Drainage Test Research Articles

Estimation of the Hydraulic Parameters of a Stratified Alluvial Soil in the Region of El Haouareb—Central Tunisia. Experiments, Empirical, Analytical and Inverse Models

Modeling water flow and contaminant transport in the unsaturated zone is a difficult task that relies heavily on good hydrodynamic soil characterization. This article presents a complementarity between experimentation, direct modeling and inverse modeling in order to provide a better estimate of the hydrodynamic parameters of stratified alluvial soil in the El Haouareb region of the Kairouane plain in Tunisia. A field sampling campaign was carried out. The samples collected underwent particle size analysis, bulk density measurements and infiltration tests using a mini-Muntz. In parallel, simple evaporation tests were applied to separate strata. In addition, a 2 m soil column was reconstituted and fitted with sensors to monitor water content, tension, temperature and electrical conductivity. An internal drainage test was performed on this monolith. Three methods were applied using experimental data to estimate soil hydrodynamic parameters. In the first method, pedotransfer functions were used (Rosetta platform) based on granulometric results and bulk density. In the second, water tension and water content monitored during the simple evaporation test were used to plot the soil–water retention curve (SWRC) using SWRC-Fit. In the third method, inverse modeling was applied to the internal drainage test. A comparison of the results showed that the inverse method had the lowest RMSE. Uncertainty analysis has been implemented for both the experimental and numerical set up.

Development patterns of the dynamic elastic modulus of saturated coral sand under different drainage conditions

Long-term cyclic loading can have a significant effect on the modulus of sand, and the influence on saturated coral sand has yet to be established. In this paper, the significant influence of non-plastic fines content (FC) and relative density (Dr) on dynamic elastic modulus (E) of saturated coral sand has been evaluated by a series of cyclic triaxial drainage tests. The results show that the dynamic elastic modulus increases rapidly at the beginning of loading; then the growth slows down and finally stabilizes. In general, the development of E is influenced collectively by FC, Dr and cyclic stress ratio (CSR). The initial dynamic elastic modulus Ed-1 and steady-state dynamic elastic modulus Ed-s increase with the increase of Dr, and decrease as FC increases. The linear fitting equations are given by introducing the equivalent skeleton void ratio esk*. Furthermore, the relative dynamic elastic modulus Er is defined as the ratio of Ed-N to Ed-s, and the prediction equation for Er was developed to provide a basis for the engineering mechanical parameters of coral sands under long-term loads.

Effects of clay grains on the shear properties of unsaturated loess and microscopic mechanism

Different clay grains affect the structural strength of loess through the cementation of skeletal particles. This study investigates both clay-clay grains and quartz-clay grains. Clay-clay grains mixed loess (CM-L) and quartz-clay grains loess (Q-L) samples were prepared, and their unsaturated shear properties analyzed. X-ray diffractometry (XRD) analysis was conducted to determine the types and proportions of clay grains. Ball mill grinding and laser particle size analysis were employed to ensure comparable sizes of clay grains, while mercury intrusion porosimetry (MIP) tests confirmed similar pore characteristics. Scanning electron microscope (SEM) and unsaturated triaxial consolidation and drainage tests explored the impact of different clay grains on loess shear characteristics, assessing both microscopic and macroscopic performance. The results indicate that CM-L loess exhibits higher cohesion and a lower internal friction angle at the same matric suction level. The cohesion and internal friction angle of both CM-L and Q-L loess exhibit a linear relationship within the range of 50–200 kPa matrix suction. The cohesive force ranges for CM-L and Q-L loess are 60.31–80.07 kPa and 43.01–69.60 kPa, respectively, while the ranges for internal friction angles are 19.95°-19.59° and 25.91°-25.06°, respectively. Compared to Q-L loess, CM-L loess exhibits an average difference in cohesion of 23.18 kPa and in internal friction angle of -5.72°. The microscopic variation in shear strength can be attributed to the “fish scale-like” interlocking state between clay-clay grains and the “tower-like” scattering arrangement of quartz-clay grains. In conclusion, the effect of different clay-grain types on the shear strength of loess varies significantly. The present study elucidates the relationship between the influence of different clay grains on the mechanical properties of loess and their microscopic structural characteristics, thereby providing crucial data for investigating the microscopic effects on the structural strength of loess.

