Particle Size Distribution Characteristics Research Articles

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.

Extended Monte Carlo modeling for submicron particle size measurement under high light extinction conditions

The light extinction method (LEM) based on Lambert Beer's law (LB) is widely used to characterize particle size distribution (PSD) in multiphase flow. However, as the optical thickness increases with concentration, the phenomenon of multiple scattering is enhanced, potentially leading to reduced accuracy and a limited application range. In this study, an extended Monte Carlo-based light extinction model (EMC) was developed, which was initially employed to calculate and evaluate the impact of multiple scattering. Subsequently, it was used to predict the extinction spectrum that incorporates multiple scattering effects under varying concentrations. To validate the modeling, a compact setup was constructed to perform a series of experiments on polystyrene and silica dioxide (SiO2) suspensions. A differential evolution algorithm was also implemented for the inversion of PSD based on spectral content, with the incorporation of an improved coefficient matrix that considers multiple scattering effects. In comparison to the linear LB model, the EMC exhibits a markedly enhanced capacity in handling higher particle concentrations and improving measurement accuracy. For a 700 nm PS suspension, the particle size inversion error of the EMC can be kept within 4% (93.86% for the LB model) compared with the nominal value, even with an optical thickness of 5.

Preparation and in vitro/in vivo evaluation of uniform-sized Goserelin-loaded sustained release microspheres

Sustained release microspheres loaded with goserelin are regarded as a promising candidate for treating prostate cancer and other sex hormone diseases. However, their widespread adoption has been hindered by issues such as wide particle size distribution and unstable release characteristics. To address these challenges, we employed a combination of the solid-in-oil-in-water microspheres preparation approach (S/O/W) and innovative premix membrane emulsification technology and deeply investigated the effects of four key parameters on the loaded performance of microspheres and the microscopic mechanisms behind them. With this approach, we successfully produced goserelin-loaded sustained release microspheres of narrow particle size distribution (Span 0.642), remarkable encapsulation efficiency (DL = 4.23 %, EE = 93.98 %), low initial burst release (about 0.50 % within 2 h), and compatibility with small injection needles (23-G, inner diameter 0.33 mm, outer diameter 0.64 mm, maximal force 59 N). In the animal model(administered dose, 2.4 mg·Kg−1), goserelin long-acting sustained release microspheres sustained release for over 32 days, maintaining effective concentrations above 2 ng·mL−1, and effectively reduced serum testosterone concentrations to castration levels (<1.0 ng·mL−1) by day 4, maintaining this inhibition for up to 21 days, exhibiting comparable efficacy to the positive control group. In vivo release kinetics analysis revealed that goserelin-loaded sustained release microspheres exhibited a release pattern dominated by diffusion with corrosion assistance in vivo. In summary, the systematic and comprehensive evaluation of uniform-sized goserelin-loaded sustained release microspheres has highlighted their excellent translational potential, and the study herein may provide new strategies and ideas for the development of microsphere dosage forms.

Enhancing soil nitrogen measurement via visible-near infrared spectroscopy: Integrating soil particle size distribution with long short-term memory models

Good quality of soil nitrogen data, which is essential for the advancement of both enhanced agricultural management and ecological environment, traditionally depends on labor intensive chemical procedures. Visible near-infrared (Vis-NIR) spectroscopy, acknowledged for its efficiency, environmental compatibility and rapidity, merges as a promising alternative. However, the effectiveness of Vis-NIR measurement models are significantly compromised by soil particle size distribution (PSD), presenting a substantial challenge in improving the measurement accuracy and reliability. Here an innovative deep learning methodology that integrates PSD with Vis-NIR spectroscopy was proposed for the measurement of nitrogen content in soil samples. By leveraging the LUCAS dataset, different strategies for integrating PSD with Vis-NIR spectral data in deep learning models were explored, revealing that our proposed InSGraL framework, which incorporated mixed features of PSD and spectra as LSTM inputs achieves superior performance. Compared to models utilizing solely Vis-NIR data, InSGraL exhibits a 39.47 % reduction in RMSE and a 42.55 % decrease in MAE, and demonstrates robust performance across various land cover types, achieving an R2 of 0.94 on grassland samples. Moreover, Shapley Additive exPlanations (SHAP) analysis revealed that incorporating PSD modifies the spectral input importance distribution, effectively mitigating spectral interference from particle size while highlighting critical wavelengths previously obscured. This study provides an innovative modeling strategy to mitigate the influence of PSD by integrating it within deep learning framework using Vis-NIR, contributing a deeper understanding of the relationship between PSD and Vis-NIR spectra for the measurement of nitrogen content and offering an effective means to attain soil nitrogen data.

