Transport Of Suspended Particles Research Articles

Analyzing Particle-Associated Pollutant Transport to Identify In-Stream Sediment Processes during a High Flow Event

Urban areas are a leading source of polycyclic aromatic hydrocarbons (PAHs) that result from combustion processes and are emitted into rivers, especially during rain events and with particle wash-off from urban surfaces. In-stream transport of suspended particles and attached PAHs is linked strongly to sediment turnover processes. This study aimed to identify particle exchange processes that contribute to the transport of suspended particles during flood events. An urban high-flow signal was tracked in high temporal resolution at two sampling sites in the Ammer River (South-western Germany). Samples were analyzed for turbidity, total suspended solids concentrations (TSS), particle-size distribution, organic carbon, and PAH. Maximum discharge and the highest TSS occurred nearly simultaneously at the upstream sampling site, whereas a temporally shifted course was observed for downstream. The total load of particles was similar, yet a decrease of PAH mass (~28%) and an increase of the particulate organic carbon (POC) content (~3.5%-points) occurred. Coarser particles (≥26 µm) dominated at the beginning of the event at both sampling sites. The signal of remobilized riverbed sediment increases downstream and leads to well-established, robust linear correlations between TSS and PAHs. This study highlights that riverbed sediment acts as intermediate storage for contaminated particles from upstream sources that shape, together with the fresh urban input, the “particle signature” of suspensions moving through catchments during high discharge conditions.

A Deep Bed Filtration Model of Two-Component Suspension in Dual-Zone Porous Medium

In the paper, a mathematical model for the filtration of two-component suspensions in a dual-zone porous medium is considered. The model consists of the mass balance equations, the kinetic equations for active and passive zones of porous medium for each component of the suspension and Darcy’s law. To solve the problem, a numerical algorithm for computer experimentation is developed on the basis of finite difference method. Based on numerical results, the main characteristics of suspension filtration in a porous medium are established. Influences of model parameters on transport and deposition of suspended particles of two-component suspension in porous media are analysed. It is shown that the polydispersity of suspension and multistage nature of the deposition kinetics can lead to various effects that are not characteristic for the transport of one-component suspensions with one-stage particle deposition kinetics. In particular, in distribution of the concentration of suspended particles in a moving fluid non-monotonic dynamics are obtained at individual points in the medium. It is shown that at the points of the medium near to the input section, the concentration of deposited particles can reach partial capacities in the passive zone.

Trace elements in the estuarine systems of the Gulf of Trieste (northern Adriatic Sea): A chemometric approach to depict partitioning and behaviour of particulate, colloidal and truly dissolved fractions

Estuaries are transitional water systems where the hydrodynamic processes governing water circulation actively influence suspended particle transport and deposition. In the estuarine mixing zone, the strong physico-chemical gradients resulting from the interaction between river freshwater and seawater may affect the distribution, mobility and fate of several potentially toxic compounds, among which trace elements are of major concern. Knowledge regarding the partitioning behaviour of trace elements would provide essential scientific support for the environmental management of estuaries. In this study, trace element occurrence and phase partitioning among suspended particulate matter, colloidal material and the truly dissolved fraction were investigated in the main Italian and Slovenian estuarine environments of the Gulf of Trieste (northern Adriatic Sea). Further information about the water quality at the river mouths was provided and, in addition to the traditional evaluation of single chemical parameters, a multi-way principal component analysis was employed in order to depict disparities among sampling sites, water layers and seasonal conditions with the final aim of evaluating trace element phase partitioning.Results indicated that the suspended particulate matter acts as the main effective vehicle for Cu, Cr, Fe, Ni and Pb, and enhanced adsorption processes resulted in elevated partitioning coefficients, especially for Fe and Pb. Although disparities occurred between sampling sites and seasons, trace elements showing affinity for the solid phase appeared to be partially bound to the colloidal material. Conversely, As and Cs prevailed in the truly dissolved fraction, especially in seawater and showed scarce affinity for both the suspended particles and colloids.