Characterization, potential valuable metals recovery and remediation of historic wolframite mining waste

The understanding of tungsten (W) mineral weathering and mobilization in nature remains limited due to W being a transition element with a wide range of oxidation states, which enables it to form a variety of complex chemical compounds. This study examined W mining waste at the abandoned Wolfram Camp mine in North Queensland, Australia, to address this gap. The mineralogical analysis showed the W tailings primarily consisted of silicates, including quartz, illite/mica, plagioclase, and K-Feldspar, with low WO3 content. Static acid mine drainage (AMD) tests indicated most tailings were non-acid forming, while groundwater samples exhibited acidification, with pH ranging from 3.8 to 5.2. The reprocessing trials using gravity separation and bioleaching demonstrated promising results, suggesting both techniques could effectively recover resource and decontaminate the mining waste. The gravity separation reprocessing test has successfully recovered 48.4% W from the tailings, with the resulting W concentrate achieving a 21.6% WO3 grade. On the other hand, the bioleaching reprocessing exhibited a remarkable 44-fold enrichment of W from the tailings, with 2.2% W in the AMD sediment. Synchrotron-based XFM/μ-XANES imaging analysis revealed significant wolframite weathering in reprocessed W concentrates. This study proposed a comprehensive approach, integrating environmental remediation and resource recovery technologies, to repurpose abandoned W mining waste. Passive treatment appears to be an economical option for remediating abandoned W mine sites. The findings provide valuable insights for sustainable W mining waste management and the rehabilitation of the abandoned Wolfram Camp W mine site.

Steady-state two-phase relative permeability measurements in proppant-packed rough-walled fractures

Understanding multiphase flow in fractures filled with minerals and proppants is vital in various subsurface applications. Limited experimental data have led to reliance on correlations lacking physical basis. We conducted experiments to characterize relative permeability in rough-walled fractures packed with unconsolidated porous media. We tested fractures packed with water-wet 40/70 sand (silica) and surface-coated ceramic proppants. Brine and mineral oil were used as the wetting and non-wetting fluid phases, respectively. Steady-state (SS) drainage (non-wetting-phase displacing wetting-phase) and imbibition (wetting-phase displacing non-wetting-phase) tests were performed under a wide range of saturation histories (full-cycle and scanning-curves) to study relative permeability hysteresis of the propped fractures. Every SS drainage or imbibition test consisted of several discrete points at which fluid saturations and the corresponding relative permeability were measured by varying the fractional flow rates of fluids whilst maintaining a constant total flow rate. We analyzed residual non-wetting phase saturations and relative permeability trends to understand two-phase flow behavior in each proppant pack. High-resolution x-ray microtomography was used to understand the pore-scale topology, wettability, and to provide insights about the pore-scale displacement mechanisms involved in this study. The results showed that commonly used models to estimate relative permeabilities of fractures significantly overestimated the SS brine and oil relative permeabilities (denoted as krw and kro) measured in this study. Further analysis unveiled that the kro values during imbibition exceeded their drainage counterparts in both proppants, the ceramic proppant exhibited a lower initial water saturation and a higher end-point kro permeability at the end of the drainage displacement, as well as higher krw across all flooding processes. Updated fitting parameters for a Brooks-Corey-type relative permeability correlation are introduced. This study presents improved insights, extensive experimentally generated relative permeability data, and an updated relative permeability correlation, which can be collectively utilized to reduce uncertainties associated with continuum-scale forecasts of multiphase flow behavior in fractured subsurface formations.

Meso-structural evolution characteristics of porous asphalt mixtures with stress-induced and their effects on environmental functions