Innovative assessment of reactivity in fly ash: The role of particle size distribution characteristics

The relationship between the intrinsic properties of seven different types of fly ash and the compressive strength of the resulting geopolymers was investigated. A comprehensive examination of the effect of chemical and mineralogical compositions, particle size distribution, on the compressive strength of the fly ash-based geopolymers were performed. Results revealed that particle size distribution had a more significant impact on reaction activity than amorphous phase content or average particle size alone. Therefore, a novel concept of 'reaction volume' based on the geopolymerization reaction mechanism was proposed, which reveals a high correlation between the reactivity of fly ash and the compressive strength of geopolymers, thereby enhancing the predictability of the process. The degree of reactivity, formulated through the integration of reaction volume and amorphous silica-aluminum content, was identified as a robust predictor of compressive strength, which can serve as a crucial tool for evaluating fly ash for the production of alkali-activated materials.

Distribution Characteristics of Soil Aggregate Stability and Organic Carbon of Different Grassland Types in the Temperate Desert of Longzhong Loess Plateau

Soil aggregate stability and organic carbon （SOC） are important indicators of soil structure and quality and play a key role in the improvement of soil quality in temperate deserts. This study aimed to investigate the distribution patterns, stability of soil aggregates, and variation characteristics of the content of aggregate organic carbon in different grassland types in temperate deserts and their interrelationships. Four grassland types in a temperate desert （Kalidium foliatum type, Reaumuria songarica type, Salsola passerina type, and Sympegma regelii type） in the Longzhong Loess Plateau as research objects, and the soil aggregate particle size distribution characteristics were determined using the wet sieving method. The stability of soil aggregates was analyzed by calculating aggregate stability indicators and the contribution of aggregate particle size SOC to bulk soil SOC content. Correlation analysis, principal component analysis, and linear fitting equations were used to reveal the relationship between the soil aggregate content and aggregate particle size SOC and aggregate stability. The results showed that the content of &gt;0.25 mm aggregates （R0.25）, mean weight diameter （MWD）, geometric mean diameter （GMD）, and bulk soil SOC content in each soil layer （0-10, 10-20, and 20-30 cm） of the K. foliatum type grassland were significantly higher than that of the R. songarica type and S. regelii type （P&lt;0.05）. The SOC content of 0.053-0.25 mm and &lt;0.053 mm particle size in each soil layer of the K. foliatum type grassland were significantly higher than that of the S. regelii type （P&lt;0.05）. Surface and subsurface soils （0-10 cm and 10-20 cm） had the significantly highest contribution of 0.25-2 mm particle size SOC to the bulk soil SOC content （P&lt;0.05）. Additionally, as the soil layer deepened, the R0.25, MWD, GMD, bulk soil, and aggregate SOC contents of the K. foliatum type grassland showed a tendency to increase first and then decrease, with the highest contents from 10-20 cm. Kalidium foliatum type grassland aggregate content was dominated by 0.25-2 mm aggregates, whereas the other three grassland types were dominated by 0.053-0.25 mm aggregates. In addition, bulk soil SOC content was significantly correlated with R0.25, MWD, GMD, and ELT （P&lt;0.01）, and the 0.25 mm aggregate was the critical size of positive and negative correlation. R0.25, MWD, GMD, and ELT values were the key factors influencing bulk soil SOC in grassland. The equation fitted to bulk soil SOC content, and GMD was the most suitable to describe the relationship between SOC content and the stability of soil aggregates. Therefore, compared with other grassland types, K. foliatum type grassland had a promoting effect on the soil aggregate stability and the improvement of soil quality.

