Sedimentation Stability Research Articles

The influence of vibration on sedimentation stability of polymer composite materials

The work is devoted to the study of the effect of vibration on the creation of a gradient layer in cast polymer composite materials. The influence of vibration frequency and vibration exposure time on the distribution of filler particles in a polymer matrix has been studied. The presented results can be used in the manufacture of cast parts for the needs of mechanical engineering from polymer composite materials with an increased content of particles of the dispersed phase.

Application of synthetic and grafted polymeric flocculants in agricultural wastewater treatment

Due to the large amounts of freshwater consumed in Egypt by the agricultural sector that is more than 85% of Egypt share of freshwater in addition to the high concentrations of salts, chemicals and nutrients produced from fertilizers. Reduction of these pollutants concentrations to an acceptable level and breaking the sedimentation stability of colloidal substances and organic particles for reuse for irrigation purposes was associated with the application of biological treatment with coagulants addition. The flocculation process was performed by using polydiallyldimethylammonium chloride (polyDADMAC) and polyacrylamide grafted oatmeal (OAT-g-PAM). The scale-pilot consists of an aeration tank equipped with an air blower, sedimentation tank followed by a filtration stage through 20 cm of pottery scrubs media. To study the performance of synthetic and grafted polymeric flocculants, 3 trials were performed. Activated sludge process without adding any polymeric flocculants was the control trial. In the second trial, polyDADMAC was added with a dose of 5 mg/l. Finally, OAT-g-PAM with a dose of 1.25 mg/l was used in the third trial. The physicochemical properties of agricultural wastewater were measured at the national research center in Cairo. It was found that OAT-g-PAM incorporated with activated sludge process was the most effective in treating agricultural wastewater as it achieved COD, BOD,TKN, TP, and TSS removal efficiency up to 92.29%, 93.13%, 90.64%, 90.46%, and 92.5%, respectively which made it suitable to reuse for agricultural purposes, in addition to its ability to biodegrade, environmentally friendly, and low dosage required compared to polyDADMAC.

In Ukrainian

Man-caused load on sources of industrial and domestic water supply, which causes the discharge of insufficiently treated wastewater, is one of the great environmental problems in Ukraine. The traditional way of solving this problem, associated with the disposal of such waters by adsorption, membrane or catalytic technologies, has a number of disadvantages associated with large volumes and a wide range of pollutants, traditional methods often require preparatory measures, time-consuming, scarce materials and expensive equipment. It would be ideal to create waste-free circulating water supply technologies, but these options are still far from being mass-produced. A promising way to solve these problems is to organize such production cycles, where the disposal of toxic wastewater will be combined with recovery technologies. Industrial and domestic wastewater often contains a significant proportion of the organic component. These are oil products, by-products of organic synthesis, spent lubricating and cooling suspensions, waste from the food, alcohol and pulp and paper industries, dyes and pigments, etc. All this waste is energy saturated and can be separated and used as fuel. However, due to low concentrations in most wastewater, their separation is economically unprofitable. A method is proposed for neutralizing toxic organic wastewater by using it as a dispersion medium for composite coal-aqueous fuel (CAF). The possibility of priming carbon microparticles obtained by preliminary plasma-chemical treatment of an organic dispersion medium to stabilize composite coal-water fuel were investigated. Waste cutting fluid (JCL) was used as an organic dispersion medium; anthracite served as the dispersed phase. A CAF sample was obtained based on anthracite from Ukrainian deposits with a solid phase (W) content of 70 mass. %, and studied its electrokinetic and rheological properties. It has been found that the preliminary plasma-chemical conversion of organic wastewater used as a dispersion medium for composite water-coal fuel significantly improves the operational properties of CAF. The growth of sedimentation stability and the optimization of the effective viscosity are achieved mainly through the implementation of the structural and mechanical factor by increasing the number of contacts with the introduction of a highly dispersed fraction of carbon microparticles and increasing the electrostatic repulsion of the elements of the suspension structure. Thus, the sedimentation stability of the obtained CAF is significantly improved in comparison with conventional anthracite suspensions in organic wastewater and reaches 2 days without the addition of stabilizers. In the future, it is planned to further improve the properties of CAF by introducing stabilizing reagents and dispersants into its composition.