This study aims to investigate the meso-structural evolution characteristics of porous asphalt mixtures (PAM) under stress and their effects on drainage and noise reduction environmental functions. Digital image processing technique was used to accurately identify the internal voids during uniaxial compression testing. The focus was on analyzing and simulating meso-scale differences in internal void structures before and after deformation and quantifying the evolution of these voids during the strain process. Drainage and noise reduction tests were conducted, and correlation analysis and factor screening were performed. The results indicate that in stress-induced meso-structural evolution, contact between aggregates generates force chains, and with increasing strain, the length of these chains and the number of aggregate contacts increase. Significant forces occur at the interface between aggregates and asphalt mortar. Aggregates undergo relative translational motion due to resistance to loads, resulting in compressed voids, cracks between asphalt mortar and aggregates, and gradual deterioration of the mixture structure. Additionally, the increase of strain significantly reduces the drainage and noise reduction performance of porous asphalt mixtures. The scale relationship diagram between macro- and meso-scale indicators identifies strain, void area and void sphericity as the primary influencing factors. The research findings contribute to understanding the stress transfer characteristics of PAM at the meso-structural scale, thereby enabling adjustments to grading, optimization of void structures, and enhancement of their long-term environmental functions.

Development of a modified hypoplastic model for calcareous sand considering particle crushing

In the field of ocean engineering, calcareous sand is frequently employed. However, particle breakage can significantly reduce its strength and dilatancy while increasing its compressibility, leading to potential safety and stability issues for foundations. Traditional constitutive models have limitations in accurately describing the mechanical behavior of calcareous sand. To address this issue, a modified hypoplastic model is proposed in this study, incorporating the quantified indicator of relative particle breakage rate, Br. The established stress-strain relationship is intricately linked to the Br index, effectively connecting it with the effective stress and deviatoric stress. The effect of particle crushing on the critical friction angle, CSL parameters and α parameter of the hypoplastic model were systematically analyzed. A VUMAT subroutine is developed to assess the precision and applicability of the proposed model by simulating triaxial drainage tests under three different densities. The simulation results exhibit good agreement with experimental data, demonstrating the superiority of the modified model over the conventional hypoplastic model. This modified model proves suitable for calcareous sands with varying densities, making it a valuable tool for enhancing stability and safety in ocean Engineering Geology.

Pore parameter selection for fused deposition modeling of gas diffusion layers in proton exchange membrane fuel cells

AbstractBecause of the global energy crisis, many researchers have focused their efforts on fuel cells. The gas diffusion layer (GDL) is a fundamental component of proton exchange membrane (PEM) fuel cells. The manufacturing procedures for traditional carbon‐based GDLs are sophisticated and energy‐intensive, and have design flexibility constraints, making it difficult to build complicated forms and structures. Additive manufacturing is widely used in a variety of fields, with the fused deposition modeling (FDM) technique being the most popular method. Prior to conducting systematic research on the printed GDLs, it is necessary to investigate the pore parameters with the support of FDM technique. In this research, the initial step involves material selection, FDM printer selection, and modeling. Subsequently, printing analysis and sample characterization are conducted to select an acceptable pore shape. A water drainage test determines the appropriate pore size, followed by additional tests for acceptable porosity range. The square pore shape is determined to be more suitable. A pore side length of 1.0 mm is identified. Furthermore, a suitable pore range of 10.9%–30.3% is identified. Next step, the printed GDLs will undergo further testing to investigate their suitability to be used in PEM fuel cells.

Enhanced oil recovery via dissolution of low molecular weight PDMS in CO2 during immiscible gas injection in matrix-fracture system

Oil recovery in natural fracture reservoirs can be improved by reducing the capillary force during the gravity drainage process in matrix-fracture system. In the current study, a modified gas was generated via dissolution of low molecular weight poly(dimethyl siloxane) (PDMS, average Mw 3780 g/mol, 10000 – 50000 ppm) in CO2 to enhance oil recovery at 50 °C or 70 °C and 3000 psi. Cloud point measurements indicated that PDMS dissolved in CO2 at pressures less than 3000 psi, which was below the minimum miscibility pressure (MMP) of ∼3600 psi at 70 °C determined with the vanishing interfacial technique. The solution density increased from 669.6 kg/m3 for pure CO2 to 780.3 kg/m3 for CO2/PDMS (50000 ppm) at 70 °C and 3000 psi, thereby reducing the density difference between the CO2-rich fluid and crude oil (ρo=865.2 kg/m3) in matrix-fracture system. Also, CO2-oil interfacial tension (IFT) was reduced from 65 to 15 dyn/cm via the dissolution of 50000 ppm PDMS in CO2. Therefore, it led to the CO2 diffusion coefficient increased in both reservoir-fluid saturated porous media and bulk oil scenarios 3–4 fold and 4–7 fold respectively in comparison to pure CO2 injection. These PDMS-induced changes reduced the capillary effects in gas-invaded zone, which consequently led to an increase in oil recovery of 25% points (from 31% to 56%) compared to pure CO2 injection in the case of capillary continuity during gravity drainage tests. For the field-scale, because the PDMS can dissolve in CO2 at pressures and temperatures which are commensurate with CO2 EOR, it is a promising CO2-philic chemical for increasing CO2 density and improving CO2 diffusion coefficient in gas invaded zone compared to conventional CO2 injection.

