Μm Sieve Research Articles

Mitigating Microfiber Pollution in Laundry Wastewater: Insights from a Filtration System Case Study in Galle, Sri Lanka

Synthetic fibers are widely used in daily life due to their durability, elasticity, low cost, and ease of use. The textile industry is the primary source of synthetic microfibers, as these materials are mostly used in production processes. Globally, plastic pollution has been identified as a major environmental threat in this era, since plastics are not degradable but break down into smaller particles such as mesoplastics, microplastics, and microfibers. Synthetic microfiber pollution is a significant issue in aquatic ecosystems, including oceans and rivers, with laundry wastewater being a major source. This problem is particularly pressing in cities like Galle, Sri Lanka, where numerous tourist hotels are located. Despite the urgency, there has been a lack of scientific and systematic analysis to fully understand the extent of the issue. This study addresses this gap by analyzing the generation of microfibers from laundry activities at a selected hotel and evaluating the efficiency of a laundry wastewater filtration system. This study focused on a fully automatic front-loading washing machine (23 kg capacity) with a load of 12 kg of polyester–cotton blend serviettes (black and red). Samples (1 L each) were taken from both treated and untreated wastewater during four wash cycles, with a total of 100 L of water used for the process. The samples were filtered through a 100 μm sieve and catalytic wet oxidation along with density separation were employed to extract the microfibers, which were then collected on a membrane filter paper (0.45 μm). Microfibers were observed and analyzed for shapes, colors and sizes under a stereo microscope. Results revealed that untreated laundry wastewater contained 10,028.7 ± 1420.8 microfibers per liter (n = 4), while treated wastewater samples recorded 191.5 ± 109.4 microfibers per liter (n = 4). Most of the microfibers observed were black and white/transparent colors. Further analysis revealed that 1 kg of polyester–cotton blend fabric can generate 336,833 microfibers per wash, which was reduced to 6367 microfibers after treatment. The filtration unit recorded an impressive efficiency of 98.09%, indicating a remarkably high capacity for removing microfibers from wastewater. These findings highlight the potential of such filtration techniques to significantly reduce microfiber emissions from laundry wastewater, presenting a promising approach to mitigating environmental pollution from microfibers.

Effect of coupling between sphericalization and maximum coarse particle content on the cement properties

In this paper, spherical cement with different fineness (45 μm sieve residue) and particle size distributions were prepared using a new dry energy-saving vertical grinder (NDEVG), and the properties and mechanism of cement, which was compared with cement made by roller press-ball mill, under the coupling effect of sphericalization and maximum coarse particle content were investigated. The results indicated that NDEVG can optimize the particle size distribution and improve the roundness to above 0.731. Which was beneficial for improving the packing density and reducing the water requirement of normal consistency of cement. In addition, the coupling effect of sphericalization and maximum coarse particle content created convenience for the overlap of hydration products, resulting in an increase of 7.22MPa at the 28d strength and an effective reduction in drying shrinkage and hydration heat release rate. This work provides technical guidance for the high-quality processing of cement and other powder materials.

Characterization and acid leaching beneficiation studies of Anka (Zamfara State, Nigeria) copper ore deposit

The chemical and mineralogical characterization of the Anka copper was examined and its susceptibility to H2SO4 acid leaching was assessed. A crude sample of the ore, weighing 5 kg, was sourced from the mines, communiated, homogenized, and characterised the crude sample. A 100 g fraction of the crushed sample was subjected to fractional sieve analysis and each sieve retained was chemically analysed. The leaching process was carried out on 100 g of -125+90 µm sieve size fraction using H2SO4 acid and the resulting product was chemically analyzed. The characterization result reveals 42.271% CuO using the energy dispersive x-ray fluorescence spectrometer and the x-ray diffractometer shows that the ore is mainly composed of Cu-carbonate hydroxide in the form of malachite mineral. The scanning electron microscope micrograph suggests that the ore contains dispersed grains of sodium aluminium silicate and copper carbonate hydroxide in a silica-dominated matrix. The ore's liberation size was determined to be at the sieve size of -125+90 μm. Finally, the ore was discovered to be responsive to the H2SO4 acid leaching operation, leading to an enrichment of the feed from 42.27% Cu to a pregnant solution of 52.51% Cu and the residue from the leaching was analyzed to be 4.69% Cu.