Effect of Permeability on Hydrate-Bearing Sediment Productivity and Stability in Ulleung Basin, East Sea, South Korea

Methane hydrate has attracted attention as a next-generation resource, and many researchers have conducted various studies to estimate its productivity. Numerical simulation is the optimal method for estimating methane gas productivity. Meanwhile, using a reasonable input parameter is essential for obtaining accurate numerical modeling results. Permeability is a geotechnical property that exhibits the greatest impact on productivity. The permeability of hydrate-bearing sediment varies based on the sediment pore structure and hydrate saturation. In this study, an empirical permeability model was derived from experimental data using soil specimens from the Ulleung Basin, and the model was applied in numerical analysis to evaluate the sediment gas productivity and ground stability. The gas productivity and stability of hydrate-bearing sediments were compared by applying a widely used permeability model and the proposed model to a numerical model. Additionally, a parametric study was performed to examine the effects of initial hydrate saturation on the sediment gas productivity and stability. There were significant differences in the productivity and stability analysis results according to the proposed permeability model. Therefore, it was found that for accurate numerical analysis, a regional permeability model should be applied.

Origin and evolution of tidal depressions in a tidal flat and their role in carbon sequestration in the Bahía Blanca Estuary (Argentina)

Tidal flats play an essential role in the global carbon cycle. Intertidal environments are very dynamic and have several erosive landforms such as tidal depressions (TD), although TD genesis is still poorly understood. The tidal flats of the Bahía Blanca Estuary (BBE) are ideal for TD’s study since they are hardly altered by human activity. In this site is possible to distinguish a gradation from a non- bioturbed zone to one dominated by erosive landforms. This preliminary study aims to determine the origin and evolution of TD in tidal flats and evaluate their role as carbon sinks based on an integrated sedimentological and geomorphological study. We found that the origin of TD in siliciclastic tidal flat is associated with the activity of the Neohelice granulata crabs. N. granulata selects finer particles and organic matter to build burrows; also alter the physical properties of the sediment. The loss of sediment structure by the increase in the density of excavations added to the tidal dynamics favour the burrows's collapse giving rise to the tidal depression. Tidal dynamics affect sediment stability by exerting a hydrostatic pressure on the burrow when flooding and emptying of burrows. The effect of N. granulata in the sediment record is clearly identifies by an increase water content with a decrease in the sediment density. Furthermore, it is possible to identify changes in the grain size distribution curves of the typical tidal flat facies as a second mode at 10 μm. These features can be recognised and used as a tool to identify TD in the geological record. TD with occluded crab burrows can be important organic carbon sinks due to the organic matter fixation under suitable conditions that delay its decomposition. Due to the large number of TD (of the order of 35 million), we estimated that the C sequestration by these landforms might be of the order 1.8 × 10–3 Gtn without considering that may be stored directly on the tidal flats themselves.

Lateral sediment erosion with and without the non-dense root-mat forming seagrass Enhalus acoroides

Coastal areas are at increasing risk from flooding and erosion due to coastal development and climate change. Seagrass meadows, like other coastal ecosystems, can stabilise sediments, indirectly reducing coastal erosion. There is evidence that seagrass can reduce both the erosion of seabeds and lateral erosion of seagrass cliffs. However, these previous studies have only considered seagrass species whose below-ground biomass form dense root mats. This study aimed to investigate whether Enhalus acoroides, a species which does not form root mats, reduces lateral erosion rates of seagrass cliffs. To do this, samples of E. acoroides collected in sandy sediments within Xincun Bay China were transplanted into a wave flume. Lateral erosion rates were measured under exposure to waves for five cliff heights over 1 h. There was an interaction between cliff height and time on the rate of erosion, with higher erosion rates earlier in the experiment for larger cliff heights. The cores with the E. acoroides persisted longer than unvegetated cores, regardless of cliff height, but this result was not assessed statistically due to constraints in the analyses. The below-ground biomass of E. acoroides samples in this study was higher than values previously reported in the literature. Overall, these results suggest that non-dense root-mat forming seagrass species may not provide equivalent sediment stabilisation as dense root-mat-forming species, likely due to the reduced binding structure of the roots in species such as Enhalus.

