• Title/Summary/Keyword: Flocculation

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Flocculation kinetics and hydrodynamic interactions in natural and engineered flow systems: A review

  • Oyegbile, Benjamin;Ay, Peter;Narra, Satyanarayana
    • Environmental Engineering Research
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    • v.21 no.1
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    • pp.1-14
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    • 2016
  • Flocculation is a widely used phase separation technique in industrial unit processes and is typically observed in many natural flow systems. Advances in colloidal chemistry over the past decades has vastly improved our understanding of this phenomenon. However, in many practical applications, process engineering still lags developments in colloidal science thereby creating a gap in knowledge. While significant progress has been made in environmental process engineering research over the past decades, there is still a need to align these two inter-dependent fields of research more closely. This paper provides a comprehensive review of the flocculation mechanism from empirical and theoretical perspective, discuss its practical applications, and examines the need and direction of future research.

Establishment of the Refined Model for Prediction of Flocculation/Sedimentation Efficiency Using Model Tree Technique (Model Tree기법을 이용한 정수처리공정에서의 응집/침전 효율 예측에 관한 연구)

  • Park, No-Suk;Park, Sang-Young;Kim, Seong-Su;Jeong, Nam-Jeong;Lee, Sun-Ju
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.6
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    • pp.789-797
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    • 2006
  • This study was conducted to establish the refined model for prediction of flocculation/sedimentation efficiency in factual drinking water treatment plants using model tree technique. In order to carry out machine leaning for determining each linear model, five parameters; time, coagulant dose, raw water turbidity, SCD and conductivity, which were measured and collected from the field (K_DWTP), were selected and used. The existing analytical models developed by previous researchers were used only to examine closely the mechanism of flocculation rather than to apply it for practical purpose. The refined model established using model tree technique in this study could predict the factual sedimentation efficiency accurately (below 9% of average absolute error). Also, in aspect of engineering convenience, without any additional manipulation of parameters, it can be applied to practical works.

Effect of Branch Degree of Cationic Acrylamide Copolymers on Flocculation Properties

  • Son, Dong-Jin;Kim, Bong-Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.44 no.2
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    • pp.8-17
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    • 2012
  • Three kinds of cationic acrylamide copolymer with different branch degree were prepared controlling the dosage of N, N'-methylenebisacrylamide. The physical characteristics of the branch-degree-modified copolymers were analyzed by intrinsic viscosity and charge density. The branch degree measurements were investigated by applying the colloidal titration phenomena using a spectrophotometer and comparison with the cationic regain measurement method. The results showed that the absorbance behaviors of spectrophotometer were distinctively different with the branch degree of copolymers. Also, the branch degree determinations and molecular structure estimations of the copolymers were numerically measured by applying the titration phenomena using a spectrophotometer. Finally, three kinds of branch-degree-modified copolymers were applied to flocculation test using arbocel micro pulp for the determination of flocculation behavior by different morphology of cationic acrylamide copolymers.

Effects of Polyelectrolyte Dosage, Kaoline Particles and pH on Flocculation of Humic Acid by Catonic Polyelectrolytes

  • Kam, Sang-Kyu;Kim, Dae-Kyoung;Lee, Min-Gyu
    • Journal of Environmental Science International
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    • v.12 no.8
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    • pp.861-870
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    • 2003
  • Using a simple continuous optical technique, coupled with measurements of zeta potential, the effects of polyelectrolyte dosage, kaoline particles and pH on flocculation of humic acid by several cationic polyelectrolytes, have been examined. The charge density of a polyelectolyte is important in determining the optimum dosage and in the removal of humic acid. The optimum dosage is less for the polyelectrolytes of higher charge density and is the same regardless of the presence of kaoline particles of different turbidity. At the dosage, the removal of humic acid is higher for the polyelectrolytes of higher charge density and the zeta potential of humic acid approaches to near zero, With increasing pH of humic acid, the optimum dosage increases and the flocculation index value obtained at the dosage decreases in the following pH 7 > pH 5 > pH 9, regardless of polyelectrolytes.

Optimization of Microalgae Harvesting Using Flocculation and Dissolved Air Floatation (Flocculation과 Dissolved Air Floatation을 이용한 미세조류 수확 최적화)

  • Kwon, Hyuck-Jin;Jung, Chang-Kyou;Kim, Nam-Hoon;Lee, Jin-Won
    • KSBB Journal
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    • v.27 no.2
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    • pp.103-108
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    • 2012
  • The harvesting of microalgae is a critical step that precedes biodiesel conversion. The most widely used harvesting technology is flocculation and floatation. In this study, the efficiency of the flocculants aluminum sulfate and poly aluminum chloride were evaluated for harvesting the alga Dunaliella tertiolecta in conjunction with dissolved air floatation. Using the jar test the optimum concentration range for aluminum sulfate was 1.0~1.5 g/L and for poly aluminium chloride, 1.5~2.0 g/L. The degree of coagulation was visualized by microscopy. Further analysis in combination with dissolved air floatation showed that the optimal concentration for aluminum sulfate was 1.1 g/L and for poly aluminum chloride, 1.6 g/L.

