling. This study indicates that a simple settling can provide effective method to remove significant amount of TSS and TP effectively and this can be used to protect urban river water quality.

An Experimental Research About Settling and Consolidation Characteristic of Dredged Soil in West Coast (서해안 준설토의 침강압밀특성에 관한 실험적 연구)

  • Lee, Seung-Ho;Lee, Jeong-Hak
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.5
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    • pp.29-36
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    • 2011
  • In this study, settling experiment was performed about cohesive and sandy soils among representative sample expected to dredge and dump for analysis of settling and consolidation characteristic. The analysis showed the definite difference between cohesive soils and sandy soils of relationships with settling and consolidation coefficient, a water content, interfacial heights. But directly after a dredged reclamation, prediction results about a initial volume change showed that cohesive soil of a water content change was decreased rapidly as time goes by, but sandy soils made no difference in a water content change. Results were compared and analyzed with the settling and consolidation coefficient and a initial settling velocity by real soil amounts for a feasibility check about test conditions applied to these experiment: we judge that test conditions are appropriate, each material by such these analyses suggests the scope of settling and consolidation coefficient, average and the representative relational formula.

여천지역 준설.매립토의 침강압밀 특성

  • Song, Jeong-Rak;Baek, Seung-Hun;Yeo, Yu-Hyeon
    • Proceedings of the Korean Geotechical Society Conference
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    • 1992.10a
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    • pp.55-60
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    • 1992
  • Hydraulically filled ground is formed by the settling of soil grains from the mixture of soil grains and water. It was generally known that the settling speed of the soil grains in governed by Stokes low. In the case of clayed dredged material, the shape of soil grains is not round, the surface of the soil grains is relatively large compared to the weight of soil grains and inter-grain ionic force is relatively large compared to the wight of soil grains. By this reason the settling and consolidation behavior of hydraulically filled quite different from that of Stokes law. This study investigated the settling and consolidation behavior of hydraulically filled materials of Yeochon industrial complex by large scale laboratory settling & consolidation container. The test results showed tat actual settling speed of soil grains in quite large compared to that of Stokes law. It was turned out that this phenomenon was due to the aggregation of soil grains. Also, it was truned out that the void ration and water content after the completion of settling process was 8.7 and 322% respectively. The consolidtion settlement of clayey hydraulic fill material was predicated better by "incremental small strain" consolidation concept than classical Terzaghj's consolidation concept (infinitesimal strain).

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Effect of Hydraulic Property and Mixing Intensity of Flocculation Basin on Flocculation Efficiency in Water Treatment Plant (정수장 플록형성지의 수리학적 특성과 교반강도가 플록형성 효율에 미치는 영향)

  • Jung, Yong-Jun;Min, Kyung-Sok
    • Journal of Korean Society on Water Environment
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    • v.21 no.3
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    • pp.230-235
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    • 2005
  • The main purpose of the flocculation process is to make flocs bigger to be removed easily in the following processes. The flow pattern and mixing intensity have a great influence on flocculation. In this study, the flow pattern was examined by a hydraulic tracer-test, where 3 water treatment plants having $800,000m^3/d$, $44,000m^3/d$ and $40,000m^3/d$ were employed. Also, the settling test was conducted to find out the relationship between the mixing intensity and the settling ability of flocs. The hydraulic tracer-test was conducted for the various flocculation processes that have different structures of flocculation basins. In the result, the retention time distribution (RTD) curves for the flocculation processes were quite different. In case of the inappropriate structure of the flocculation basin, the flow is not even so that the floc does not grow enough. To find out the relationship between mixing intensity and settleability of flocs, G-values were calculated and the settling test was conducted for two flocculation basins which have the same conditions except the G-value. For the flocculation basin with uneven G-value, the floc settleability was revealed poor. On the other hand, the flocculation basin with even G-value, the settleability was better than the previous one. From these experimental results, it is confirmed that the flow pattern is closely related to the structure of the flocculation basin and the settleability is affected by mixing intensity. Therefore the flow pattern and the strength of the mixing intensity should be examined sufficiently to design and operate flocculation basin.