Preparation of Cellulose/Laponite Composite Particles and Their Enhanced Electrorheological Responses.

Cellulose, as a natural polymer with an abundant source, has been widely used in many fields including the electric field responsive medium that we are interested in. In this work, cellulose micron particles were applied as an electrorheological (ER) material. Because of the low ER effect of the raw cellulose, a composite particle of cellulose and Laponite was prepared via a dissolution–regeneration process. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to observe the morphologies and structures of the composite particles, which were different from pristine cellulose and Laponite, respectively. The ER performances of raw cellulose and the prepared composite were measured by an Anton Paar rotational rheometer. It was found that the ER properties of the composite were more superior to those of raw cellulose due to the flake-like shapes of the composite particles with rough surface. Moreover, the sedimentation stability of composite improves drastically, which means better suspension stability.

Current Situation and Key Parameters for Improving Wheat Quality in China.

Processing quality of winter-wheat is affected by genotype, environmental conditions, and crop husbandry practices. In the present study, a data set of 17 quality-related traits for 211 main winter-wheat varieties in China during 2006 to 2018 was extracted from China Wheat Quality Report. Analysis was carried out to evaluate the quality status and variations, to reveal correlation between quality-related traits, as well as to identify key influencing factors. Results indicated that the quality indicators of medium-gluten or medium-strong-gluten wheat varieties were acceptable, whereas those of weak- and strong-gluten wheat varieties were far below national standard, especially hardness index (HI), crude protein content (CPC), wet gluten content (WG), and water absorption for weak-gluten wheat and sedimentation value (SV), stability time (ST), and stretch area (SA) for strong-gluten wheat, respectively. Correlation analysis showed that WA, WG, development time, HI, CPC, falling number, ST, and tractility directly affected the overall quality of winter-wheat. CPC, SV, and WG in medium-gluten wheat had no significant correlation with the processing quality of noodles score, whereas gluten index significantly correlated with noodle score (P < 0.001). This implied that protein quality might play a more important role than protein quantity in determining medium-gluten wheat quality. Furthermore, analysis of variance showed that genetic characteristics (cultivars) had significant influences on the restriction indexes (SV, ST, and SA) of strong-gluten wheat, whereas genetic characteristics, environment conditions, and crop growing practices (cultivars, locations, and years) significantly affected the restriction indexes (HI, CPC, WG, and WA) of weak-gluten wheat. The results suggest that improvement of Chinese strong-gluten wheat should mainly focus on cultivating new varieties. As to weak-gluten wheat, cultivation and husbandry practices should be paid more attention to limit undesired high grain protein content.

Core-Shell Structured Magnetite-Poly(diphenylamine) Microspheres and Their Tunable Dual Response under Magnetic and Electric Fields.

Core-shell type poly(diphenylamine)-coated magnetite (Fe3O4-PDPA) microspheres were designed and adopted as a novel actively tunable smart material which is responsive under both electric and magnetic fields. Their morphology, chemical structure, crystalline structure, and thermal properties were characterized using scanning electron microscopy, transmission electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and a thermal gravimetric analyzer. Their magnetic and dielectric properties were determined using vibrating-sample magnetometer and an LCR meter, respectively. They were dispersed in silicone oil and their electrorheological (ER) and magnetorheological (MR) responses under the electric and magnetic fields, respectively, were examined. The formation of chain structure of Fe3O4-PDPA based E/MR fluid under the application of electric field or magnetic field was observed by an optical microscopy and the sedimentation stability was observed by a Turbiscan optical analyzer system. It was observed that the yield stress, ER efficiency, and leakage current density increased with an increase in the particle concentration, while the slope of the electric field-dependent yield stress decreased. Several models such as the Bingham model, Herschel-Bulkley model, and Cho-Choi-Jhon equations were used to describe the shear stress curves of the ER fluid; the curves fitted well. For the dielectric properties, the two types of ER fluids tested displayed the same relaxation time and distribution; however, the one with the higher concentration had a higher dielectric constant and polarizability. The Fe3O4-PDPA based MR fluid (10 vol %) exhibited typical MR properties. In addition, the Herschel-Bulkley model matched well with the shear stress curves under a magnetic field.