Movement of the Suspended Flow in the Open Irrigation Channels

Abstract The article deals with the issues of turbulent movement of a suspended flow in open channels. Differential equations of a suspended flow were used with considering the interaction of the fluid and solid particles. The solution of equations for steady flow was obtained by a numerical method. Field data measured in irrigation channels in Tashkent and Parkent were used to estimate the velocity distribution over the depth of the stream. Developed method for calculating the formation of velocity field in statically and dynamically stable channels considered the turbulent characteristics and the presence of suspended sediments in the stream. The possibilities of practical application of the above-mentioned differential equations to the solution of the problem of a suspended solids flow's forming a velocity field were discussed. The developed analytical formulas make it possible to determine the value of flow parameters. The result is a new generalization of the mathematical model of the velocity field formation regularity at different flow saturations with a suspension. On its basis, the method is developed for calculating the parameters of the weighing process and transport of suspended particles in open channels.

Effects of Temperature on the Transport of Suspended Particles Through Sand Layer During Groundwater Recharge

This paper presents an experimental study of suspended particle transport through sand layer using a new self-developed sand layer transportation-deposition testing system, and the study aims to identify the effects of temperature on the transport of suspended particles through porous medium. Four typical temperatures (5 °C, 15 °C, 25 °C, and 35 °C) were considered in our study, and the experiments were conducted under four size compositions and three flow velocities (1.5 cm/s, 0.2 cm/s, and 0.04 cm/s). The tests were conducted using quartz sand as the porous medium and quartz powder as particles to monitor the change in turbidity under the different conditions. The breakthrough curves were analyzed, and the results demonstrated that changes in temperature can affect the breakthrough curves, especially at the peak. The influence is particularly significant under lower flow velocities and for smaller particles. In regard to the influence factors on the transport process, water viscosity and adsorption effect can be regarded as promoting factors, while kinetic energy of particles can be classified as constraining factors.

Clogging of Infiltration Basin and Its Impact on Suspended Particles Transport in Unconfined Sand Aquifer: Insights from a Laboratory Study

A laboratory study was undertaken to investigate the physical clogging of a sand medium by injecting suspended particles (SP), with diameters ranging from 0.03 to 63.41 μm, into an infiltration basin, which was installed in a sand tank under the condition of constant head. The hydraulic conductivity (K) of the saturated porous medium was found to have decreased by 27% because of re-arrangement over the seven days of self-filtration. A clogging layer was observed on the infiltration basin bottom, probably due to straining over the stormwater infiltration stage. Particle-size analyses also indicate that retention of bigger SP led to faster straining of smaller SP, despite the small fraction of bigger SP. The clogging layer weakened the hydraulic connection between the water level in the basin and the water table of the unconfined aquifer until nearly no water could infiltrate into the aquifer. The deposition of finer SP that entered into the aquifer are governed by the hydrodynamic forces. These finer SP caused non-uniform permeability reduction of the porous medium, with an estimated 35% of permeability reduction occurring beneath the infiltration basin. However, the reduction appears to be reversible, as the fine SP deposited on the pore surfaces of the porous medium can be released or detached by the continuous horizontal hydraulic gradient. Extended tailing of the outlet breakthrough curve (BTC) also strongly supported the detachment of SP. This study focused on the effects of particles’ polydispersity and hydrodynamic forces on the hydraulic characteristics of the porous medium.

