Shear-induced flocculation of a suspension of kaolinite as function of pH and salt concentration

Mietta, F.; Chassagne, Claire; Winterwerp, Johan C.

doi:10.1016/j.jcis.2009.03.044

Cited by 89 publications

(60 citation statements)

References 18 publications

(33 reference statements)

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“…For example, flow velocity and turbulence (depending on its intensity) promote aggregation of cohesive sediments or disaggregation (i.e., breakage) of large flocs [6][7][8]. Water chemistry parameters, such as pH, salinity, and multivalent cations, may change the attractive and repulsive forces of cohesive sediments [9,10]. Extracellular polymeric substances (EPS) can enhance flocculation as a polymeric flocculation agent [11,12].…”

Section: Introductionmentioning

confidence: 99%

Seasonal Variation in Flocculation Potential of River Water: Roles of the Organic Matter Pool

Lee

Hur

Toorman

2017

Water

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Organic matter in the water environment can enhance either flocculation or stabilization and, thus, controls the fate and transportation of cohesive sediments and causes seasonal variation in the turbidity of river water, determining floc morphology and settling velocity. The aim of this study was to elucidate the way that biological factors change the organic matter composition and enhances either flocculation or stabilization in different seasons. Jar test experiments were performed using a mixture of standard kaolinite and the filtered river water samples collected (bi-)weekly or monthly from April to December 2015 upstream a constructed weir in Nakdong River, to estimate the flocculation potential of the seasonal river water samples. Chlorophyll-a concentration, algae number concentration, and the fluorescence characteristics of organic matter were used to represent the biological factors. Our results revealed that flocculation potential depended not only on the algal population dynamics, but also the origins (or chemical composition) of organic matter in the river water. Extracellular polymeric substances (EPS), as algal organic matter, enhanced flocculation, while humic substances (HS), as terrestrial organic matter, enhanced stabilization, rather than flocculation. Since flocculation potential reached its maximum around the peaks of algal population, algae-produced EPS likely enhanced flocculation by binding sediment particles in the flocs. This observation supports previous findings of seasonal variation in EPS production and EPS-mediated flocculation. However, when HS was transported from the surrounding basin by a heavy rainfall event, cohesive sediments tended to be rather stabilized. Supplementary flocculation potential tests, which were performed with artificial water containing refined EPS and HS, also showed the opposing effects of EPS and HS.

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Section: Introductionmentioning

confidence: 99%

Seasonal Variation in Flocculation Potential of River Water: Roles of the Organic Matter Pool

Lee

Hur

Toorman

2017

Water

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“…The results will be expressed as a ''Smoluchowsky zeta potential", i.e., the zeta potential obtained from electrophoresis using the Smoluchowsky formula, to follow what many other authors do. These data will be used in another article [17] to interpret aggregation measurements performed on the same samples.…”

Section: Introductionmentioning

confidence: 99%

Electrokinetic study of kaolinite suspensions

Chassagne

Mietta

Winterwerp

2009

Journal of Colloid and Interface Science

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“…They are considered as of the same order of magnitude than the size of the largest flocs (Bouyer et al 2004, Mietta et al 2009. Average Kolmogorov microscale (η) corresponding to turbulent kinetic energy (TKE) generated by grid oscillations of 3 and 12 s period were 272 and 1021 µm, respectively (Matsunaga et al 1999, Jansen et al 2003, which was close to those measured in Cam estuary during dry season of 2009 for mid ebb and slack water; 256 and 950 µm, respectively.…”

Section: Oscillating-grid Turbulence (Ogt)mentioning

confidence: 57%

The Role of Tep in Estuarine Hydrosedimentary Functioning: Impact on Settling Velocity of Aggregates

Lefèbvre¹,

Mari²,

Thao

et al. 2014

Int. Conf. Coastal. Eng.

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Transparent exopolymer particles (TEP) are widely recognized to promote sediment aggregation in eutrophic environments. Flocculation in presence of TEP of various suspended sediment concentrations of material sampled on the bank of the Cam River was quantified at the laboratory for turbulence level consistent with slack water and mid ebb conditions measured in the Cam River estuary during dry season of 2009. Stickiness and concentrations of TEP were let to naturally fluctuate by incubation (aging in the dark) for up to nine days. We found that the impact of turbulence on overall buoyancy of TEP-governed aggregation was always opposite between slack water and mid ebb conditions for any duration of incubation; always negative for slack water conditions but for 126 hours of incubation and significantly negative for mid ebb conditions but for 126 hours of incubation. Suspended sediment concentration (SSC) consistently limited aggregates buoyancy, negative or positive. We propose a conceptual model that relates measured and inferred parameters to observed hydrosedimentary processes.

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Shear-induced flocculation of a suspension of kaolinite as function of pH and salt concentration

Cited by 89 publications

References 18 publications

Seasonal Variation in Flocculation Potential of River Water: Roles of the Organic Matter Pool

Seasonal Variation in Flocculation Potential of River Water: Roles of the Organic Matter Pool

Electrokinetic study of kaolinite suspensions

The Role of Tep in Estuarine Hydrosedimentary Functioning: Impact on Settling Velocity of Aggregates

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