Suspended Solid Particles Research Articles

Anionic polyacrylamide efficiency in goethite removal from aqueous solutions: goethite suspension destabilization by PAM

The main aim of the study was to investigate the anionic polyacrylamide (PAM) efficiency as a flocculant relative to goethite particles. This mineral is a toxic waste produced during hydrometallurgical processes and, as a result, poses a threat to the environment. In the experiments, the following analytical methods were applied: potentiometric titration, zeta potential and adsorption amount measurements, nitrogen adsorption/desorption isotherms, Fourier transform infrared spectroscopy, differential centrifugal sedimentation, UV/Vis spectrophotometry. The result analysis showed that polyacrylamide adsorbs on the goethite surface; however, its adsorption amount depends on the pH value. Due to the adsorbent–adsorbate electrostatic repulsion, the smallest number of macromolecules adsorbs at pH 9. The PAM adsorption affects the goethite surface charge and zeta potential values. It makes these parameters more negative. What is more regardless of pH value, the polymer addition contributes to clear aggregation of solid particles (suspension destabilization). Thus, PAM can be considered as a potential flocculant improving the goethite removal from aqueous wastes.

Thermophysical properties and stability of carbon nanostructures and metallic oxides nanofluids

A pioneer idea for increasing the thermal performance of heat transfer fluids was the use of ultrafine solid particles suspension in the basefluid. Nanofluids, synthesized by mixing solid nanometre-sized particles at low concentrations with the basefluid, were used as a new heat transfer fluid which developed a remarkable effect on the thermophysical properties and heat transfer coefficient. For any nanofluid to be usable in heat transfer applications, the main concern is its long-term stability. In this investigation, pentaethylene glycol-treated graphene nanoplatelets (PEG-GnP), pentaethylene glycol-thermally treated graphene (PEG-TGr), Al2O3 and SiO2 were synthesized. The thermophysical properties of PEG-GnP, PEG-TGr, Al2O3 and SiO2 were measured experimentally by using different devices and equipment. Dispersion stabilities of carbon-based nanofluids and metallic oxides nanofluids were observed for 30 days, and the results showed the higher dispersibility of the nanofluids in an aqueous media with very low sedimentation. Thermal conductivity, viscosity and density were increased, while specific heat decreased as mass concentration increased. The temperature effect on the nanofluids was directly proportional to their thermal conductivity and inversely to the viscosity, density and specific heat.

Characterisation of complex fluid media by an angle-scanning ultrasound diffractometer

The characterisation of complex fluid media (particles in liquids) by ultrasound can provide information on the particle size distribution, concentration, and aggregation of the particles. In the Rayleigh scattering regime, systems of liquid particles are dominated by monopole scatter (potentially producing thermal waves), whereas solid particle suspensions are dominated by dipole scatter (producing shear waves); thus the angular dependence of the diffracted field is expected to be different in these cases. Since mode conversion mechanisms are affected by the proximity of particles and thus by the degree of aggregation, the effect of particle type and degree of aggregation is expected to be observed in the angle-dependent signals. We report an experimental investigation of the angle- and frequency-dependent diffracted signal from cylindrical samples (in tubing) of emulsions and suspensions. The experimental results are compared with theoretical predictions using effective homogeneous properties for the complex fluids derived from multiple scattering models. We identify the differences in the diffracted signals for complex media in which the scattering mechanisms are monopole or dipole-dominated.

Nitrogen and Phosphorous Adsorption Characteristics of Suspended Solids Input into a Drinking Water Reservoir via Typhoon Heavy Rainfall

During typhoon "Mujigae" in October 2015, water samples and surface sediments were collected from Gaozhou Reservoir, a drinking water reservoir, for simulation and analysis of the kinetics of suspended solids adsorption to nitrogen and phosphorus and the adsorption isotherms of suspended solids with different particle sizes and different concentrations. The results showed no obvious nitrogen adsorption of suspended solids of Gaozhou Reservoir. However, the adsorption effect to phosphorus by suspended solids was significant and the equilibrium time of phosphorus adsorption was 10 hours. The adsorption capacity of phosphorus increased with the decrease of sediment particle size when particle sizes were less than 0.25 mm, whereas it increased with the increase of suspended solids concentration when the concentration was in the range of 0.2-2.0 kg·m-3. The adsorption isotherm of suspended solids to phosphorus conformed to the Langmuir and Freundlich models, and the maximum adsorption capacity increased with the decrease of suspended solids particle sizes, which increased with the increase of suspended solids concentrations. The maximum adsorption capacity of suspended solids to phosphorus was 0.073-1.776 mg·g-1. These results indicated that the increase of suspended solids concentration due to the heavy rainfall of the typhoon promoted the adsorption of suspended solids to phosphorus, which reduced eutrophication in Gaozhou Reservoir.