Experimental investigation of suspended particles transport in porous medium under variable temperatures

AbstractThis paper presents a study on suspended particle transport in porous medium with the aid of a sand layer transportation–deposition testing system to determine the kinetic characteristics of particles in porous medium under variable temperatures. Quartz sand and quartz powder were chosen as the porous medium and particle in the tests, respectively. Four size compositions and two operational modes, that is, temperature reduction mode (changing from 18°C to 5°C) and temperature increment mode (changing from 18°C to 35°C), were adopted. The turbidity and concentration of quartz powder were measured under various conditions. We observed a high temperature‐independent correlation between them. Breakthrough curves under different conditions were analysed using this testing system. The results showed that changes in temperature affected the particle transport process to some extent, and the degree of influence was closely related to the time moment of the temperature change onset. Moreover, we found a hysteresis phenomenon in the breakthrough curve under both temperature reduction and increment conditions. The results also indicated that the temperature effect was particularly significant for smaller particles. The typical curves to represent particle transport process under variable temperatures were put forward according to the results. To explain the test results, four factors, that is, water viscosity, adsorption effect, double layer force, and particle kinetic energy, were considered and categorized as promotion or constraining factors.

Modelling of turbidity distribution along channels

The purpose of the article is to develop the required and sufficient conditions under which numerical methods can be used for engineering calculations and for scientific research of hydrodynamic processes in solving practical problems related to surveying of pollutants diffusion in water flows. The conducted studies consisted in the finding out conditions under which mathematical modelling using hydrodynamic equations allows to solve engineering problems of channel hydrodynamics and, in particular, to numerically simulate the transport of suspended particles in channels. A number of additional nature of numerical models were studied in addition to approximation and stability, such as averaging over probability and over time averaging. It was noted that only stationary processes could be described by equations if they are obtained from the Reynolds equations, i.e. when using the Reynolds equations, an important class of problems with a pulsating flow under constant boundary conditions is excluded from consideration. And, if the equations are obtained directly from the conservation laws, then all the desired variables have the meaning of actual quantities averaged over the scale. That is even in the case of statistically stationary flows, using such equations, it is possible to solve nonstationary problems on large time scales.

Artificial Cilia for Microfluidics Particle Capture

Microorganisms use biological cilia to create various kinds of transport, and most important among them is the transport of suspended particles. Biological cilia are shown to effectively capture and trap specific particles for feeding(1–5). Motivated by this, the use of artificial magnetic cilia to capture particles suspended in a fluid is proposed. Perhaps, such nature inspired ciliary capture and isolation of particles can be incorporated in microfluidic lab on chip devices for pre-concentration of cells and analytes. In this paper, the particle capture capabilities of magnetic cilia is demonstrated.

Model of grout filtration in a porous soil

To strengthen the foundations and protect them from ground water, liquid grout is pumped under pressure into a loose porous soil. Modern construction techniques use colloids or suspensions which form a waterproof layer upon solidification. Calculation of grout distribution in a porous soil is an important part of designing buildings and structures. The distribution of suspended particulates in unconsolidated soil is described by mathematical equations of particles filtration in the porous media. The aim of this work is modelling of suspended particles transport and deposit formation in a porous soil for different filtration modes. The distributions of solid particles of different sizes transported by the carrier fluid and retained on the frame of the porous medium at different kinetic rates of deposit growth are examined. Model of one-dimensional filtration with size-exclusion particle retention mechanism includes a hyperbolic system of the first order differential equations with inconsistent initial and boundary conditions that leads to discontinuous solutions. A modified mathematical model for polydisperse media with the competition between particles of different sizes for small pores is considered. The computational scheme for numerical solutions is constructed by finite difference method. Optimization methods to improve convergence and reduce computation time are used. A multi-particle model of grout filtration in a porous soil is constructed, considering the variety of sizes of suspended particles. A numerical calculation of the problem is performed for various blocking filtration coefficient. Solutions are obtained with a discontinuity on the concentration front. Approbation of the obtained numerical solutions is carried out. Plots of the suspended and retained particles concentrations depending on time and coordinates are constructed. A new model of multi-particle transport in a porous medium widely extends the design capabilities of waterproof underground walls. The solution of the filtration problem for solid particles of different sizes makes it possible to calculate the optimal composition of grout for constructing a waterproof layer in a porous soil. The developed computing finite-difference methods allow to obtain the numerical solution of complex systems of equations with good accuracy and a moderate amount of computation.