Quality Assessment of Igue Calcite Deposit for Industrial Applications

Calcite is one of the primary components of marble and limestone, they made up a significant amount of the crust of the Earth. The goal of the study is to characterize the Igue calcite deposit. Samples were sourced from five different pits, which were homogenized and eventually weighed five kilograms. Of that amount, one kilogram was set aside for laboratory testing and analysis. The sample was first crushed to a size of 1400 µm and then further reduced to 1100 µm using a ball mill. 100 grams of the sample was riffled out for sieve analysis, the particles were classified into 1000µm, 710µm, 500µm, 355µm, 250µm, 180µm, 125µm, 90µm, 63µm, and -63µm, and 125 µm sieve size was sampled out for chemical analysis using an X-ray fluorescence spectrometer. The particle size distribution methods that were employed were the Gates Gaudin Schumann Method and the Rosin Rammler Method. The economic and actual liberation size is at sieve 180µm and 125µm respectively, according to the sieve analysis result mid points is at 49.26% which is the equilibrium point on the graph. The results of the chemical study indicate that the Igue white calcite deposit contains the following elements: Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Co, Fe, Ni, Cu, Zn, As, Pb, W, Au, Ag, and Rb with the mean concentrations of the following: 0.0000, 0.4257, 0.6757, 0.2845, 0.4199, 0.0000, 67.9587, 0.0000, 0.0009, 0.0000, 0.0000, 0.0000, 0.1958, 0.0061, 0.0090, 0.0175, 0.0000, 0.0000, 0.0000, 0.0000, 0.0005 and 0.0000 respectively and intensities of : 0.0000, 0.0014, 0.0076, 0.006, 0.0059, 0.0000, 0.6923, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0012,0.0002, 0.0005, 0.0006, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, Igue white calcite has a good calcium content and intensity, with calcium being the predominant element in the sample and having the following intensity of 0.6923 and content of 67.9587.

Micro plastics removal by Zai water treatment plant, Amman Jordan

Micro-plastics (MPs) concentration, in Zai Water Treatment Plant (WTP) influent, and their removal by the different treatment units have been investigated. Samples were collected from the influent to Zai WTP, and from the effluent of each treatment unit, in December 2022, January, February, May and June of 2023. The samples were sieved at the site using one100 μm, 300 μm and 500 hundred μm sieves. The sieves were rinsed, the rinsed water was collected in 250 ml bottles and brought to the laboratory. The samples were treated and filtered in the Laboratory; two filter papers were prepared for each sample. Filtered samples were tested by Thermo Scientific micro-FTIR spectroscopy, for Microplastic identification, and by fluorescence microscope for MP quantification and morphology. The most frequently identified MPs in the influent were polyester, polyethylene, polypropylene, polystyrene; other MPs were identified at lower frequencies. The results showed that small MPs < 100 μm, in length, were dominant; larger sizes were detected at lower concentrations. The results showed that MPs were removed by the powdered activated carbon unit, coagulation, flocculation followed by sedimentation units, and by the dual media filter. Removal percentages by the different treatment units varied from month to month, which is attributed to the monthly variation in MPs nature and size distribution; variation of MP concentration in the influent; and variation in the operational conditions. Overall MP removal efficiencies were (48, 29, 53, 91, 84) %, for December, January, February, May, and June samples, respectively.

Kerosene or hydrogen peroxide? Comparison between recovery methods of mineralized microfossils in siliciclastic rocks