Finer Particle Size Distribution and Potential Higher Toxicity of Elemental Carbon and Polycyclic Aromatic Hydrocarbons Emitted by Ships after Fuel Oil Quality Improvement.

Ship emissions are a significant source of air pollution, and the primary policy to control is fuel oil quality improvement. However, the impact of this policy on particle size distribution and composition characteristics remains unclear. Measurements were conducted on nine different vessels (ocean-going vessels, coastal cargo ships, and inland cargo ships) to determine the impact of fuel upgrading (S < 0.1% m/m marine gas oil (MGO) vs S < 0.5% m/m heavy fuel oil (HFO)) on elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) emitted by ships. (1) Fuel improvement significantly reduced EC and PAH emission, by 31 ± 25 and 45 ± 38%, respectively. However, particle size distributions showed a trend toward finer particles, with the peak size decreasing from DP = 0.38-0.60 μm (HFO) to DP = 0.15-0.25 μm (MGO), and the emission factor of DP < 100 nm increased. (2) Changes in emission characteristics led to an increase in the toxicity of ultrafine particulate matter. (3) Ship types and engine conditions affected the EC and PAH particle size distributions. Inland ships have a more concentrated particle size distribution. Higher loads result in higher emissions. (4) The composition and engine conditions of fuel oils jointly affected pollutant formation mechanisms. MGO and HFO exhibited opposite EC emissions when emitting the same level of PAHs.

Whole Process Analysis and Fate Behavior of Microplastics in Urban Wastewater Treatment Plants, Including their Occurrence Forms, Components, and Removal Efficiency

Microplastics are among the most difficult new pollutants to remove in wastewater treatment plants. In order to explore the occurrence form, size distribution, composition, removal efficiency, migration law, and fate behavior characteristics of microplastic particles in sewage plants, taking a sewage treatment plant in Hohhot as an example, a total of 17 sampling sites were set up. The LAS X software counted the shape, abundance, and size of microplastics and conducted a full-process analysis. The results showed that： fibrous microplastics had the highest abundance and widest distribution and were the main form of existence, accounting for 61.8% of the total abundance； the size of microplastics ranged mainly between 0 and 1.00 mm, and among the four sizes, the abundance of microplastics 0.25 to 0.50 mm in China was the highest, accounting for 32.9%. Among the eight types of plastic components detected, polyester substances （PET, PBT）, cellulose, and polypropylene （PP） were the main components, accounting for 25%, 21%, and 17%, respectively. The influent abundance of the sewage plant was （73 ±5） n·L-1, the effluent abundance was （14 ±2） n·L-1, and the overall removal rate was （80.8 ±12.1）%. Among the three treatment stages of the sewage plant, only the primary treatment played a role in removal, and the abundance of microplastics surged in the secondary treatment. Different structures playing a major role in the removal of microplastics were fine grids （49.2 ±7.4）% and secondary sedimentation tanks （92.4 ±13.9）%. Microplastics mainly existed in the form of fibers, fragments, and films. The proportion of fibers was approximately 70%, and the size of fragments was mainly concentrated between 0.50 and 5.00 mm. Most fragments were in the range of 5.00 mm, accounting for 50%, making them the main form apart from fibrous. The film-like size was mostly concentrated in the range of less than 0.50 mm, accounting for more than 10%. Therefore, improving the removal of small-sized fibrous and film-like microplastics and large-sized fragmented microplastic particles can effectively reduce the pollution risk of microplastics in the environment caused by sewage plant drainage.