Particle transport in a porous medium with initial deposit

Modelling of the suspended particles transport in a porous medium is used in the analysis of methods for strengthening foundations. To strengthen the porous soil, a low concentration cement-based grout is pumped into it under pressure. The suspension is filtered in a porous medium and fills the cavity of the soil. Grains of the grout are distributed along the network structure of the porous medium and strengthen the soil. The transfer of particles by a flow of a carrier fluid is accompanied by an uneven formation of a deposit on the porous medium frame.The purpose of the paper is to determine the mobile two-phase boundary between water and the particles during the injection of a suspension into a porous medium and to obtain an analytical solution of the nonlinear filtration problem for a general case of variable porosity and permeability.The mathematical model of one-dimensional deep bed filtration with size-exclusion particles retention includes the equations of mass balance and kinetic rate of a deposit and unsteady boundary conditions with unknown dimensionless concentrations of suspended and retained particles. Methods of non-linear asymptotic analysis are used to obtain the analytical solution and to construct an asymptotics near the porous medium inlet. The asymptotics is determined on the basis of a local exact solution of the problem.It is shown that the mobile two-phase boundary moves with variable speed. At the boundary of two phases, the concentration of suspended particles is discontinuous, and the concentration of retained particles is continuous and loses its smoothness. The exact explicit formula for the two-phase boundary and its asymptotics in a form convenient for calculations are obtained. An exact solution is obtained on the boundary of the porous medium and the asymptotics of the filtration problem is constructed near the porous medium inlet. Numerical calculation of the asymptotic solution is performed; graphs of the dependence of concentrations on time and coordinate are presented.In contrast to the numerical solution, analytical methods make it possible to determine the dependence of the solution of the filtration problem on the controlled external parameters. This allows the construction engineers to choose the best size of injected grout grains and the properties of the carrier fluid, optimize the filtration process and form a grouted porous soil of the required strength and density.

Validation of a low field Rheo-NMR instrument and application to shear-induced migration of suspended non-colloidal particles in Couette flow

Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1H resonance frequency of 10.7MHz), which is portable and suitable as a process monitoring tool. This system is applied to the measurement of steady-state velocity profiles of a Newtonian carrier fluid suspending neutrally-buoyant non-colloidal particles at a range of concentrations. The large particle size (diameter >200μm) in the system studied requires a wide-gap Couette geometry and the local rheology was expected to be controlled by shear-induced particle migration. The low-field results are validated against high field Rheo-NMR measurements of consistent samples at matched shear rates. Additionally, it is demonstrated that existing models for particle migration fail to adequately describe the solid volume fractions measured in these systems, highlighting the need for improvement. The low field implementation of Rheo-NMR is complementary to shear stress rheology, such that the two techniques could be combined in a single instrument.

An Experimental Setup with Radial Injection for Investigation of Transport and Deposition of Suspended Particles in Porous Media

Abstract A radial injection experimental setup is presented in this paper, which allows one to study the transport and deposition of suspended particles and permeability impairment in porous media. This setup allows one to simulate the conditions of the injection of produced water in oil reservoirs from an injection well. This is achieved by a radial injection of water containing suspended particles of a few microns in size from a central well including a sand screen, through a confined cylindrical sand pack (diameter 52 cm, height 40 cm). A peripheral drainage system permits the recovery of the fluid at the outlet of the sand pack by a collector equipped with a turbidimeter for measuring the concentration of suspended particles. The injection pressure is measured at the inlet, and six pore pressure probes have been installed at different locations inside the sand pack. First experimental results presented show a significant heterogeneity of deposited particle profiles in both radial and axial directions.

Suspended particle transport through constriction channel with Brownian motion.

