Medium Sand Research Articles

Geotextile filtration characteristics in piping rescue under extreme soil-retained state

Geotextiles have significant potential in rescuing backward erosion piping (BEP) occurring in levees. To investigate the filtration characteristics of woven geotextile for BEP prevention under the extreme soil-retention state, laboratory experiments were conducted using woven geotextiles with different pore sizes. The extreme soil-retention characteristics of the geotextile were analyzed, and the optimal relationship between filter pore size and particle size of the protected soil was explored. Additionally, the impact of fine particle content of the protected soil on the filter’s filtration performance was studied. The results indicated that, for the medium sand and silty sand tested, the filter still met soil retention requirements when the ratio of the geotextile’s equivalent pore size (O95) to the protected soil’s characteristic particle size (d85) was 5.2 and 4.3, respectively. With the increase of filter pore size, the clogging degree of the filter showed a trend of rapid decrease followed by an increase, indicating that there was an optimal matching relationship between the filter aperture and the particle size of protected soil. When woven geotextiles are used for preventing BEP, to ensure optimal filtration performance of the filter, the recommended values for O95/d85 in medium sand and silty sand are 5.2 and 3.3, respectively.

Stormwater runoff volume reduction and pollutant removal efficiency via bioretention cell using rock wool as the media

ABSTRACT Bioretention cells have been widely used in stormwater management. Media plays an important role in stormwater runoff reduction and pollutant removal. A novel bioretention media of rock wool has been proposed, and its effect on stormwater runoff reduction was investigated via a laboratory-scale experiment. The results showed that compared with the conventional bioretention (CB) using medium sand as media, the volume capture ratio of annual rainfall (VCRAR) of the rock wool bioretention (RWB) was 2.66–5.5% higher, and the peak flow reduction rate was 2.97–11.32% higher. The removal efficiency rates of the RWB on COD, NH4+ -N, TN, and TP were 25–30%, 10–31%, 20–40%, and 5–14% higher than the CB, respectively. The removal efficiency of the RWB on botht Pb and Zn was >99%. The microbial high-throughput sequencing results showed that the RWB can provide a better breeding environment for Bacteroides and Actinobacteria, which is conducive for the removal of pollutants. The RWB had a better stormwater runoff volume reduction rate and pollutant removal efficiency than the CB, therefore, it could be used as a better media for bioretention cells to improve stormwater management efficiency by using rock wool, obtained from construction waste, as the media.

The influence of soil factors on the different vegetation formations of the Dunas Park, Salvador, Bahia, Brazil

This article was conducted in a restinga ecosystem on quaternary sandy deposits of Parque das Dunas, Salvador, Bahia, Brazil; located north of Salvador, this area comprises a landscape formed by different edaphic gradients with varied vegetation formations. An edaphic characterization of the sections of these remnants was carried out to understand the influence of edaphic factors on the distribution of the plant composition of this environment. For this purpose, a transect was delimited perpendicular to the coastline. In this transect, 08 plots of 25x25m were implanted, 100m apart. In the Centre of each plot, a 1m wide and 60 cm deep trench was opened, where soil samples were collected to determine edaphic and granulometric parameters. These samples in each plot followed the distribution of the vegetation formations of this environment. It was found that the different water regimes and topography of the area influence the soil factors, which interferes with the distribution and heterogeneity of the vegetation. The highest levels of fine, very fine and medium sand fractions and calcium and phosphorus were found in the highest portions. These areas, with better drainage, have a higher plant density. There is a lower vegetation density with open sandbanks in lower areas, lower levels of fine, very fine and medium sand fractions, and lower nutrient retention. In these environments, some areas are partially flooded with adapted species. It was also found that most of the plots had a very acidic pH with the presence of exchangeable Al, which could indicate high nutrient unavailability. Thus, the sandbanks' soil conditions influence the vegetation's development, inducing the plant species to develop adaptive mechanisms to maintain their biological organization.