Study on the Population Balance Dynamics Simulation of Grinding under Impact Crushing

During the grinding process, the crushing of minerals mainly depends on the impact action of the grinding medium. Based on the JK drop weight test data of quartz and pyrrhotite and the research results of their impact crushing characteristic parameters, this paper calculates the specific crushing energy (Ecs) of mineral samples subjected to impact in a ball mill using the grinding medium motion theory and then calculates the cumulative particle size distribution under screening under any mesh size using the JK drop weight test method. On this basis, the breakage distribution function of mineral samples is calculated, and a selection function is obtained based on grinding experiments. Finally, using Matlab programming and function-fitting mathematical methods, as well as a particle size population balance dynamics simulation of grinding, the particle size distribution characteristics of the grinding products of the two mineral samples in the mill that are only subjected to impact action are calculated. The results show that the selection function of quartz and pyrrhotite decreases overall with the prolongation of the grinding time, and the selection function of the coarse particle size changes more significantly than that of the fine particle size. At the same time, the selection function decreases with the decrease in feed particle size, and the smaller the feed particle size, the lower the probability of impact crushing. The Ecs values of quartz and pyrrhotite at each particle level in the mill are different, and the degree of mineral crushing is closely related to the impact energy, feed particle size, and mineral properties.

Effect of nanosilica on the hydrological properties of loess and the microscopic mechanism

Loess areas, such as the Loess Plateau, are characterized by a fragile ecological environment, high soil erosion, and frequent geological disasters due to the unique hydrological properties of loess (e.g., collapsibility and permeability). Therefore, the loess must be stabilized for use in engineering construction. Traditional stabilizers (lime, cement, and fly ash) cause environmental problems, such as soil salinization and greenhouse gas emissions. Therefore, this study investigated the effect of nanosilica on the hydrological properties of loess and the microscopic mechanism. Different nanosilica contents (0.2%, 0.4%, 0.8%, 1%, and 3%) were added to loess sample, and the particle size distribution, Atterberg limits, collapsibility, and soil water characteristics were analyzed. The results revealed the following. The addition of nanosilica changed the particle size distribution, liquid limit, plastic limit, and plasticity index of loess. After the addition of nanosilica with different contents, the loess collapsibility coefficient curve shifted downward, the soil water retention curve shifted upward, and the unsaturated permeability coefficient curve shifted downward. The pores between particles were filled, and the number of large and medium pores and the pore connectivity were lower after the nanosilica addition. The surface of the coarse particles adsorbed more fine particles, and a large number of micro-aggregates or clay aggregates were present in the pores between particles. In conclusion, the environmentally friendly material nanosilica can be used to improve the hydrological properties of loess, which is applicable to alleviating soil erosion and preventing geological disasters on the Loess Plateau.

Characterizing and Predicting nvPM Size Distributions for Aviation Emission Inventories and Environmental Impact.

Concerns about civil aviation's air quality and environmental impacts have led to recent regulations on nonvolatile particulate matter (nvPM) mass and number emissions. Although these regulations do not mandate measuring particle size distribution (PSD), understanding PSDs is vital for assessing the environmental impacts of aviation nvPM. This study introduces a comprehensive data set detailing PSD characteristics of 42 engines across 19 turbofan types, ranging from unregulated small business jets to regulated large commercial aircraft. Emission tests were independently performed by using the European and Swiss reference nvPM sampling and measurement systems with parallel PSD measurements. The geometric mean diameter (GMD) at the engine exit strongly correlated with the nvPM number-to-mass ratio (N/M) and thrust, varying from 7 to 52 nm. The engine-exit geometric standard deviation ranged from 1.7 to 2.5 (mean of 2.05). The study proposes empirical correlations to predict GMD from N/M data of emissions-certified engines. These predictions are expected to be effective for conventional rich-burn engines and might be extended to novel combustor technologies if additional data become available. The findings support the refinement of emission models and help in assessing the aviation non-CO2 climate and air quality impacts.