Coagulation and Flotation Conditions of Humic Acid by Dissolved Air Flotation

  • Lee, Chang-Han
    • Journal of Environmental Science International
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    • v.21 no.9
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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).

A Study on the flow Characteristics of a Horizontal Paddle Flocculator Installed in a Filtration Plant by PIV (정수장에서의 수평축 응집기 PIV 유동해석)

  • Park, Young-Geun;Lee, Joong-Ryul;Kim, Beom-Seok;Lee, Young-Ho
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.176-177
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    • 2005
  • KOWACO - ChangWon Branch - have conducted the new study which aimed to improve flocculation performance in Mixers. The Purposes in this study were increasing flocculation efficiency by finding significant factor which was affected flow characteristics. In the result of this research we modified the error in equation of G-value and RPM which have been used till quite recently. Also we developed program auto-calculating G-value and RPM and then we had made their statistical list. We had conducted experiment with flocculation Mixer's model sized 1/10 by PIV's method. We analysed characteristic of all flow fields by changing case such as changing direction of flocculator roatation etc.

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Theoretical Approach to Calculating rms-Velocity Gradient in Flocculators (응집지 속도경사(G) 계산에 대한 이론적인 고찰)

  • Kim, Ja-Kyum
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.3
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    • pp.351-356
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    • 2004
  • Selecting appropriate G values in flocculator operation is important to produce high quality filter effluent in water treatment plants. However, misunderstanding and misleading of G calculation for the case of having power sources more than one or many paddles with one power source in a flocculation basin sometimes have led to low performance in flocculation. Theoretical analysis confirmed that the total G value in one flocculation unit having power sources more than one or with many paddles is the root-square of the sum of square of individual G value. This analysis also can give a simple calculation method of G value for designers and operators in fields.

The Component Analysis of the Bioflocculant Produced by Strain YG-02 (Strain YG-02가 생산하는 생물응집제의 성분 분석)

  • Jung, Yeon-Gon;Ko, Joon-Il;Chung, Seon-Yong
    • Journal of Korean Society on Water Environment
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    • v.35 no.3
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    • pp.201-208
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    • 2019
  • In this study, we analyzed composition of the bioflocculant, which strain YG-02 produces. First, supernatant and suspension from centrifugation of culture fluid of the strain, were used in the flocculation experiment. As a result, the SVI(sludge volume index) added with the suspension, was 182 mL/g, same as the control group with no additive, and the SVI added with supernatant, was 164 mL/g. So, the result above showed that flocculation capacity of the bioflocculant, was dependent on the substance which strain YG-02 produces, not on factors such as the body of germs. As a result of the thermostability test on substances that cause flocculation, the flocculation effect was significantly reduced, compared to the result of the flocculation test, before applying heat to the culture fluid, and it was able to assume that the substance that causes flocculation, was damaged by heat. Additionally, to understand the component of the bioflocculant, analyzation of sugar composition and fatty acid, was conducted. As a result, sugar composition was the polysaccharide consisting of glucose: lactose with molar ratio of 90.75:9.25. Fatty acid content was detected, as 0.0012 g/100g, showing that it contained glycolipid in the bioflocculant. Such results show that the bioflocculant which strain YG-02 produces, is the new bioflocculant, different from bioflocculantstudiedto date.

Application of extracellular polymeric substances (EPSs)-bioflocculant for recovery of microalgae (미세조류 분리/회수를 위한 세포외 고분자물질 생물 응집제 활용)

  • Choi, Ohkyung;Dong, Dandan;Kim, Jongrack;Maeng, Sung Kyu;Kim, Keugtae;Lee, Jae Woo
    • Journal of Korean Society of Water and Wastewater
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    • v.35 no.1
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    • pp.63-69
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    • 2021
  • Microalgae are primary producers of aquatic ecosystems, securing biodiversity and health of the ecosystem and contributing to reducing the impact of climate change through carbon dioxide fixation. Also, they are useful biomass that can be used as biological resources for producing valuable industrial products. However, harvesting process, which is the separation of microalgal biomass from mixed liquor, is an important bottleneck in use of valorization of microalgae as a bioresource accounting for 20 to 30% of the total production cost. This study investigates the applicability of sewage sludge-derived extracellular polymeric substance (EPS) as bioflucculant for harvesting microalgae. We compared the flocculation characteristics of microalgae using EPSs extracted from sewage sludge by three methods. The flocculation efficiency of microalgae is closely related to the carbohydrate and protein concentrations of EPS. Heat-extracted EPS contains the highest carbohydrate and protein concentrations and can be a best-suited bioflocculant for microalgae recovery with 87.2% flocculation efficiency. Injection of bioflocculant improved the flocculation efficiency of all three different algal strains, Chlorella Vulgaris, Chlamydomonas Asymmetrica, Scenedesmus sp., however the improvement was more significant when it was used for flocculation of Chlamydomonas Asymmetrica with flagella.