One of the most important steps in the recovery of mineralized wall microfossils is chemical preparation. However, this process can often be destructive to microfossils if they are not applied extremely carefully. In this way, this research tested two different methods of micropaleontological preparation to compare the rock disaggregation and the amount of recovered microfossils between the two methods. To achieve the objective, the samples were attacked with 20% hydrogen peroxide concentration and pure kerosene in fractions of 200g of each collected sample. Thirteen samples were collected, with different compositions, such as sandstones, shales, heteroliths and siltstones. After preparation, the samples were washed over sieves with a mesh between 420 and 75 μm. The disaggregation rate was calculated based on the initial mass and the mass retained on the 420 μm sieve. These values were plotted in a scatter diagram and the dispersion coefficient r was calculated, which indicated a strong positive linear correlation between the two methods. The strong linear correlation between the disaggregation rate of the samples indicates that probably the parameters that influence the rock disaggregation are intrinsic to its characteristics. Regarding the recovery of microfossils, in the kerosene method the hyaline foraminifera and phytoclasts presented a better preservation, while in the hydrogen peroxide method the agglutinating foraminifera had a better recovery. As a secondary result this research presents new data about the microfauna of the Rio Bonito Formation. The taxa retrieved were the genus Paralingulina, Thuramminoides?, Saccammina and fusiform morphotypes, three phytoclast, an ostracod and unidentified bioclasts.

Eupatorium Adenophorum Spreng as a green additive in cementitious materials for sustainable infrastructure

The use of natural admixtures as a sustainable alternative to cement and chemical admixtures in concrete has gained significant attention. Eupatorium adenophorum Spreng (EAS), commonly known as the ‘forest killer’ in Nepal, is a perennial and herbaceous invasive plant. This prompted an experimental investigation aimed at assessing the potential utilization of its liquid and burnt ashes as additives in cement mortar. EAS leaves were dried, burnt at wooden coal fire, and sieved through a 90 μm sieve to obtain EAS powder. EAS liquid was produced by hammering the fragmented leaves, followed by squeezing and filtering. The control mortar had a water-cement ratio of 0.35 and a cement-sand ratio of 1.0. EAS powder content ranged from 0 % to 15 % and EAS liquid from 0 % to 0.4 %, by weight of cement. The optimal content (10 %) of EAS powder resulted in decreases in flow table value, density, and elastic modulus of mortar by 2.3 %, 4.2 %, and 10.6 %, respectively, while increasing compressive strength and water absorption by 2.3 % and 14.6 %, respectively. As for EAS liquid, its optimal content (0.3 %) led to increases in flow table value, density, compressive strength, elastic modulus, flexural strength, and splitting tensile strength by 11.0 %, 1.4 %, 13.0 %, 25.4 %, 28.4 %, and 33.0 %, respectively, while decreasing water absorption by 2.7 %. The observed increase in the compressive strength of mortar with the incorporation of EAS powder suggests its potential to substitute mineral admixtures. This can be achieved through improvements in the burning process, grinding to finer particles, and thorough micro-characterization, followed by detailed investigations into mortar properties. Additionally, the effectiveness of EAS liquid in replacing chemical admixtures to enhance various mortar properties has been confirmed. The collaborative use of EAS powder and liquid holds promise for supporting future sustainable infrastructure development, facilitating the production of eco-friendly green concrete.

Lite RGB-based measurement method for ballast fouling index prediction through subsampling

Ballasted track is the major form of freight railroads. Despite various requirements for material selection, ballast will degrade due to wear and the infiltration of fine materials. These fine particles will cause ballast fouling and degraded track performance. The fouling condition is directly related to both ballast performance and track maintenance planning. It can be quantitatively assessed using the Fouling Index (FI), calculated as the sum of the percentages of materials passing through No. 4 (4.75 mm) and No. 200 (75 µm) sieves. Traditional fouling assessment methods rely on labor-intensive sieve analysis. While non-destructive techniques such as Ground Penetration Radar, Impulse Response, Surface Wave, and SmartRock offer alternatives, they require specialized equipment and skilled technicians for accurate interpretation. Deep learning models have also been employed, trying to assess ballast fouling conditions by segmenting particles. However, these models struggle to account for fine materials. Recently, the FI was found to be linearly correlated with the variance of RGB (Red, Green, Blue) intensities in fouled ballast images, and this correlation could be used to assess ballast fouling conditions. Improving upon the previously developed FI prediction model and making it more practical, this study proposes an enhanced and lite RGB-based model that predicts the FI through a simple random subsampling approach. The optimal subsample size is determined both experimentally and analytically. Based on the results obtained from this study, the correlation between FI and the variance of RGB intensities in fouled ballast images is further confirmed. The proposed lite model can achieve the same accuracy in FI prediction but requires fewer than 1 % of the data points needed by previous methods, which demonstrates its promising potential for ballast fouling condition assessment practice.