Research on dust control technology and numerical simulation of conical guiding air curtain in fully mechanized excavation face

The dust pollution caused by the operation of fully mechanized heading face poses a serious threat to the safety production of operators and working face. To reduce dust concentration at the fully mechanized heading face, this study analyzed dust samples collected from various positions to understand the particle size distribution characteristics. Based on these findings, a conical diversion air conditioning (CDAC) device was designed to create a radial air curtain for dust control in the roadway cross-section. Computational Fluid Dynamics (CFD) was then employed to investigate the airflow and particle dynamics when the cone-shaped deflector was in closed and open states. The results show that in the fully mechanized heading face, the dust distribution in the working area of the roadheader driver is relatively dense, and the dust particles with particle size ≤ 8 μm account for a large proportion. When the CDAC device is deployed, the axial airflow in the roadway is changed into a rotating airflow along the roadway wall, and an air screen is established in the working area of the roadheader driver to block the outward diffusion of dust. When the pressure air outlet is arranged 30 m away from the tunneling head, the pressure air volume is set to 400 m3/min, and the CDAC device can better form the air curtain barrier to block the dust particles. It provides a new method for effectively controlling the dust concentration of the fully mechanized heading face and directly ensuring the health of the roadheader driver.

Size distribution of brake wear particulate matter based on a brake dynamometer investigation

A brake dynamometer has been modified to accurately study the concentration and size distribution of wear particles in different testing conditions. The test equipment was a charged low-pressure impactor ELPI+ from Dekati, Finland. 29 test conditions were defined based on speed, acceleration and initial brake temperature. Additionally, five different types of brake pads were selected for testing to provide a more comprehensive understanding of the particle size distribution characteristics of brake wear particles. The results showed that the mass of BWPs was unimodal in the range of 0.01–8.11 μm, with peak sizes at 2–5 μm or &amp;gt;8.11 μm, and particles of 0.5–3.0 μm accounted for an average of 49.09% of the total particulate mass, while particles with sizes of 3.0–8.11 μm accounted for an average of 49.72% of the total particulate mass. The number of particles emitted by abrasion had a bimodal distribution, with one in the nucleation mode and the other in the accumulation mode, with peak sizes of &amp;lt;10 nm and 1 μm, respectively; the nucleation mode particles accounted for an average of 60.11% of the total PN10, and the ultrafine particles accounted for an average of 82.15%.

Dissecting PM sensor capabilities: A combined experimental and theoretical study on particle sizing and physicochemical properties

Recent advancements in particulate matter (PM) optical measurement technology have enhanced the characterization of particle size distributions (PSDs) across various temporal and spatial scales, offering a more detailed analysis than traditional PM mass concentration monitoring. This study employs field experiments, laboratory tests, and model simulations to evaluate the influence of physicochemical characteristics of particulate matter (PM) on the performance of a compact, multi-channel PM sizing sensor. The sensor is integrated within a mini air station (MAS) designed to detect particles across 52 channels. The field experiments highlighted the sensor's ability to track hygroscopicity parameter κ-values across particle sizes, noting an increasing trend with particle size. The sensor's capability in identifying the size and mass concentration of different PM types, including ammonium nitrate, sodium chloride, smoke, incense, and silica dust particles, was assessed through laboratory tests. Laboratory comparisons with the Aerodynamic Particle Sizer (APS) showed high consistency (R2 > 0.96) for various PM sources, supported by Kolmogorov-Smirnov tests confirming the sensor's capability to match APSsize distributions. Model simulations further elucidated the influence of particle refractive index and size distributions on sensor performance, leading to optimized calibrant selection and application-specific recommendations. These comprehensive evaluations underscore the critical interplay between the chemical composition and physical properties of PM, significantly advancing the application and reliability of optical PM sensors in environmental monitoring.