A review on the research status and development trend of equipment in water treatment processes of recirculating aquaculture systems

AbstractRecirculating aquaculture systems (RASs) are intensive aquaculture facilities models that depend on diverse water treatment equipment to maintain good water quality and produce safe and healthy high‐quality aquatic products. This article combines the main farming‐mode of water purification recirculating processes with recent cultivation‐mode scientific research and the current development of the recirculating aquaculture industry. Harmful substances are present in aquaculture wastewater due to large quantities of residual particulate matter such as residual feed, faeces and small suspended solid particles, as well as ammonia, nitrite, bacteria and carbon dioxide (CO2), in the water. These harmful substances seriously affect the quality of aquatic products, so water treatment equipment is needed to remove these substances, add oxygen (O2) to the water and adjust the temperature of the water to ensure a high‐quality environment for fish survival. This article reviews the equipment for physical filtration (e.g. solid–liquid separation equipment, microscreen drum filter and foam fractionator) that could remove suspended solids during the water treatment of RASs and the equipment for biological filtration (e.g. fluidized sand biofilter (FSB), moving‐bed biofilm reactor (MBBR) and rotating biological contactor (RBC)) that could remove ammonia nitrogen, nitrite and other hazardous substances from wastewater, as well as equipment for water disinfection and sterilization, O2 addition, CO2 removal and temperature control. Comprehensive analysis and discussion of water treatment efficiency are provided for reference to create efficient high‐end recirculation aquaculture models and increase the precision and intelligence degree of recirculating water treatment technologies in the future.

Clogging of saturated porous media by silt‐sized suspended solids under varying physical conditions during managed aquifer recharge

AbstractManaged aquifer recharge is an effective method for utilizing excess flood flows, but clogging of porous media is a limiting factor in the implementation of this water storage technique. In recent years, much research on the physical clogging of porous media during artificial recharge has been conducted. However, the understanding of clogging due to silt‐sized suspended solids (SS) is still inadequate, especially under varying physical conditions. Here, we subjected sand columns to controlled rates of flow and SS suspensions to investigate the influence of media size, SS size, SS concentration, and flow velocity on the clogging of porous media by silt‐sized SS. The results show that the diameter ratio of SS particles to sand grains is the dominant factor influencing the position of physical clogging. As pore velocity increased, the mobility of silt‐sized SS was enhanced and retention in the porous media decreased noticeably. The spatial retention profiles in the porous media were found to vary greatly at different flow velocities. The SS concentration of the infiltrating suspension also dramatically influenced the mobility and deposition of silt‐sized SS particles, such that high concentrations accelerated the clogging process. As the different physical factors changed, the breakthrough curves and retention profiles of silt‐sized SS particles changed obviously and the mechanisms of retention differed. On the whole, clogging position is mainly determined by particle size ratio, but clogging rate is dominated by a variety of factors including particle size ratio, SS concentration, and flow velocity.

Calculation of colloids filtration in a porous medium

Construction of underground storage facilities for hazardous radioactive waste requires soil grouting to prevent the penetration of groundwater. Modern technologies of grouting use a liquid-type colloidal silica grout which is injected in a porous soil and forms a protective waterproof layer after solidification. Colloids filtration in a porous medium is an important problem of underground hydromechanics.The purpose of the study is the numerical solution of the filtration problem of suspensions and colloids in a porous medium. A fluid with fine particles is injected into an empty porous medium. Suspended particles are transported by the fluid flow in a porous medium and partially get stuck in the pores. Calculation of the suspended and retained particles concentrations, depending on time and coordinate, is the theoretical basis of the soil grouting technology.The one-dimensional problem of deep bed filtration with suspended solid particles in a porous medium for variable porosity and permeability is solved by modified finite difference methods. The use of standard methods for solving the problem is impossible because of the solution discontinuity on the mobile boundary of two-phases. To calculate the global solution near the line of discontinuity and away from it, the counter-current scheme, the Lax-Wendroff scheme and the Total Variation Diminishing finite difference scheme are used. To eliminate the effects of dissipation and dispersion in the TVD-scheme various functions-delimiters are used.The result of this work is the numerical solution of the nonlinear filtration problem in a porous medium with size-exclusion mechanism of particles retention. The curvilinear two-phase boundary is calculated. A comparison of obtained numerical solutions using different methods of constructing difference schemes is provided. The graphs of suspended particles concentrations are constructed in dependence on time and coordinates.The comparison of the numerical solutions obtained by different finite-difference methods makes it possible to choose the best way for solving the filtration problem. The counter-current scheme strongly smoothes out the solution on the line of fracture. Using a non-monotonic Lax-Wendroff scheme, a solution with unnatural oscillations near the two-phase boundary is obtained. To calculate the filtration problem, TVD-schemes are the most acceptable. The best result is obtained when using the TVD-scheme with the function-delimiter min2.