Variation in seed morpho-physiological traits of Nauclea orientalis L. in a seedling seed orchard and the effect of seed sortation on their physiological parameters

The aim of this study was to identify the morpho-physiological diversity of seeds in several mother trees of N. orientalis at 6-year-old in a seedling seed orchard in Parungpanjang, Bogor and to identify the effectiveness of seed sortation in improving the seed germination. A total of 17 mother trees were collected for their fruit, measured the morphology of the seeds and tested their germination. The results showed that fruit and seed dimensions and weight, germination capacity were strongly influenced by the mother tree. Germination capacity and the highest germination capacity was resulted by family no. 22-BT (90%) and 48-MJ (92%). The highest coefficient of variation was given by seed weight per fruit (83.03), followed by germination capacity (66.66) and fruit weight (65.95). Seed sortation had a significant effect on germination capacity, germination rate, and mean germination time, but had no significant effect on germination value. In general, a sieve size of 300-420 μm gave the best results for increasing germination capacity (59.5%), germination rate (1.67% day-1), and mean germination time (18 days). Other sieve sizes, i.e., 420-600 μm was also able to improve seed germination so that for seed sortation applications 300-600 μm sieve sizes can be used.

Investigating the Gravity Beneficiation Consequence on Farin-Lamba (Plateau State) Cassiterite towards Tin Oxide Production

This research aims to assess the amenability of Farin-Lamba cassiterite to the gravity concentrations techniques towards tin oxide production. The ore was subjected to fractional sieve size analysis, work index, and the concentration test to gravity method using the Wilfley shaking table and Spiral concentrator processing. Fractional sieve analysis of the crude sample was carried out at a sieve range of 500-63 µm towards liberation size determination. Five hundred (500) g each of Farin-Lamba cassiterite and Igbokoda silica sand was prepared by grinding to 100% passing 500 μm sieve towards work index determination and the gravity separation method was determined using the Wilfley shaking table and spiral concentration method. The fractional sieve size analysis carried out revealed that the Tin oxide-bearing mineral can be liberated at the particle size fraction of -180 + 125 μm. The work index alongside the energy expended in grinding the ore was found to be 9.980 Kwh/ton and 2.435 Kwh respectively. The chemical analysis of the ore concentrates revealed that the optimum yield was obtained at +125 µm assaying 62.74% SnO2 for Wilfley shaking table and 60.07% SnO2 for spiral concentration.

Influence of Ultrafine Steel Slag Powder Content Upon Cement Mortar

Steel slag (Electric Arc Furnace Steel Slag) is a by-product left over from the conversion of iron to steel in steel industries. This paper reports the results of an experimental study on partial replacement of ordinary Portland cement (OPC) with steel slags powder produced in Libya (Libyan Iron and Steel Company). The effects of various replacement ratios of ultrafine steel slag powder to Portland cement (i.e., 10%, 20%, 30%, 40%, and 50%) on the workability, mechanical, physical and chemical properties were studied. The fineness of steel slag powder was standardized by using a 63 μm sieve. The properties of cement pastes and mortars with ultrafine steel slag powder were tested including water requirement of normal consistency, setting time, soundness, fluidity, dry bulk density, total porosity, water absorption capacity. compressive and flexural strength. The results showed that for cement pastes with ultrafine steel slag powder, the normal consistency water requirement were increased significantly. Both the initial setting time and final setting time were also accelerated than that of the control sample. The partial replacement of cement by ultrafine steel slag powder decreases the compressive and flexural strength, but increases the fluidity which improves the workability of the mortar. The results showed that the optimum content of ultrafine steel slag powder as a replacement of OPC was 10%.