CFD-DEM study on the blocking conformation of pre-filled sand control screen by layering method

Preventing screen blockage due to sand poses a significant challenge. The article combines computational fluid dynamics (CFD) and discrete element method (DEM) to establish a fully coupled four-way interaction model. A sophisticated size particle injection model was established, taking into account the particle size distribution (PSD) characteristics of the formation. A layering method was used to study the sand control behavior of a high-performance pre-filled screen. The study also quantitatively investigated the impact of factors such as median sand size (D50), screen structure, and fluid velocity on both wellbore-screen annulus and internal screen plugging patterns. The findings reveal that the sand retention rate within the wellbore-screen annulus exceeds 93.8 %. The risk of pre-filled screen blockage is minimized when the ratio of gravel diameter to sand diameter falls within the range of 3.3–5. At a gravel filling rate of 97 %, fine sand predominantly moves radially, resulting in a low risk of blockage at the screen's entrance layer, thereby favoring oil and gas production. In cases with elevated fine sand content, it is advisable to maintain a production flow rate below 3 m/s to mitigate localized erosion damage caused by increased pressure resulting from screen blockage. This model holds significant importance in optimizing completion tools and production parameters.

Characterisation and Spatial Distribution of Sediments on the Cote d'Ivoire Continental Shelf (Abidjan to Assinie)

The continental shelf of Côte d'Ivoire, particularly the Abidjan-Assinie area, has been studied due to its importance and potential, although little research has focused on its sedimentological aspects. Sediment samples were collected using a Shipeck grab, and grain size analyses revealed the presence of fine sands, medium sands, and rarely very fine sands. These sands exhibit a skewness toward finer grains, which is abundant, followed by nearly symmetrical and highly skewed towards finer grains, describing five (05) types of sorting. Deposited in a more or less turbulent environment or due to excess load, the sands have been transported in water — as indicated by their shiny, abraded state — by saltation, suspension, and mixed modes. These sands preferentially reside in a continental domain.

Modulating the Rhizosphere Medium and Indole − 3−butyric Acid Supply Influence Rooting, Nutrients and Biochemical Constituents and Histological Features of Pedilanthus tithymaloids

AbstractPedilanthus tithymaloids is a popular temperate indoor succulent ornamental plant and is highly marketable. However, the appropriate propagation techniques should be adopted to solve the rooting issues of cuttings. Therefore, the present research was designed to specify the optimal indole − 3−butyric acid (IBA) concentration and rooting medium type for obtaining good rooting and healthy plants. Three IBA levels (0, 1.0, 2.0, and 3.0 g L− 1) and five growing mediums (sand, sand: clay, sand: peat moss, sand: perlite, and sand: vermiculite as 1:1, v/v) were used. The experiment was performed in a randomized complete block design in three replications. The obtained data illustrated that roots number per cutting and rooting percentage reached the maximum values by treating P. tithymaloids cuttings with 3.0 g L− 1 IBA x sand: perlite or sand: vermiculite medium. Cultivating the treated-IBA 3.0 g L− 1 cuttings of P. tithymaloids in sand: perlite showed the most enhancements in plant height, branches number and leaves number, leaf area and herb dry weight. However, the heaviest root dry weight was noticed with IBA 3.0 g L− 1 x sand: peat moss medium. Except sand medium, all other tested media in combination with IBA at 1.0, 2.0–3.0 g L− 1 showed remarkable stimulation effect on chlorophyll content. Sand: vermiculite mixture x IBA at 2.0 g L− 1 was the effective practice for improving carbohydrates percentage. By studying the anatomical changes of the adventitious root of P. tithymaloids plant, it was found that there was an increase in the root diameter, phloem and xylem tissues and xylem vessels diameter due to growing in sand: perlite x 3.0 g L− 1 IBA. In conclusion, dipping the cuttings bases of P. tithymaloids in 3.0 g L− 1 IBA and cultivation in sand: perlite considered the most effective combination practice for better rooting ability and growth and could be advisable for commercial production.