Complementary methods for the determination of the just-suspended speed and suspension state in a viscous solid–liquid mixing system

A poor understanding of mixing dynamics may lead to major economic losses in numerous industries due to poor yields and waste of raw materials. Then processes can be optimized through a better understanding of solid–liquid mixing dynamics.Previous studies have characterized the suspension of solid particles in a viscous medium using a standard high shear impeller (a pitched-blade turbine or PBT) and have measured the fraction of suspended particles using the pressure gauge technique (PGT). Since the PGT cannot be applied in a straightforward way to close-clearance impellers, we developed a novel technique based on the PGT to determine the fraction of suspended particles in a system using a close-clearance impeller such as a double helical ribbon (DHR).We studied a solid–liquid suspension in the laminar and transitional regimes with high particle loadings and a DHR. Since the dynamic pressure cannot be subtracted from the total pressure determined by the PGT, we developed two alternative methods. The first was the pressure difference method, which we used to determine a range of speeds where Njs is located. The second was the sedimentation-based method which we used to accurately quantify Njs and effectively eliminate the dynamic pressure. Their pertinence and applicability were demonstrated.

Effect of Hydrazine on Redistribution of Corrosion Product Deposits in the Primary Circuit of a Shutdown Reactor in Propulsion-Type Nuclear Power Plants

A redistribution process of corrosion product (CP) deposits in the primary circuit of nuclear power plants (NPP) with propulsion service is examined. It is demonstrated that, after a shutdown of the NPP, the activity of activated corrosion products (ACP) and the concentration of stable corrosion products in the coolant increase considerably due to their entering the coolant from the deposits on surfaces of the primary circuit equipment. The corrosion products enter the coolant principally in the form of insoluble compounds, and the suspended solid particles above 0.4 μm in size account for a minimum of 90% of the total content of CPs in the coolant. This increases the CP concentration in the coolant by a factor of approximately 10, and the total activity of ACPs becomes more than 300 times the initial value determined during reactor operation. It was established that injection of hydrazine facilitated redistribution of the corrosion products and radionuclides associated with them between the surface of construction materials and the coolant: the corrosion products went into the coolant and the rate of their redeposition decreased by a factor of ten. This enables us to increase the fraction of highly active ACPs removed from the circuit by the normal cleaning system. In addition, a shift in the equilibrium on injection of hydrazine gives a higher activity of ACPs in the coolant after completion of the deposition process and removal of CPs that entered the circuit in the normal treatment system. The equilibrium activity of ACPs is approximately ten times the value specific for the installation that is cooled down without introduction of hydrazine. A decrease in this characteristic to stable low values is observed only after the reactor is put into operation.

Novel and green processes for citrus peel extract: a natural solvent to source of carbon

Annual worldwide production of citrus fruits is estimated to be more than 120 MT, out of which nearly 50% is waste in terms of citrus peel. Although orange peel waste is further processed to yield valuable chemicals such as limonene and pectin, the processes involved are highly energy consuming and uneconomical and, therefore, have limited industrial acceptability. Here, we present cost-effective, low-energy, novel and green approaches to directly use the extract of citrus fruit’s peel as print transfer medium, solvent for recycling polystyrene waste and natural polymers. Furthermore, the fine solid suspended particles in the middle layer of the extract also find their use as a source of glassy carbon upon pyrolysis. This work may be an exemplary way of green engineering to use the waste as resource for environmental sustainability.

Modeling of Sedimentation Process in Water

Sedimentation process occurs in container of water reservoir. In the sedimentation process will be observed how the fluid flow occurs and how sedimentation occurs in water. The sedimentation is influenced by the density of the water type and the speed of water in the container of water reservoir. This study aims to find out how to model the mixture of solid and liquid particles (suspension) on the container of water by way of modeling it into a mathematical form that is by using differential equations. In this case, the factors affecting the distribution of the sludge concentration will be used as a reference for modeling the mathematical equations will then be solved using differential equations. The results of this study will show that the equation model of mixed solid and liquid particles (suspension), which then is called the momentum transport equation.