Isolation and Characterization of Starch from Different Potato Cultivars Grown in Croatia

Starch is a polysaccharide that is widely used in food and other industries; therefore, due to its great potential, it is attempted to be maximally isolated from various foods rich in starch. Commonly, potatoes are used for starch production due to the relatively high starch content in tubers, and the process itself is complex and includes several steps. The aim of this study was to isolate and characterize starch from eight potato varieties. First, the basic chemical composition of the potato samples was determined, and then the isolation was carried out under laboratory conditions. The isolated starch was air dried, then ground and sieved through a 400 µm sieve. The basic chemical composition, amylose content, starch color, swelling capacity and solubility index, clarity of starch pastes, texture of starch gels and thermo-physical properties (gelatinization and retrogradation) were determined in the obtained starch samples. The results showed that the SL 13–25 potato variety had the lowest starch content, while the Stilleto variety had the highest starch content. The content of protein, fat, ash and crude fiber was relatively low in all of the isolated starches, indicating their high purity. Also, the difference in the color of the isolated starches was difficult to see. The highest amylose content had starch from Saprodi, while the lowest was observed in starch from SL 13–25. Starch from the cv. Dartiest had the highest, while starch from the cv. Sereno had the lowest gel strength. The starch of the cv. Dartiest also had the highest clarity value. The retrogradation transition temperatures and enthalpies were lower compared to the gelatinization temperatures and enthalpies. With the increasing temperature, both the swelling capacity and the solubility index of all the samples increased. According to the obtained differences, this study confirmed the significant influence and role of different cultivars on starch characteristics.

Recycling Local Waste Glass Bottles into Cement Paste: Effect on Hydration, Microstructure, and CO2 Emission.

Large amounts of waste glass are generated along with the manufacturing of glass products, causing detrimental effects on the environment. Through crushing and ball-milling, waste glass powder (WGP) can be acquired from glass bottles and has been suggested in cementitious systems due to its potential pozzolanic activity. To better understand the impact of WGP on cementitious composites, experimental tests of rheology, heat of hydration, and strength development were conducted on cement pastes with and without WGP. Results show that the rheological performance of cement paste is improved when WGP with particles passing through 80 μm sieves is incorporated. The retarding effect and pozzolanic reaction were observed through X-ray diffraction patterns and thermo-gravimetric parameter analyses. A calcium hydroxide (CH) content calculation further confirms the secondary reactivity of WGP in cement pastes. Compared with the samples without WGP, the normalized CH content of binder per unit mass containing 35% WGP decreased by 21.01%, 24.94%, and 27.41% at the ages of 1, 28, and 90 days, respectively, which contributes to late-age strength development of pastes. At the same time, the hydration per unit of cement was increased by 21.53%, 15.48%, and 11.68%, which improved the cement efficiency. In addition, WGP particles provide nuclei for hydration products, facilitating the subsequent growth of C-S-H and strength development in late ages. Based on value engineering analysis, WGP was found to reduce the impact of Portland cement on the environment by 34.9% in terms of carbon dioxide emissions, indicating a bright prospect for WGP in the cement industry.

Partial Substitution of Asphalt Concrete Filler with Eco-Friendly Burnt Sawdust

This paper investigates the effects of burnt sawdust as an additive in asphaltic concrete, aiming to enhance the material's properties. The study sourced redwood sawdust from a carpentry workshop in Djelfa state, Algeria, and obtained bitumen, coarse aggregates, fine aggregates, and mineral filler from the Public Works Laboratory for the South in Ghardaïa state, Algeria. The sawdust was burned at 200°C in a furnace, cooled, and sieved through an 80 µm sieve. Standard procedures were employed to determine the material properties. Asphaltic concrete samples were then prepared with burnt sawdust at varying weight percentages of 0, 5, 15, 20, and 25% of the filler. The Marshall Stability test was conducted to assess the mixtures' stability, flow, density, voids filled with bitumen (VFB), air voids (AV), and voids in mineral aggregate (VMA). The results indicated an optimal sawdust content of 15%, showcasing improved properties when burnt sawdust was added to asphaltic concrete. Additionally, this utilization of sawdust contributes to preserving nonrenewable materials and reduces pollution from mineral filler manufacturing. Furthermore, the use of fine sawdust, typically considered waste, proves an environmentally responsible alternative to disposal.