Effect of Different Growing Media and Polybag Sizes on Seeds Germination & Root System of Rough Lemon (Citrus jambhiri Lush.) in Nursery Condition

Aims: The study aimed to evaluate the different growing media & polybag size for seedling growth of rough lemon rootstock. Study Design: The experiment used a Complete Randomized Design (CRD) with three replications. Place and Duration of Study: The study "Effect of Growing Media and Polybag Size on Rough Lemon Seedling Growth" took place in an insect-proof net house at CCS Haryana Agricultural University during the 2021-2022 academic year. Methodology: It comprising of 30 treatment combination i.e., ten different growing media: T1: garden soil; T2: soil: sand (1:1); T3: soil: sand: leafmold (1:1:1); T4: soil: cocopeat (1:1); T5: sand: cocopeat (1:1); T6: soil: sand: cocopeat (1:1:1); T7: soil: FYM (1:1); T8: sand: FYM (1:1); T9: soil: sand: FYM (1:1:1); T10: soil: sand: FYM: cocopeat (1:1:1:1), and the polybags S1: large (30 x 18 cm), S2: medium (21 x 18 cm) & S3: small size (17 x 16 cm) bags. Results: The study found that adding cocopeat to growing media (T4, T5, T6) resulted in earlier germination and higher rates (87-89%) Whereas, T4 to T10 media consists of either FYM, cocopeat for both resulted into more germination 87-89% as compared to controls (T1, T2, T3). The most of the root growth parameters i.e., diameter of tap root(2.45mm), fresh root weight (4.63g) & dry root weight (1.21g) & root: shoot ratio (0.61) improved with the media sand: FYM, soil: FYM, sand: soil: FYM, sand: soil: FYM: cocopeat in equal proportion. However, when media supplemented with cocopeat (T4, T5 & T6 ) also showed appreciable results as compared to soil, sand: soil & soil: sand: leafmold. However, sand: FYM, sand: cocopeat treatments were best in respect of number of primary roots (61.22), root volume (6.44ml). Whereas, sand: soil showed very poor results in all growth aspects. Among polybags sizes, large size (30 x 18cm) bags performed best in most of the germination & root growth parameters. Conclusion: Media enriched with organic matter outperformed sole media across all parameters, while larger polybags produced significantly better results than medium and small sizes.

Continuous oxidation of organic contaminates in soil by polylactic acid-coated KMnO4

Potassium permanganate (KMnO4), as a versatile and safe solid source of MnO4-, received substantial attention from researchers as a potential soil oxidant reagent. In this study, we prepared polylactic acid (PLA)-coated KMnO4 (KMnO4@PLA) to control MnO4- release. The experimental results indicated that the optimal preparation scheme for KMnO4@PLA was a particle size of 1–2 mm, a solid-liquid ratio of 1:3, and a core-shell ratio of 1:3. And the release lifetimes of MnO4- from KMnO4@PLA in aqueous and quartz sand media were 200 hours and 310 hours, respectively, which were 2400 and 33 times longer than the release lifetimes of raw KMnO4. The controlled release of MnO4- from KMnO4@PLA was achieved through the hydrolysis of PLA. And the release process adhered to first-order reaction kinetics and displayed Fickian diffusion characteristics. Moreover, the removal of phenol by KMnO4@PLA in aqueous, quartz sand, and soil media were investigated through batch and flow column experiments. Compared with the raw KMnO4, the KMnO4@PLA exhibited a stronger ability to degrade phenol, due to the mildly acidic nature of the PLA shell. These findings demonstrated that KMnO4@PLA has significant advantages for the remediation of organically contaminated soils.

Efficiency of Backwashing in Removing Solids from Sand Media Filters for Drip Irrigation Systems

Sand media filters are especially recommended to prevent emitter clogging with loaded irrigation waters, but their performances rely on backwashing. Despite backwashing being a basic procedure needed to restore the initial filtration capacity, there is a lack of information about the solid removal efficiency along the media bed depth. An experimental filter with a 200 mm silica sand bed height was used to assess the effect of two operation velocities (30/45 and 60/75 (filtration/backwashing) m h−1) and two clogging particles (inorganic sand dust and organic from a reclaimed effluent) on the efficiency of backwashing for removing the total suspended solids retained in different media bed slices. The average solid removal backwashing efficiency was greater with organic particles (78%) than with inorganic ones (64%), reaching its maximum at a 5–15 mm bed depth. A higher operation velocity increased the solid removal efficiency by 16%, using organic particles, but no significant differences were observed with inorganic particles. The removal efficiencies across the media bed were more uniform with organic particles (63–89%) than with inorganic (40–85%), which makes it not advisable to reduce the media height when reclaimed effluents are used. This study may contribute to future improvements in sand media filter design and management.