Long-term changes in a trochid gastropod population affected by biogenic sediment stability on an intertidal sandflat in regional metapopulation context

Although destabilization and stabilization of soft sediments by macro-infauna are regarded as key to understanding benthic community dynamics, how component populations are affected concurrently by both agents was poorly investigated. On an intertidal sandflat, Kyushu, Japan during 1979 − 2014 (previous study) and 2015 − 2019, monitoring was made of the populations of the filter-feeding gastropod, Umbonium moniliferum, the burrow-dwelling ghost shrimp, Neotrypaea harmandi (destabilizer), and the tube-building polychaete, Mesochaetopterus minitus (stabilizer). Results revealed that gastropod population changes were driven by an interplay of shrimp, polychaete, and the stingray, Hemitrygon akajei, foraging for shrimp by sediment excavation. The gastropod went through high abundance (1100 m−2) in 1979, extinction during 1986 − 1997, two marked recoveries with peaks in 2001 and 2009, a slight recovery in 2016, and near extinction in 2019. These changes largely followed the fluctuation in shrimp density across a threshold of 160 m−2 inhibiting gastropod recruitment. The polychaete exhibited intermittent outbreaks with peaks in 2000, 2007, and 2016, with maximum densities of 15,000 − 24,000 m−2. Sandflat topography and sedimentary variables were measured during 2015 − 2017. Sediment stabilization by polychaete aggregations at the mid-tidal zone is suggested to have boosted gastropod recruitment. Release at sea and retrieval on shore of drift cards mimicking gastropod larvae with 3- to 9-day planktonic duration was conducted in 2008 − 2009 to specify source populations sending larvae to the present population. Potential source populations were censused in 1998 and 2017 − 2018. Their recent virtual extinction appears responsible for the present population’s decline from 2011. This raises the need for metapopulation perspective to understand local dynamics.

Intertidal mussel reefs change the composition and size distribution of diatoms in the biofilm

Migrating diatoms are microscopic ecosystem engineering organisms that have functional consequences on the seascape scale by significantly contributing to the microphytobenthos biofilm. The microphytobenthos biofilm is a thin photosynthesising layer that covers the sediment on intertidal flats. It fuels the food web, increases sediment stability, and enhances the deposition of particles, providing ecosystem services to coastal communities. Here we tested the effect of another ecosystem engineering habitat, intertidal blue mussel reefs, on the composition and properties of migrating diatom communities. Small-scale reefs constructed in the intertidal mimicked and reinforced the natural pattern in diatom community composition and function that we documented in the field. The field experiment adding small reefs to the intertidal ran from 30 April to 10 June 2015 and the field samples were collected around a natural blue mussel bed on the same tidal flat on 7 October 2015 (N 53.489°, E 6.230°). Both the constructed small-scale reefs and the natural reef changed the community composition of diatoms in the biofilm by promoting higher numbers of smaller-sized cells and species. Small diatoms have higher growth and gross photosynthesis rates, indicating that this explains the higher production and chlorophyll-a concentration of the biofilm measured on natural intertidal shellfish reefs. Our results showed that shellfish reefs have a large impact on biofilm functioning. However, biofilms are also fuel for the shellfish, indicating that the two very different ecosystem engineers may facilitate coexistence on tidal flats through a positive feedback loop.