Manufacture and Characterization of Adsorbers Utilizing Pahae Natural Zeolite-Chicken Eggshell for Purifying Used Cooking Oil

This research investigates the synthesis and characterization of Pahae natural zeolite-chicken eggshell adsorber to refine used cooking oil. The primary objective is to develop effective adsorbents for enhancing the quality of used cooking oil through refining. The methodology involves sieving the zeolite through a 74 µm sieve, chemically activating it using a 10% KOH solution for 1 hour and drying it at 100°C. The eggshells are also sieved through a 74 µm sieve, followed by washing and drying at 105°C for 12 hours. Various combinations of natural zeolite and chicken eggshell compositions (100% : 0%, 0%: 100%, 95%: 5%, 90%: 10%, 85%: 15%, 80%: 20%) are then prepared and pressed using a hydraulic press under a load mass of 6 tons for 10 minutes. The resultant samples are further activated by heat treatment at 600°C for 2 hours. The adsorbents undergo a comprehensive characterization process, encompassing physical properties (porosity and water absorption), mechanical properties (hardness), surface morphology (SEM), elemental composition (XRF), X-ray diffraction (XRD) analysis, and practical applications assessment (density, viscosity, moisture content, color, and odor). The optimal adsorbent configuration is identified as 80% natural zeolite and 20% chicken eggshell composition, activated at 600°C, exhibiting a porosity of 81.54% and an oil absorption of 46.86%. The highest hardness value of 119.64 MPa is achieved with 100% natural zeolite composition at 600°C. SEM analysis indicates an average pore diameter of 1.232 µm, while XRF results highlight calcium (Ca) as the predominant element at 49.64%. XRD analysis confirms the formation of a rhombohedral crystal structure.

Waste Glass “An Alternative of Cement and Fine Aggregate in Concreteˮ

The major aim of this study is to use Waste Glass Powder (WGP) which is obtained from grinding glass waste using an abrasion apparatus, as cement and a fine aggregate substitute in concrete. The physical and mechanical characteristics, workability, and compressive strength of concrete were studied by using WGP as cement and fine aggregate replacement simultaneously. In order to perform correctly, the glass has to be sieved to particle sizes of less than 150 µm sieve for cement replacement and 4.75 mm for fine aggregate replacement. WGP was used to replace the cement and fine aggregate in concrete, yielding products with respective cement contents of 10.0% and 15% and fine aggregate contents of 15.0% and 20%, and the properties of this concrete have been compared with reference specimens with zero replacement. Cube specimens were cast, cured, and tested for compressive strength and workability at 7, 14, 28, and 56 days of age, and the results were then compared to those of traditional concrete. The use of WGP as a cement and fine aggregate substitute resulted in a reduction in concrete's compressive strength and workability. However, the findings revealed that WGP could be used as a partial substitute for cement and fine aggregates, with 10 to 15% of cement and fine aggregate substitution by WGP being the optimum in terms of strength and economy. As a result, we can utilize it in structures that are moderately heavy.

Iron removal from kaolin by oxalic acid using a novel pre-agitating and high-pressure washing technique

AbstractThis study reports a leaching process along with a novel physical pretreatment technique to remove iron impurities from kaolin using oxalic acid. A detailed examination of the physical properties of the minerals confirmed that almost none of the leaching-resistant iron oxides, specifically hematite, was completely interlocked with the clay minerals. Accordingly, a pre-agitating technique followed by high-pressure washing of the sample on a 600 μm sieve were applied. In this method, by discarding up to 20% of the raw material, &gt;54% of the total iron content of the raw kaolin was removed, and the iron content was reduced from 9.75% in the initial sample to &lt;6.00% in the passing fraction. Application of this pretreatment method rendered the leaching process successful at 97°C using 0.3 M oxalic acid solutions for 1 h under atmospheric pressure. Compared to the leaching of the raw material without pretreatment, which consumed at least 0.5 M oxalic acid over a minimum period of 2 h, the method used was very cost-effective and favourable, reducing the iron content of the product to &lt;1% and producing high-quality kaolin.

Current condition of shallow-water benthic foraminifera in Manado bay, Indonesia

Coral reef community in Manado Bay is under pressure due to human activities in areas in and around Manado. In order to be able to wisely manage the bay area and the coral reefs in it, information about present conditions is needed. The use of marine organisms as bioindicators is one way to find information about the condition, and organisms such as foraminifera have the potential to be used as some species share the same requirement for water quality as the corals. Sampling for the foraminifera was carried out at 10 locations, and the depth of water ranged from 2.5 m to 7.0 m. The samples obtained were washed through a 63 μm sieve and dried. The separation of foraminifera tests from other sediments was done under a stereomicroscope and they were then identified to genus level. A total of 40 genera was identified among 3194 specimens. To get the FoRAM Index value, the foraminifera was categorized into three functional groups. 8 genera were categorized as symbiont-bearing group, 8 as opportunistic group, and 29 as heterotrophic group. FoRAM Index was found to be varied from 2.06 to 9.19 which indicated that Manado Bay water condition is also varied among the sampling area. In general based on the data obtained, it is assumed that water in Manado Bay is conducive for coral reef growth.