Sediment sorting within a relatively wave-exposed and sandy subtidal seagrass (Zostera marina) meadow

Seagrasses impact on sedimentary intertidal and subtidal ecosystems by affecting local hydrodynamics, geomorphology and sediment properties. Their influence on hydrodynamics is to reduce flow velocities in their canopies, and this leads to increased net sedimentation rates and reduction of the grain size. Most investigations of the seagrass-hydrodynamics-sediment feedback system has been carried out over silt and fine-sand beds under tide-dominated conditions, mostly in the intertidal zone. Here, we use sedimentological data from a relatively wave-exposed and subtidal seagrass (Zostera marina) meadow in the Isles of Scilly with a fine-to-medium sand bed and show that the sand within the seagrass meadow is indeed finer than in adjacent, unvegetated regions. However, in contrast to previous studies, this is not due to increased mud/silt content within the seagrass meadow, but an almost 0.1-mm shift in the median sediment size across the sand fraction from 0.25 mm (fine to medium sand) to 0.35 mm (medium sand). The studied seagrass meadow is characterised by a distinct spatial structure comprising of vegetated ‘ridges’ and bare sand ‘valleys’. Even the bare sand valleys within the seagrass meadow are characterised by significantly coarser sand than the adjacent vegetated ridges, providing further confirmation of the efficiency of sediment sorting by wave processes that takes place within seagrass meadows. It is concluded that any numerical modelling involving sediment transport processes associated with seagrass environments must account for variability in the textural characteristics.

Fate and transport of fragmented and spherical microplastics in saturated gravel and quartz sand.

Microplastics in urban runoff undergo rapid fragmentation and accumulate in the soil, potentially endangering shallow groundwater. To improve the understanding of microplastic transport in groundwater, column experiments were performed to compare the transport behavior of fragmented microplastics (FMPs ∼1-µm diameter) and spherical microplastics (SMPs ∼1-, 10-, and 20-µm diameter) in natural gravel (medium and fine) and quartz sand (coarse and medium). Polystyrene microspheres were physically abraded with glass beads to mimic the rapid fragmentation process. The experiments were conducted at a constant flow rate of 1.50 m day-1 by injecting two pore volumes of SMPs and FMPs. Key findings indicate that SMPs showed higher breakthrough, compared to FMPs in natural gravel, possibly due to size exclusion of the larger SMPs. Interestingly, FMPs exhibited higher breakthrough in quartz sand, likely due to tumbling and their tendency to align with flow paths, while both sizes (larger and smaller relative to FMPs) of SMPs exhibited higher removal in quartz sand. Therefore, an effect due to shape and size was observed.

Pemanfaatan Media Pasir Untuk Meningkatkan Kemampuan Menulis Anak Usia 5-6 Tahun

This research aims to improve the pre-writing skills of early childhood by using sand media. The research method used is the classroom action research (PTK) method which is carried out in stages, namely planning, taking action, observing and analyzing or reflecting. The subjects of this research were 15 children aged 5-6 years in one of the schools in the city of Jakarta. Sand media was chosen because it has a texture and properties that can stimulate children's motor sensors and is expected to help children develop pre-writing skills. The results of the research show that children's writing skills in the initial conditions and cycle I have not reached the performance indicators. The results of research in the second cycle show that the use of sand media can significantly improve children's pre-writing abilities, as seen from the increase in accuracy and neatness and the shape of the letters they make. Thus, sand media can be used as an effective alternative in learning pre-writing in early childhood education.

The improved cyclic resistance of bio-treated sands with various gradations for liquefaction mitigation: Density increase and/or cementation?

