The use of a LISST-100 laser particle sizer for in-situ estimates of floc size, density and settling velocity

2001 ◽  
Vol 20 (4) ◽  
pp. 187-195 ◽  
Author(s):  
Ole Mikkelsen ◽  
Morten Pejrup
Keyword(s):  
Settling Velocity ◽  
Floc Size ◽  
Particle Sizer

A test of the ADV-based Reynolds flux method for in situ estimation of sediment settling velocity in a muddy estuary

2013 ◽  
Vol 33 (6) ◽  
pp. 477-484 ◽  
Author(s):  
Grace M. Cartwright ◽  
Carl T. Friedrichs ◽  
S. Jarrell Smith
Keyword(s):  
Settling Velocity ◽  
Flux Method ◽  
Sediment Settling

scholarly journals Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 999
Author(s):  
Ahmad Shakeel ◽  
Zeinab Safar ◽  
Maria Ibanez ◽  
Leon van Paassen ◽  
Claire Chassagne
Keyword(s):  
Light Scattering ◽  
Shear Rate ◽  
Settling Velocity ◽  
Rheological Analysis ◽  
Floc Size ◽  
Clay Concentration ◽  
History Of ◽  
Settling Column ◽  
Cationic Polyelectrolytes ◽  
Shear History

The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on the fact that the clay concentration possible to analyze with selected experimental methods was significantly different. The optimum flocculant to clay ratio was defined as the ratio that gives the fastest initial floc growth by static light scattering or fastest initial settling velocity by settling column experiments. In case of anionic polyelectrolyte, it was observed that the optimum flocculant dose depends on the amount of cations present in the system. For suspensions made with demi-water, a lower optimum flocculant dose (<1 mg/g) than for suspensions prepared in tap water (2.28 mg/g) was observed. At these lower salinities, the supernatant remained turbid in all the experiments and was, therefore, not a good measure for optimal anionic based flocculation. The equilibrium floc size at a given shear rate was found to be independent on the shear history of the floc and only dependent on the current applied shear. This was confirmed by both light scattering and rheological analysis. In case of cationic polyelectrolyte, the optimum flocculant ratio (5–6 mg/g) corresponded to the ratio that gives the lowest electrophoretic mobility for each clay concentration and to the ratio that gives the fastest settling velocity for the highest clay concentrations (12–15 g/L), where static light scattering measurements were not possible. All investigation techniques, therefore, proved to be good indicators for predicting the optimum flocculant to clay ratio. For the lowest concentrations (1.75–8.7 g/L) studied by settling column measurements, the optimum flocculant ratio was observed to increase with decreasing clay concentration, for fixed mixing conditions. The optimum flocculant to clay ratio was not always corresponding to the clearest supernatant and the size of flocs at optimum dosage was dependent on the mixing efficiency. The equilibrium floc size at a given shear rate was found to be dependent on the shear history of the floc and the current applied shear. This was confirmed by both light scattering and rheological analysis.

A comparison of in situ techniques for estuarine floc settling velocity measurements

1996 ◽  
Vol 36 (1-2) ◽  
pp. 15-29 ◽  
Author(s):  
K.R. Dyer ◽  
J. Cornelisse ◽  
M.P. Dearnaley ◽  
M.J. Fennessy ◽  
S.E. Jones ◽  
...  
Keyword(s):  
Settling Velocity ◽  
Velocity Measurements ◽  
In Situ Techniques

Practical design of flocculator for new polymeric inorganic coagulant - PSI

2004 ◽  
Vol 4 (1) ◽  
pp. 67-75 ◽  
Author(s):  
K. Ohno ◽  
M. Uchiyama ◽  
M. Saito ◽  
T. Kamei ◽  
Y. Magara
Keyword(s):  
Settling Velocity ◽  
Design Parameters ◽  
Mixing Process ◽  
Kaolinite Clay ◽  
Floc Size ◽  
Rapid Mixing ◽  
Water Purification System ◽  
Purification System ◽  
Practical Design ◽  
Slow Mixing

Physical characteristics of flocs formed by new polymeric inorganic coagulant, polysilicato-iron coagulant (PSI) were investigated using kaolinite clay suspended water as test water. Floc density was determined by measuring floc settling velocity and spherical equivalent floc diameter. The floc density function proposed by Tambo and Watanabe could be applied to PSI. Flocs formed by PSI showed higher floc density than those formed by alum at the same floc size. Floc size distribution after the rapid mixing as also determined. PSI could produce well-grown flocs at the stirring speed of 300 rpm. Stirring at 300 rpm for 7 minutes, residual turbidity after 15 minute sedimentation became lower than rapid mixing at 120 rpm for 5 minutes followed by slow mixing at 40 rpm for 25 minutes. Flocs formed by PSI was much stronger than those formed by alum. Using the data obtained, the design parameters of flocculator by use of PSI were estimated following Tambo and WatanabeÕs procedure. According to the estimation, it was suggested that rapid mixing process alone can make well-grown flocs and slow mixing process, which is essential for the conventional water purification system using aluminium coagulants, can be eliminated by use of PSI.

scholarly journals Tidal Variation in Cohesive Sediment Distribution and Sensitivity to Flocculation and Bed Consolidation in An Idealized, Partially Mixed Estuary

2019 ◽  
Vol 7 (10) ◽  
pp. 334 ◽  
Author(s):  
Tarpley ◽  
Harris ◽  
Friedrichs ◽  
Sherwood
Keyword(s):  
Settling Velocity ◽  
Transport Model ◽  
Tidal Flow ◽  
Sediment Concentration ◽  
Tidal Variation ◽  
Model Framework ◽  
Sediment Distribution ◽  
Floc Size ◽  
Size Classes ◽  
Suspended Floc

Particle settling velocity and erodibility are key factors that govern the transport of sediment through coastal environments including estuaries. These are difficult to parameterize in models that represent mud, whose properties can change in response to many factors, including tidally varying suspended sediment concentration (SSC) and shear stress. Using the COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) model framework, we implemented bed consolidation, sediment-induced stratification, and flocculation formulations within an idealized two-dimensional domain that represented the longitudinal dimension of a micro-tidal, muddy, partially mixed estuary. Within the Estuarine Turbidity Maximum (ETM), SSC and median floc diameter varied by a factor of four over the tidal cycle. Downstream of the ETM, the median floc size and SSC were several times smaller and showed less tidal variation (~20% or less). The suspended floc distributions only reached an equilibrium size as a function of SSC and shear in the ETM at peak tidal flow. In general, flocculation increased particle size, which reduced SSC by half in the ETM through increased settling velocity. Consolidation also limited SSC by reduced resuspension, which then limited floc growth through reduced SSC by half outside of the ETM. Sediment-induced stratification had negligible effects in the parameter space examined. Efforts to lessen the computation cost of the flocculation routine by reducing the number of size classes proved difficult; floc size distribution and SSC were sensitive to specification of size classes by factors of 60% and 300%, respectively.

ROST and BEAST: Devices for in-situ measurement of particle settling velocity

1985 ◽  
Vol 66 (1-4) ◽  
pp. 381-395 ◽  
Author(s):  
R. Bartz ◽  
J.R.V. Zaneveld ◽  
I.N. McCave ◽  
F.R. Hess ◽  
A.R.M. Nowell
Keyword(s):  
Settling Velocity ◽  
In Situ Measurement ◽  
Particle Settling
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