Micro analysis of riverbank sediment stability under different wetted surface conditions

Quantity of water entrapped between sediment particles imparts strength up to a limit and increases the stability of a riverbank. In the present study, this strength of the sediments has been investigated in terms of escape velocity of the sediments. Escape velocity has a considerable impact on the stability of the bank surface. Here, the “Truncated Pyramid Model (TPM)” for arrangement of the sediments has been utilized to determine escape velocity for different wetted surface conditions and inter-granular spaces. It has been found from the present investigation that irrespective of the variability in the riverbank morphology, the escape velocity attains a large value due to enhancement of the wetted surface area resulting in riverbank stability.

Effect of Compound Surfactants Modified Carbonyl Iron on Magnetorheological Fluids

As a fast-responding, intelligent, and controllable fluid material, magnetorheological fluid has drawn considerable attention. However, undesirable sedimentation severely restricts its wide application. To solve this problem, an improved strategy is proposed to prepare the magnetorheological fluid with great sedimentation stability. In this study, we used the compound surfactants to modify carbonyl iron powder and fumed silica as a thixotropic agent. At the same time, the effect of different contents of fumed silica on the rheological properties of MRF was studied. The scanning electron microscope, sedimentation, and rheological tests showed that fumed silica can significantly improve the sedimentation stability of magnetorheological fluids, and compound surfactants can increase its dispersion in magnetorheological fluids. As for the fumed silica (1.85 wt%) MR fluid, the sedimentation ratio is about 92.4% in the testing period of 58 days, indicating more excellent sedimentation stability compared to the commercial MR fluid (87.6%). When the magnetic field strength is beyond 391 kA/m, the shear stress is better than commercial magnetorheological fluid.

Effect of Selected Stabilizers and Processing Aids on the Stability of a Double Emulsion Encapsulating Bitter Gourd Extract

Effect of three variables in differing concentrations [NaCl (3-5%), polyglycerol polyricinoleate (PGPR) (2-4%) and dairy protein-polysaccharide complexes (Whey protein concentrate(WPC-80)-gum Arabic(GA) and sodium caseinate(SC)-gum Arabic in 1:2 ratio)] on the stability of W1/O/W2 emulsion matrix that was used to encapsulate bitter gourd extract was evaluated. The double emulsion matrix was characterized by apparent viscosity, zeta potential, turbidity and sedimentation stability by visual appearance. The physical parameters of the double emulsion matrix were very highly significantly (p &lt; 0.001) affected by all variables such as the concentration of salt, PGPR and complex (WPC-GA and SC-P) as well as their interactions. The double emulsions prepared with WPC-GA became unstable immediately after preparation or after one day of preparation. SC-GA stabilized double emulsions were found more stable than WPC-GA stabilized emulsions. A double emulsion containing 5% NaCl, 2% PGPR and 16.5% SC-GA were found most stable (10 days at 37°C) in comparison to other combinations used.

Synthesis and characterization of novel flake-shaped carbonyl iron and water-based magnetorheological fluids using laponite and oleic acid with enhanced sedimentation stability

In this study, micron-sized flake shaped carbonyl iron (CI) water-based MR fluids were prepared with adding laponite and oleic acid as an additive and surfactant, respectively. The MR suspensions are comprised of the fixed CI particles and water weight %, while weight % of laponite and oleic acid changes from 1 to 3 wt% and 0.5 to 1.5 wt%, respectively. The remarkable enhancement in magnetorheological properties was obtained with improved sedimentation stability for CI/water MR suspensions with the addition of laponite and oleic acid. It was found that at the lowest magnetic field strength, the higher laponite concentration is effective, while at the highest magnetic field strength, the smaller concentration was effective. It was because of the combined effect of the field-induced CI chains and the laponite clay gel network. Its storage moduli showed a stable plateau area for whole angular frequencies, suggesting distinguished solid-like behavior of the MR fluid. Finally, a novel correlation was obtained between the initial settling rate of the CI particles and magnetorheological behavior of CI/laponite/OA MR suspensions with 1 wt% laponite and 0.5 wt% oleic acid, which has less zero-field, high on-state shear stress with enhanced sedimentation stability. The prepared MR fluids are a reliable industrial application vibration-isolation, clutch, and brake.