MICP (microbial induced calcium carbonate precipitation) method shows a huge potential in solving geological and geo-environmental engineering problems, such as liquefaction mitigation, soil remediation, erosion control, slope stabilization and dust control., due to its low-carbon, sustainable and undisturbing character. For the liquefaction mitigation, previous studies showed the remarkable enhancement in cyclic behavior of bio-cemented soils. Little attention has been paid to how soil gradation affects the effectiveness of MICP method in enhancing soil properties, which is one of the key factors of soil mechanical behavior. MICP method has been mainly used in fine sands (mostly <1 mm) with narrow gradation and a certain number of particles smaller than 75 μm. As a result, few papers discussed the application of bio-cementation to soils with larger grains. In addition, the respective contributions of density increase and cementation on cyclic resistance enhancement is still not clear. In this study, a fine sand (0.1–1 mm), a coarser sand (1–5 mm), and a mixture of both, were used, featuring a larger mean size (d50 mm) and uniformity coefficient (Cu) than in most previous studies. In this study, cyclic undrained triaxial tests were performed to analyze the liquefaction potential of loose and dense untreated specimens, and initially loose treated specimens. Results show that sand gradation has a great influence on the cyclic behavior and MICP effectiveness. For all the sands, the MICP treatment gives rise to a significant increase in cyclic resistance and mitigates liquefaction. This enhancement is due to the formation of cementitious precipitates in the pores or on the surface of particles, which creates (1) bridges between particles and/or change in grain characteristics (i.e., size, roughness, angularity), and (2) an increase in density. For sands with various gradations, these two effects differ in magnitude: in the coarsest sand, the effect of density increase appears to be predominant whereas, in the finest and medium sands, the formation of bonds seems to play the major part. These results are important to evaluate the possibility of using this method to improve cyclic resistance in various sands, and to compare the treatment effect with other techniques.

CONSTRUCTED WETLANDS FOR NITROGEN REMOVAL AND SIMULTANEOUS REUSE OF DOMESTIC SEWAGE

This study evaluated the behavior of vertical flow constructed wetland (VFCW), planted with irrigated rice (Oryza sativa L.), specie BRS-GO Guará, and a vertical flow soil filter without plant (VFSF-CTR), as control, both on a reduced experimental scale. The objective was the removal and recovery of N from domestic sewage, using soil latossoil red-yellow (LRY) mixed with medium sand (modified LRY) as support medium. The operation of VFCW and VFSF-CTR for ten months and two rice crop cycles, used three different hydraulic loading rates - HLR (4.0, 8.0 and 15.0 cm/d); with three repetitions, totalizing eighteen experimental units. For the VFCW, the total Kjeldahl nitrogen (KTN) and N-NH4+ removal efficiencies, ranged from 86% to 95%; and, for VFSF-CTR, from 79 to 94%; with the rice crop favoring higher efficiencies in KTN removal, independent of HLR. Both systems showed tertiary treatment removal efficiency in a single stage; in addition, the variations in the removal efficiencies were minimal when operated with HLR of 15 cm/d. There was great accumulation of KTN and mineral N (N-NH4+ and N-NO3-) in soil, mainly in the 0-5 cm soil layer, which can be used for fertilization of other crops. There was also N immobilised in microbial biomass (MBN). This rapid fertilisation improved the soil quality in a short term (ten months of sewage application) and provided the production of grains and vegetable biomass for human and animal food. The VFCW presented good results, either operated with low or high hydraulic loads, showing larger operational flexibility.

Compósito à base de polipropileno reciclado para utilização em instalações agrícolas

ABSTRACT This study aims to develop an eco-friendly, recyclable, and cost-effective composite material for use in storage sheds and machine workshops. The new composite consists of stone dust and gravel bricks bonded by recycled polypropylene through heat treatment. The main focus of this study is to determine the effects of varying polymer proportions on the resistance and permeability properties of the studied composite, intending to achieve optimal properties, i.e., high resistance and low permeability. To do this, the 2² factorial arrangement was employed, comprising four treatments along with three central points, each replicated three times. The data was statistically analyzed at a 95% confidence level from an adapted methodology. This involved tests of compression strength, 3-point bending strength, Los Angeles abrasion, and water absorption by immersion, in which three percentages of polymer content (PC) - 15, 25, and 35% - and aggregates (fine sand, medium sand, and coarse sand - FS, MS, and CS) were used to prepare the composite. The developed composite was deemed suitable for use in storage warehouses and machine workshops, as it presented physical and mechanical appropriate characteristics, i.e., a low water absorption rate and high resistance to compression and abrasion, in addition to being an environmentally friendly composite.