It is well known that translocation events of a polymer or rod through pores or narrower parts of micro- and nanochannels have a stochastic nature due to the Brownian motion. However, it is not clear whether the objects of interest need to have a larger size than the entrance to exhibit the deviation from the dynamics of the surrounding fluid. We show by numerical analysis that the particle injection into the narrower part of the channel is affected by thermal fluctuation, where the particles have spherical symmetry and are smaller than the height of the constriction. The Péclet number (Pe) is the order parameter that governs the phenomena, which clarifies the spatio-temporal significance of Brownian motion compared to hydrodynamics. Furthermore, we find that there exists an optimal condition of Pe to attain the highest flow rate of particles relative to the dispersant fluid flow. Our finding is important in science and technology from nanopore DNA sequencers and lab-on-a-chip devices to filtration by porous materials and chromatography.

REMOTE ESTIMATION OF TOTAL SUSPENDED SOLID (TSS) TRANSPORT AFFECTED BY TIDAL BORE “BONO” OF KAMPAR BIG RIVER ESTUARY USING LANDSAT 8 OLI IMAGERY

The Kampar River estuary has a unique tidal bore, namely Bono. A tidal bore is a natural phenomenon caused by the tidal flow which meet the flow of the river. Tidal bore "Bono" has an impact on the transport of suspended particles which is pretty much along the Kampar River. The purpose of this study is to determine the estimated concentration of total suspended solid in the river as the result of the transport by Bono in Kampar River estuary by Landsat 8 OLI. The primary data are Landsat 8 OLI sensor – on Path 126 and Row 60, recording date was on 23 -04-2016, which was analyzed spatially – and TSS in situ. The secondary data are tide forecasting data and topographical map of Indonesia. Distribution of total suspended solid indicates sediment transport and its distribution by TSS values ranged between 10-150 mg.L-1 and TSS in situ value ranged between 42-241 mg.L-1. Tidal range ranged from 0.78 to 4.2 m and current velocity ranged from 0-0.9 m.s-1, which generate tidal bore extending from the mouth to the river body, resulting in suspended particle transport along the river. TSS concentration is higher in the river estuary.

Physical factors affecting the transport and deposition of particles in saturated porous media

AbstractSaturated sand box experiments were conducted to explore the effect of various physical factors on the transport and deposition of suspended particles in porous media. Red quartz powder and natural quartz sand were employed in the study and acted as suspended particles and porous media, respectively. Particles were injected into the sand box in two modes, i.e., pulse injection and continuous injection. Tests were performed at various particle concentrations, flow velocities, deposition rate coefficient and longitudinal dispersion coefficient by both injection modes. The breakthrough curves were described with the analytical solution of a convection–dispersion equation, in which first-order deposition kinetics were taken into account. Different behavior of suspended-particle transport and deposition in porous media was observed under different injection modes and experimental conditions. The results show that effluent concentration was approximately linear with the initial particle concentration. The deposition rate coefficient depends strongly on particle size and flow velocity, and the transport and deposition process was very sensitive to it. Furthermore, the longitudinal dispersion coefficient increases with increasing flow rate, and particles are easier to transport through pores as the longitudinal dispersion coefficient increases. This study shows the importance of particle concentration, flow velocity, deposition rate coefficient and longitudinal dispersion coefficient in the transport and deposition process of suspended particles.

Coupled Effects of Ionic Strength, Particle Size, and Flow Velocity on Transport and Deposition of Suspended Particles in Saturated Porous Media

In this study, the coupled effect of ionic strength, particle size, and flow velocity on transport and deposition of suspended particles (SP) in saturated sand was undertaken. Three polydispersive SP populations (silt particles with the median of 3.5, 9.5 and 18.3 \(\upmu \)m) were investigated using a pulse injection technique. High ionic strengths were used and vary from 0 to 600 mM (NaCl). Two high velocities were tested: 0.15 and 0.30 cm/s. Suspended particles recovery and deposition kinetics were strongly dependent on the solution chemistry, the hydrodynamics, and the suspended particles size, with greater deposition occurring for increasing ionic strength, lower flow velocity, and larger ratios of the median diameter of the SP to the median sand grain diameter. A shift between the extended Derjaguin–Landau–Verwey–Overbeek theory prediction (the particles and sand grain surfaces are considered chemically and topographically homogeneous) and the experimental results for certain ionic strength was observed. So, as reported in recent literature, effects of surface heterogeneities should be considered. The residence time of the non-captured particles is dependent on ionic strength and hydrodynamic. A relationship between the deposition kinetics, particle and grain sizes, flow velocity, and ionic strength is proposed.