Reformulation of white chocolate with soy- and coconut-based vegetable ingredients incorporating encapsulated cinnamon extract: investigation of physicochemical, antioxidant, and sensory properties

ABSTRACT White chocolate, which does not contain cocoa mass, is less healthy than dark and milk chocolate. Due to its milk content, white chocolate can also cause issues for those with lactose intolerance or dairy allergies. To overcome these problems, a study was conducted by adding highly antioxidant encapsulated cinnamon extract (ECE) to vegan white chocolate formulated with different levels of soy protein isolate (SPI) and coconut flour (CF). This study aimed to examine the chocolate’s total phenolics, flavonoids, antioxidant activity (IC₅₀), protein and fat content, particle size distribution, texture, color, melting point, and sensory characteristics. The results showed that the addition of SPI and CF had a significant impact on the properties of the white chocolate, except for hardness. Incorporating 2% (w/w), ECE significantly increased the total phenolics, flavonoids, and antioxidant activity. Total phenolics and flavonoids were positively correlated with antioxidant activity. Vegan white chocolate formulated with 27% SPI, 10% CF, and 2% ECE was acceptable to panelists, and thus, this product can be potentially consumed by lactose-intolerant and vegan consumers.

Multifractal characteristics of soil particle size distribution of abandoned homestead reclamation under different forest management modes

In this study, fast-growing poplar reclaimed from abandoned homestead in Xixian New District, Xi’an City, Shaanxi Province, was used as the research object to explore the multi-fractal characteristics of soil particle size distribution under different management modes of abandoned land (control), irrigation, fertilizer irrigation and mixed fertilizer irrigation. The results showed that the mean values of soil clay, silt and sand in abandoned land were 14.58%, 81.21% and 4.22% respectively, 14.08%, 79.92% and 5.99% under irrigation, 15.17%, 81.19% and 3.64% under fertilizer irrigation, and 16.75%, 80.20% and 3.05% in mixed fertilizer treatment. From 40 cm, with increasing soil depth, soil clay particles increase under irrigation, fertilizer irrigation, and mixed fertilizer irrigation modes. The single fractal dimension of soil particle size distribution (D) in each treatment ranges from 2.721 to 2.808. At 60–100 cm, D shows fertilizer irrigation > mixed fertilizer irrigation > irrigation > abandoned land, indicating that fertilization and irrigation can increase the fine-grained matter of deep soil particles and reduce soil roughness. Compared with abandoned land, under irrigation, fertilizer irrigation and mixed fertilizer modes the capacity dimension (D0), entropy dimension (D1), correlation dimension(D2), shape characteristics of the multifractal spectrum (Δf) and overall inhomogeneity of the soil particle size distribution (D0–D10) indicate an uneven distribution of soil particle size; fractal structure characteristics of soil (D−10–D0) indicate a simplified soil structure, and degree of dispersion of soil particle size distribution (D1/D0) indicates that soil particle size is distributed in dense areas. Pearson correlation analysis showed that D was significantly correlated with clay, sand, D0–D10, soil organic matter (SOM) and soil available phosphorus (SAP) (P < 0.05). Stepwise regression analysis showed that clay was the main controlling factor of D and D0–D10 changes. The research results can provide some potential indicators for the quality evaluation of abandoned homestead reclamation.

Unlocking the nanoparticle emission potential: a study of varied filaments in 3D printing.

This study investigates nanoparticle emission during 3D printing processes, assessing various filament materials' impact on air quality. Commonly used 3D printers, including both filament and resin-based types, were examined. The study's scope encompasses diverse filament materials like ABS (acrylonitrile butadiene styrene), PLA (polylactic acid), PETG (polyethylene terephthalate glycol), ASA (acrylonitrile styrene acrylate), TPU (thermoplastic polyurethane), PP (polypropylene), nylon, and wood-based variants, alongside three types of resins. The research delves into the relationship between the type of material and nanoparticle emissions, emphasizing temperature's pivotal role. Measurement instruments were employed for nanoparticle quantification, including an engine exhaust particle sizer spectrometer, condensation particle counter, and nanozen dust counters. Notably, results reveal substantial variations in nanoparticle emissions among different filament materials, with ASA, TPU, PP, and ABS showing considerably elevated emission levels and characteristic particle size distribution patterns. The findings prompt practical recommendations for reducing nanoparticle exposure, emphasizing printer confinement, material selection, and adequate ventilation. This study offers insights into potential health risks associated with 3D printing emissions and provides a basis for adopting preventive measures.