Collapse Pattern in Gypseous Soil using Particle Image Velocimetry

Abstract Gypseous soil is prevalent in arid and semi-arid areas, is from collapsible soil, which contains the mineral gypsum, and has variable properties, including moisture-induced volume changes and solubility. Construction on these soils necessitates meticulous assessment and unique designs due to the possibility of foundation damage from soil collapse. The stability and durability of structures situated on gypseous soils necessitate close collaboration with specialists and careful, methodical preparation. It had not been done to find the pattern of failure in the micromechanical behavior of gypseous sandy soil through particle image velocity (PIV) analysis. This adopted recently in geotechnical engineering to track the motion of soil grains and using tracer particles by applying digital particle image analysis. It has also been used to study the displacement distribution in some cases of granular materials. Therefore, the goal of this study is to find out how gypseous sand medium moves when in contact with a rigid strip foundation that is under static stress and plane strain conditions. The experimental model would focus on two common types of wetting, namely water table rise and dry conditions. The PIV showed that the collapse pattern under the footing is of the type of punching shear failure. The predominant mechanism of soil deformation was the vertical compression of the gypseous granular soil. The results showed that understanding gypseous sandy grain displacement and failure patterns at the local scale is crucial for enhancing the design of foundations under static stress conditions.

Cotransport of Thallium(I) and kaolinite colloids in quartz sand media containing sodium humate: Ionic strength, pH and kaolinite colloid concentration

In real soil environments, humus, colloids and other components significantly affect pollutant migration behavior. Investigating Tl(I) and kaolinite colloids’ cotransport in quartz sand media containing sodium humate (HA-Na) is vital for comprehending Tl(I) migration underground. This study examined the migration of Tl(I) and kaolinite colloids across varying pH levels (5, 7), ionic strengths (ISs) (1, 5, 50 mmol/L), and kaolinite colloid concentrations. Results indicate that lower IS and pH promote Tl(I) migration when transported alone. In cotransport system, kaolinite promotes Tl(I) migration under acidic conditions but inhibits it under neutral conditions, except at high kaolinite concentrations, where the effect shifts from inhibition to promotion. This is primarily due to changes in the zeta potential of quartz sand, HA-Na, and kaolinite, as well as Tl(I) adsorption after HA-Na and kaolinite occupy binding sites. Competitive adsorption between cations and Tl(I) also plays a significant role. Conversely, in individual system, higher IS and pH inhibit kaolinite migration, while increased kaolinite concentration promotes it. In cotransport system, Tl(I) promotes kaolinite migration under acidic conditions but inhibits it under neutral conditions, except at low kaolinite concentrations. This relates to changes in the zeta potential between kaolinite and the medium, as well as the retention of HA-Na in the column and its adsorption onto kaolinite. Competitive adsorption and binding site saturation also have an impact. This study enhances understanding of Tl(I) migration by revealing the dual effect of kaolinite colloids under different environmental conditions, contributing to better knowledge of Tl(I) fate and transport in natural environments.

Stability of Saltwater‐Freshwater Mixing Zones in Beach Aquifers With Geologic Heterogeneity