Influence of clay-based additive on sedimentation stability of magnetorheological fluid

Sedimentation stability is one of the most important features of magnetorheological (MR) fluids. Clay-based additives are known for improving the stability of the MR fluids. This article describes the dependency of the clay-based additive concentration on the sedimentation stability and the rheological properties of MR fluids in non activated state (without magnetic field). The sedimentation was measured for two different base oil viscosities, two different carbonyl iron particle sizes, and additive concentration between 2 and 6 wt%. The measurements showed that the sedimentation rate exponentially decreases with the additive concentration, while the yield stress is rising. The measurements of rheological properties also showed the dependency of rheological properties of MR fluid with a clay-based additive on loading history. The influence of carrier fluid viscosity or particle size has a minor effect on the sedimentation in comparison with the clay-based additive. The addition of 6 wt% slows down the sedimentation by more than 3000 times compared to MR fluid without additives. The MR fluid with 4.85% of clay-based additive achieves slightly better sedimentation stability than commercial MR fluid LORD MRF122.

Preparation of a novel magnetorheological fluid for high temperatures.

Magnetorheological fluids, especially those in high-power magnetorheological devices, inevitably work at high temperatures because of the wall slip, energized coils and frictions between particles. In order to prepare a magnetorheological fluid for high temperatures, this work investigates the properties of three main components (soft magnetic particles, surfactants and base carrier fluids) for a magnetorheological fluid at high temperatures. On this basis, a novel magnetorheological fluid for high temperatures is prepared. Its sedimentation stability, viscosity and shear yield stress are investigated at high temperatures. The results show that the novel magnetorheological fluid has acceptable sedimentation, suitable viscosity and stable shear yield stress at high temperatures. The novel magnetorheological fluid for high temperatures can be applied to most magnetorheological devices, especially high-power magnetorheological devices.

ВЛИЯНИЕ МОРФОЛОГИИ, ФАЗОВОГО СОСТАВА И СОДЕРЖАНИЯ ЧАСТИЦ ОКСИДА АЛЮМИНИЯ НА РЕОЛОГИЧЕСКИЕ СВОЙСТВА ВОДНЫХ СУСПЕНЗИЙ НА ИХ ОСНОВЕ

This work investigated the chemical and phase composition of aluminum oxide powders obtained by various methods (alkoxide, codeposition, thermal and plasma-chemical). The physicomechanical, thermophysical and thermal properties of ceramic samples based on them have been determined. The effect of the nature of the aluminum oxide powder and the production process parameters on the sedimentation stability of aqueous suspensions based on them has been determined. The influence of the content of particles of aluminum oxide, buffer solution and rheological additives on the viscosity, sedimentation and aggregate stability of aqueous suspensions has been determined.

Microbially Induced Sedimentary Structures (MISS) and their Involvement in Sediment Stabilization and Formation of Gravelly Coastal Landforms (Berms, Spits and Bars) in Salman Hypersaline Lagoon, Red Sea Coast of Saudi Arabia

his study documents the occurrence of several MISS such as laminated microbial mats, biostabilized ripples, gas domes, mat folds, erosional pockets and remnants, microbial cracks, and gypsified mat chips in Salman hypersaline lagoon, north Jeddah city, Saudi Arabia. This study indicates that both microbial and physical processes are reponsible for sediments biostablization and formation of spits,

Классификация участков русла Северной Двины и Вычегды по сложности русловых процессов и условиям управления

The complexity of the control conditions for channel processes is examined by the case of the Severnaya Dvina River and its main tributary the Vychegda River, which are both the most important waterways of the European North of Russia. The developed and approved earlier methodology was applied to rank rivers in by the channel stability, the load and composition of sediments (the factor was applied for the first time to the rivers under study), water capacity, geological and geomorphological conditions of the channel formation conditions (embedded riverbeds or channels with wide floodplain), evolution of different morpho/dynamic types of channel, abundance and mode of deformations of riffles. The latter factor controls both possibility and features of regulative works when designing activities in water economics, navigation and construction. The data on the sediment amounts dredged from riverbeds to ensure the waterway functioning are demonstrated to be the integral estimation of the control conditions for channel processes.