Inhibiting effects of humic acid on iron flocculation hindered As removal by electro-flocculation on air cathode iron anode

Activated carbon air cathode combined with iron anode oxidation-flocculation synergistic Arsenic (As) removal was a new groundwater purification technology with low energy consumption and high efficiency for groundwater with high As concentration. The presence of organic matter such as humic acid (HA) had ambiguous effects on formation of organic colloids in the system. The effects of the particle size distribution characteristics of these colloids on the formation characteristics of flocs and the efficiency of As purification was not clear. In this work, we used five different pore size alumina filter membranes to separate mixed phase solutions and studied the corresponding changes in iron and arsenic concentrations in the presence and absence of humic acid conditions. In the presence of HA, the arsenic concentration of < 0.05 µm particle size components was 1.01, 1.28, 3.07, 7.69, 2.85 and 1.24 times of that in the absence of HA. At the same time, the arsenic content in 0.05–0.1 µm and 0.1–0.45 µm particle size components was also higher than that in the system without HA, which revealed that the presence of HA hindered the flocculation behavior of As distribution to higher particle sizes in the early stage of the reaction. The presence of HA affected the flocculation rate of iron flocs from small to large particle size fractions and it had limited effect on the behavior of large-size flocs in adsorption of As. These results provide a theoretical basis for targeted, rapid, and low consumption synergistic removal of arsenic and organic compounds in high arsenic groundwater.

A review and analysis of particle size parameters and their relationships to physical properties of growing media

AbstractAn expanded description of particle morphology and the analysis of its relationships with physical properties may help to optimize the selection of raw materials and particle size fractions used as growing media constituents. Previous works have described the outlines of these relations based mostly on sieving procedures to characterize particle size distribution. They have shown limited and sometimes contradictory results due to the different methods used, size fractions selected, and physical properties measured. Also, sieve analysis, which separates particles based on their width, is less accurate for non‐spherical particles, which is the case for most growing media constituents. Recent works have promoted the use of dynamic image analysis (DIA) to precisely analyze both particle length and width. Five raw materials were chosen (white and black peats, coir, pine bark, and wood fiber) and sieved to obtain various particle size fractions. For each particle size fraction and the raw materials, the mean weight diameter (MWD), derived from sieving, was calculated, whereas mean particle length and width were determined using a DIA tool, the QicPic device. Also, physical properties were assessed from water retention curves established using Hyprop systems. The statement that the larger the particle size, the higher the air‐filled porosity (AFP), the lower the water holding capacity (WHC) was more precisely redefined. Large variations in WHC and AFP mainly occurred for finest particle size fractions, whereas changes were conversely very small or non‐existent for larger particle sizes. From data obtained for each particle size fractions, regression models were established to relate mean particle length and width (both determined using DIA) and MWD (determined from sieving) with WHC and AFP. Mean particle length was identified as the most relevant parameter for predicting WHC and AFP of the raw materials tested.

Effect of inlet velocity on the hydraulic and filtering performance of a Y‐type screen filter

AbstractUneven sediment distribution affected by inlet velocity, particle size distribution and flow field characteristics leads to local clogging in a Y‐type screen filter. This study revealed the detailed flow field characteristics and distribution of sediments on the screen via computational fluid dynamics combined with the discrete element method (CFD–DEM) simulations and experimental tests. The results showed that the distribution of the flow rate on the filter screen was extremely uneven, with the maximum flow rate being 11.72 times greater than the minimum rate. The flow rate was distributed symmetrically on the two sides along the outlet centreline, as shown by the unfolded drawing of the filter core. Numerical simulation and experimental tests using sandy water showed that the number and average particle diameter on the screen decreased, and the number and average particle diameter in the plug increased, with increasing inlet velocity. The sediments on the screen were distributed intensively, and the plugging extent coefficient and the anti‐clogging performance improved. However, this process was more likely to cause local clogging and worsen the filtration performance. Therefore, low‐speed filtering should be applied if the filtering effect is needed, and high‐speed filtering should be applied if the filtering efficiency is favourable but the flushing frequency increases.