AbstractSaltwater‐freshwater mixing zones in beach aquifers support biogeochemical reactions that moderate chemical loads in fresh groundwater discharging to marine ecosystems. Existing laboratory and numerical modeling studies have demonstrated that fluid density gradients in the mixing zone can lead to free convection and the formation of density instabilities, or salt fingers, under a range of hydrologic, morphologic, and hydrogeologic conditions. However, salt fingers have rarely been observed in real‐world beach aquifers despite a growing body of field studies investigating intertidal mixing zones. In this study, we used geostatistical methods to generate randomly distributed assemblages of fine and medium sand and incorporated those geologic realizations into variable‐density variably‐saturated flow and salt transport simulations to explore the influence of geologic structure on mixing zone stability in tidally‐influenced beaches. Ensemble‐averaged model results show that geologic heterogeneity inhibits salt finger formation and promotes a stable intertidal mixing zone due to enhanced dispersion. This effect is highest for high degrees of heterogeneity and for more laterally connected geologic architecture. Compared to hydraulically equivalent homogeneous models, sediments with moderate to high heterogeneity produce mixing zones that are on average 19%–29% smaller and 3–10 times more stable due to the absence of the downward convection and seaward movement of salt fingers. The models indicate that geologic heterogeneity may explain the lack of field observations of salt fingers in real‐world intertidal mixing zones. The findings have implications for predicting the onset of free convection in beaches and for understanding intertidal pore water biogeochemistry and chemical fluxes to the ocean.

Analysis of the Effects of Partially Hydrolyzed Polyamide on Oil Reservoir Rocks

The exploitation of heavy oil fields has recently gained momentum due to increased investment in new oil and gas fields and especially due to environmental legislative constraints. That is why in this article I have described the possibility of using partially hydrolyzed polyacrylamide in the exploitation of heavy crude oil deposits, by injecting it into reservoir rocks followed by injection of reservoir water. The role of this polymer is to provide lubrication of the crude oil and water flow channels and especially to block (by reverse osmosis) the large pore communication channels in order to limit pressure leaks in uncontrollable areas. In the study we created two polymers that were used in order to increase the flow rate and decrease the viscosity and the freezing point (additives that are easy to procure and especially with spectacular results in the treatment of stills and without affecting the stability and quality of the final products refinery). We also studied the flow of the polymer through carbonate reservoir rocks, managing to obtain a numerical model that provides data on the rock resistance factor to the flow of partially fluidized polyacrylamide. The adsorption on the surface of the rocks determined the reduction of the mobility of the polymer but also the modification of the gel structure by the modification (crossing) of the polymer (of the polymer chains) which led to clogging (blocking of the pores) and increasing the possibility of fluid flow. In the laboratory we determined the adsorption of silicon for a solution of polyacrylamide of 0.05% partially hydrolyzed concentration in water, it increases from the value of 0.01 mg/m2 to 0.05 mg/m2 when the concentration in NaCl increases from 0 .5% to 10% in are we showed that adsorption increases for pH values ​​lower than 7, and it is stated that for a porous sand medium with a permeability of 140 mD, replacing saline water with 20 g/l NaCl, a presence of the polymer with a concentration of 400 ppm was observed in the effluent, and this value being approximately stabilized after 5 injected pore volumes.

Sediment distribution and transport pattern in the nearshore region, southeast coast of India

The present paper aimed to assess the sediment distribution pattern, mode of transport, and its interaction with hydrodynamic and topographic conditions at different depths and regions along the east coast of India. About 900 surficial sediment samples were collected and analysed on a monthly basis for the Chennai coastal region at 32 stations from 2013 to 2015. The study region is classified into four types, such as beach, inlet, 5 m, and 10 m depth. Sediment textural and grain size trend analyses were conducted to achieve the objectives. Sediment characteristics for the region were recorded as sandy, equally dominated by unimodal and bimodal at the beach, while unimodal at shallow depths (5 and 15 m). The sediments were medium sand to coarse sand at the beach, mostly fine followed by medium at 5 and 15 m depths. The sediment sorting is dominated by moderately well-sorted sediments; the skewness of beach sediments was negative, while nearshore sediments were found positive; average kurtosis values of sediments were noticed to be mesokurtic. The CM plot depicts that the sediments were mostly derived by tractive current, and the modes of transport are “bottom suspension and rolling” and “graded suspension no rolling” at beach locations and shallow water depths, respectively. The GSTA analysis reveals the annual average sediment transport pattern is northerly. The numerical hydrodynamic study confirms the GSTA and CM plot analysis. The study reveals a stable sedimentary environment south of the Chennai port and instability in the northern part. The study includes large spatiotemporal nearshore sediment data with hydrodynamic conditions, immensely helpful to coastal stakeholders and researchers.