Self-Assembly of Colloidal Particles

Colloidal dispersions are suspensions of micron-sized solid particles in a solvent like water or oil. Self-assembly is a widely used approach to create ordered structures of colloidal particles by engineering the inter-colloid potential. This article illustrates how entropy drives disorder to order transitions in a colloidal assembly.

A thermodynamic model of nanofluid viscosity based on a generalized Maxwell-type constitutive equation

An original study of nanofluid viscosity is proposed. The carrier fluid is assumed Newtonian but the two-phase nanofluid displays properties abiding by a generalized Maxwell constitutive law. Our approach is based on an extension of Einstein's model describing suspensions of solid particles in fluids by the introduction of the following elements: presence of a layer around the nanoparticles and a thermodynamic description of the role of size effects. The theoretical formalism is applied to liquid argon with lithium nanoparticles and to alumina nanoparticles in water. Good agreement with experimental data and molecular dynamics simulation is observed.

Collective dynamics in dispersions of anisometric pigment particles

Dynamics of suspensions of solid rodlike pigment particles in a non-polar solvent were studied in a concentration range from the isotropic up to the orientationally ordered nematic-like phase. Using dynamic light scattering and gradient recovery measurements, we studied the rotational and translational diffusion coefficients. We demonstrate that the translational diffusion coefficient in this system is increasing with increasing concentration of the pigment particles in the vicinity of the transition into an ordered phase. This unexpected behaviour can be attributed to the collective interactions between the particles and the alignment effects.

Mathematical and Numerical Modeling of the Suspension of Particles Due to the Air Flow Between Two Rigid Walls

The main objective of this research was to study the suspension of particles in a turbulent flow (k-e model) of a Newtonian fluid between two rigid walls. The mathematical study is presented by Navier-Stokes equations and equation of transport of the particles. In order to study the effect of the fluctuations, the decomposition of Reynolds was applied to all the equations previously established. The approach of the phenomenon is made using mathematical and numerical way by using the finite volume method as a method of discretization, and the Gauss-Seidel method as a method of solution. This is to establish a numerical code, using the FORTRAN language, which makes it possible to solve the equations and to determine the particle’s concentration profile c, and the fluid velocities u, w respectively in Cartesian coordinate. The work carried out concerns the understanding and the modeling of the mechanisms of suspension of solid particles in a fluid flow.

Herbicidal and Seed Dormancy Induction Activity of Fermentation Residual Vinasse

AbstractVinasse, a liquid fermentation residual of bio-ethanol production that also contains solid particles in suspension, is commonly used as a soil amendment. Previous studies reported vinasse reduced seed germination and seedling establishment, suggesting herbicidal activity. Laboratory experiments were conducted to determine whether vinasse herbicidal activity is present in the liquid or solid phase, and whether it affects plants during seed early germination (i.e., imbibition), late germination (i.e., embryo growth and radicle protrusion), or seedling growth. Most of the herbicidal activity was associated with the liquid phase, and for most species, seed viability was predominantly affected after the imbibition phase. Susceptibility to vinasse was species dependent. Lettuce (Lactuca sativaL.) germination was <8% when seeds were imbibed and germinated in vinasse solutions or imbibed in water and germinated in vinasse. Conversely, imbibing lettuce seeds in vinasse solutions and germinating them in water did not change their germination in comparison with seeds imbibed and germinated in water (>80% germination). Wheat (Triticum aestivumL.) and sicklepod [Senna obtusifolia(L.) H. S. Irwin & Barneby] germination decreased 10% and 35% when seeds were imbibed and germinated in vinasse, respectively, while Palmer amaranth (Amaranthus palmeriS. Watson) and southern crabgrass [Digitaria ciliaris(Retz.) Koeler] germination decreased >90%. All evaluated species reduced radicle growth as vinasse concentration increased. Filtered liquid vinasse with reduced concentration of salt and ionic compounds inhibited radicle growth similarly to unfiltered vinasse, indicating that the herbicidal activity was not due to osmotic effects and was likely present in the organic liquid phase.Amaranthus palmeri,S. obtusifolia, andD. ciliarisincreased the proportion of dormant seed more than 2-fold when they were imbibed or imbibed and germinated in vinasse solutions. Vinasse might be useful for weed management to reduce germinable weed seedbanks by increasing seedling mortality and seed dormancy either by properly timing of its application as a soil amendment or by purifying herbicidal compounds and using them directly for weed control.