Mechanical, durability and microstructural characteristics of Portland pozzolan cement (PPC) produced with high volume pumice: Green, cleaner and sustainable cement development

Nowadays, it is frequently preferred to use pozzolans instead of clinker to reduce the CO2 emissions that increase with cement production. Because in the future, the release of artificial pozzolans, such as fly ash and blast furnace slag, will decrease. Therefore, the demand for natural pozzolanic cement will increase. This study aimed to produce Portland Pozzolan Cement (PPC) by using pumice instead of clinker up to 40%. The Chemical, physical, mechanical, durability, microstructure, and carbon footprint characteristics of PPCs were investigated experimentally. As the pumice volume in the PPCs increased, the CaO/SiO2 ratio and specific gravity decreased. Due to the hygroscopic moisture of the pumice, its grindability has become difficult. While the 40 µm sieve residue of PPCs ranges from 0.8 to 1.7%, the sieve residue ratio generally increases as the pumice volume increases. The porous structure of pumice led to an increase in Blaine fineness as the replacement ratio increased. The Blaine fineness of PPCs containing 40% pumice rose by about 20% more than the reference cement. The consistency water of PCs varies between 29 and 36%. As the water consistency increased, the setting time of the pastes was prolonged. Initial setting times of PPCs are between 150 and 220 min. If the CaO/SiO2 ratio decreased with the pumice volume, the compression strength of the mortars decreased. While the 28-day compression strength of PPC containing 10% pumice was measured as 36.2 MPa, this value was measured as 21.6 MPa for PPC containing 40% pumice. As the pumice volume increased, the mortars' drying shrinkage and sulfate-induced expansion values decreased significantly. According to the sustainability analysis, the CO2 emissions of cement vary between 518 and 880 kg CO2/t. By using pumice instead of clinker, CO2 emissions of cement can be reduced. In SEM examinations, it was determined that pumice concentrated the microstructure. As a result, it has been determined that eco-friendly cement can be obtained by using 10% and 20% pumice in PPC production.

Microplastic distribution and characteristics across a large river basin: Insights from the Neuse River in North Carolina, USA

While microplastics (MP) have been found in aquatic ecosystems around the world, the understanding of drivers and controls of their occurrence and distribution have yet to be determined. In particular, their fate and transport in river catchments and networks are still poorly understood. We identified MP concentrations in water and streambed sediment at fifteen locations across the Neuse River Basin in North Carolina, USA. Water samples were collected with two different mesh sizes, a trawl net (>335 μm) and a 64 μm sieve used to filter bailing water samples. MPs >335 μm were found in all the water samples with concentrations ranging from 0.02 to 221 particles per m3 (p m−3) with a median of 0.44 p m−3. The highest concentrations were observed in urban streams and there was a significant correlation between streamflow and MP concentration in the most urbanized locations. Fourier Transform Infrared (FTIR) analysis indicated that for MPs >335 μm the three most common polymer types were polyethylene, polypropylene, and polystyrene. There were substantially more MP particles observed when samples were analyzed using a smaller mesh size (>64 μm), with concentrations ranging from 20 to 130 p m−3 and the most common polymer type being polyethylene terephthalate as identified by Raman spectroscopy. The ratio of MP concentrations (64 μm to 335 μm) ranged from 35 to 375, indicating the 335 μm mesh substantially underestimates MPs relative to the 64 μm mesh. MPs were detected in 14/15 sediment samples. Sediment and water column concentrations were not correlated. We estimate MP (>64 μm) loading from the Neuse River watershed to be 230 billion particles per year. The findings of this study help to better understand how MPs are spatially distributed and transported through a river basin and how MP concentrations are impacted by land cover, hydrology, and sampling method.