The effect of temperature on the seepage transport of suspended particles in a porous medium

AbstractThe main purpose of this study is to experimentally investigate the effect of temperature on the seepage transport of suspended particles (SP) with a median diameter of 10–47 μm in a porous medium for various seepage velocities. The results show that the rise of temperature accelerates the irregular movements of SPs in the porous medium and reduces their migration velocity. As a result, the pore volume corresponding to the peak value of the breakthrough curves is apparently delayed, and the peak value in the effluent is decreased. The migration velocity of SPs decreases with increasing particle size, regardless of the Darcy velocity and temperature. The longitudinal dispersivity of SPs decreases slightly with increasing temperature and then remains almost unchanged. Larger particles experience more irregular movements induced by the limit of pore size, which leads to a larger dispersivity. The deposition coefficient increases with increasing temperature, especially in the case of a high seepage velocity, and then tends to be stable. The deposition coefficient for large‐sized particles is higher than that for small‐sized particles, which can be attributed to the restriction of large‐sized particles by the narrow pores in the porous medium. The recovery rate decreases slightly with the increase of temperature until a critical value is reached, beyond which it remains almost unchanged. In summary, temperature is a significant factor affecting the transport and deposition of SPs in the porous medium, and the transport parameters such as particle velocity, dispersivity, and deposition coefficient.

Porous media grain size distribution and hydrodynamic forces effects on transport and deposition of suspended particles

The effects of porous media grain size distribution on the transport and deposition of polydisperse suspended particles under different flow velocities were investigated. Selected Kaolinite particles (2–30μm) and Fluorescein (dissolved tracer) were injected in the porous media by step input injection technique. Three sands filled columns were used: Fine sand, Coarse sand, and a third sand (Mixture) obtained by mixing the two last sands in equal weight proportion. The porous media performance on the particle removal was evaluated by analysing particles breakthrough curves, hydro-dispersive parameters determined using the analytical solution of convection–dispersion equation with a first order deposition kinetics, particles deposition profiles, and particle-size distribution of the recovered and the deposited particles. The deposition kinetics and the longitudinal hydrodynamic dispersion coefficients are controlled by the porous media grain size distribution. Mixture sand is more dispersive than Fine and Coarse sands. More the uniformity coefficient of the porous medium is large, higher is the filtration efficiency. At low velocities, porous media capture all sizes of suspended particles injected with larger ones mainly captured at the entrance. A high flow velocity carries the particles deeper into the porous media, producing more gradual changes in the deposition profile. The median diameter of the deposited particles at different depth increases with flow velocity. The large grain size distribution leads to build narrow pores enhancing the deposition of the particles by straining.

Ultrafast electrokinetics.

The influence of a high electric field applied on both fluid flow and particle velocities is quantified at large Peclet numbers. The experiments involved simultaneous particle image velocimetry and flow rate measurements. These are conducted in polydimethylsiloxane channels with spherical nonconducting polystyrene particles and DI water as the background flow. The high electric field tests produced up to three orders of magnitude higher electrokinetic velocities than any previous reports. The maximum electroosmotic velocity and electrophoretic velocity measured were 3.55 and 2.3 m/s. Electrophoretic velocities are measured over the range of 100 V/cm < E < 250000 V/cm. The results are separated according to the different nonlinear theoretical models, including low and high Peclet numbers, and weak and strong concentration polarization. They show good agreement with the models. Such fast velocities could be used for flow separation, mixing, transport, control, and manipulation of suspended particles as well as microthrust generation among other applications.