Improvement in filtration properties of water-based drilling fluid by nanocarboxymethyl cellulose/polystyrene core\u2013shell nanocomposite

Since almost all drilling problems directly or indirectly relate to drilling fluid, improvement in drilling fluid significantly enhances drilling operations. Drilling fluid contains base fluid, suspended solid particles and chemicals. Recently, nanoparticles have been widely recommended for improvement in drilling fluid properties. The main purpose of this study was to improve the rheological and filtration properties of water-based drilling fluid through adding new additive carboxyl methyl cellulose (CMC)/polystyrene core–shell nanocomposite. It compares filtration and rheological behavior of CMC, nanoCMC and core–shell nanocomposite. The core–shell nanocomposite was synthesized by miniemulsion polymerization method, and nanoCMC and core–shell nanocomposite were characterized by scanning electron microscope, transmission electron microscopy, particle size analyzer and thermogravimetric analysis. Fluid loss, mud cake thickness, viscosity, weight and pH of drilling fluid with core–shell nanocomposite additive were compared with conventional CMC (bulk CMC) and nanoCMC particles. Results showed a significant decrease in mud cake thickness and fluid loss when the core–shell nanocomposite was used, as compared with conventional CMC and nanoCMC. Viscosity of three additives has same trend with insignificant change while less yield point is obtained for drilling fluid containing core–shell nanocomposites. Mud weight and pH were almost the same for all three additives. Thus, the core–shell nanocomposite can be an alternative additive to control mud cake thickness and fluid loss while maintaining other main properties in an acceptable range.

Wpływ pokrycia dachu na ilość i wielkość zawiesin w spływach deszczowych

Among various drainage surfaces which allow rainwater to be utilised locally, roofs are frequently chosen solution. This is because they represent a big share of all sealed surfaces in cities and discharged liquids are considered potentially clean. Scientific reports confirm that pollutants accumulate on roofs and influence the quality of discharged water. Suspended solids are the biggest group of pollutants which occur in runoffs. The selection of rainwater pre-treatment installation and further use of the water depends on the concentration of suspended solids and their particle size. This article describes results of a research concerning suspended solids discharged from roofs made of traditional materials as well as green-roofs located in urban areas. The quantity and size of particles were assessed against rainfall characteristics: rainfall depth, length of antecedent dry weather periods and season. Results of the research show diversity of concentration levels and size of suspended solids within runoffs in reference to roofing materials, rainfall characteristics and season. The highest concentrations of suspended solids in runoff from traditional roofs were observed during rainfall depth less than 5 mm, after ancedent dry weather periods more than 50 h and in winter. These parameters did not have significantly influence on the low concentrations of suspended solids in runoff from green roofs. Suspended solids particles with the size of up to 200 μm constitute the biggest share of all roof runoffs.

How does temperature govern mechanisms of starch changes during extrusion?

Potato and pea starches were processed on a twin-screw extruder under various moisture and thermomechanical conditions, chosen to keep material temperature Te close to starch melting temperature, Tm, whilst avoiding die expansion. Extruded rods were analysed by asymmetrical flow field flow fractionation coupled with light scattering, X-ray diffraction, DSC, and light microscopy with image analysis. Molar mass of extruded materials decreased more for potato than for pea starch, when specific mechanical energy SME increased, likely because of larger amylopectin sensitivity to shear. No crystallinity was detected when ΔT = (Tm-Te) ≤ 0. Residual gelatinization enthalpy ΔHg decreased with ΔT. As illustrated by larger ΔT values for ΔHg = 0, decreasing moisture favored melting, likely by increasing solid friction. The fraction of granular remnants of potato starch was inversely correlated to SME. These results could be explained by considering starch melting during extrusion as a suspension of solid particles embedded in a continuous amorphous matrix.

Flow Patterns Induced by the Thermocapillary Effect and Resultant Structures of Suspended Particles in a Hanging Droplet.

We focus on the flow patterns and resultant structures of suspended solid particles in a hanging droplet caused by the thermocapillary effect. A droplet is hung on a heated cylindrical rod facing downward, and another cooled rod is placed just beneath the droplet to create the temperature difference between both ends of the droplet. As the temperature difference increases, the induced flow exhibits transitions from an axisymmetric time-independent steady state to three-dimensional time-dependent oscillatory states. These flow states are judged through detecting spatiotemporal correlations between the behaviors of the particles and the variation of the temperature over the droplet surface. We find that the particle accumulation structures are realized in this geometry and that their structures vary as a function of the intensity of the thermocapillary effect.