Simulating Water and Salt Migration through Soils with a Clay Layer and Subsurface Pipe Drainage System at Different Depths Using the DRAINMOD-S Model

Soil salinization affects more than 25% of land globally. Subsurface pipe drainage is known for its effectiveness in improving saline–alkali land. The red clay layer (RCL) hinders soil improvement in the Hetao Irrigation District of Inner Mongolia, China. The soil water and salt migration rules at different buried depths and RCL were studied based on the field subsurface pipe drainage test and simulation using the DRAINMOD-S model (Version 6.1). The following implications can be drawn from the results: (1) Although the RCL affected the accuracy of the model, the calibrated statistical results met the application requirements, and the DRAINMOD-S model can be used to analyze subsurface pipe drainage under different distribution conditions of the RCL. (2) The RCL can reduce the drainage efficiency of the subsurface pipe, specifically when the distribution is shallow. (3) The soil desalting rate increased with an increase in the buried depth of the subsurface pipe. The desalination effect of shallow soil was better than that of deep soil. The RCL reduced the drainage and salt removal efficiency of the subsurface pipe. Burying the subsurface pipe as far above the RCL as possible should be considered. Thus, it is feasible to apply the DRAINMOD-S model to relevant studies.

Experimental study on the sound of water flowing through a storm drain

In buildings where storm drains are installed indoors, the sound of running water radiated from the surface of storm drains during rainfall may raise the noise level in rooms near the drain. To take appropriate measures against such sound according to the required quietness for the room, quantitative data on the sound of running water from storm drains is necessary, but few studies have dealt with this kind of sound. Therefore, the authors conducted experiments in an existing building, a drainage test tower, and a reverberation room to understand the characteristics of the sound produced by storm drains. Based on the results obtained through these experiments, this paper presents the effects of flow rate, pipe diameter, pipe material, and horizontal piping on the sound of running water from storm drains. The paper also discusses the differences between the sound generated by storm drains and the sound generated by sanitary sewers.

Effect of alkali-treated bamboo fibers on the properties of asphalt mixture

ABSTRACT Bamboo fiber is a natural fiber that is ecologically beneficial and one of the best materials to replace lignin fiber for roads, which is still difficult to utilize properly in asphalt mixtures owing to its poor adherence, dispersion, and hydrophilicity. Previous research has discovered that alkali treatment, as an effective treatment approach, may effectively lower the hydrophilicity of plant fibers and improve their compatibility with the matrix. As a result, it is vital to investigate the effect of alkali treatment on bamboo fibers used in asphalt mixtures. The composition and microstructure of bamboo fibers treated with alkali were investigated using SEM and FTIR methods, while the adhesion between the bamboo fiber and asphalt before and after alkali treatment was tested using the fiber pull-out test. In addition, the dispersion rate of bamboo fibers in asphalt mixture was determined by developing a connection equation using the Schellenberg binder drainage test. The performance of bamboo fiber asphalt mixtures was then evaluated using rutting tests, beam bending tests, immersion Marshall tests, freeze-thaw splitting tests, and cyclic fatigue testing. The results showed that the alkali treatment successfully eliminated impurities in the outer layer of the bamboo fibers and reduced their hydrophilicity, which enhanced the asphalt-bamboo fiber interactions as well as the asphalt mixture’s water damage resistance, specifically manifested as the residual stability of ABM was enhanced by 7.8% and the splitting tensile strength of ABM was raised by 12.2%. Furthermore, the surface polarity of the bamboo fibers was reduced, which weakened the agglomeration phenomenon and increases the dispersion rate of bamboo fibers in the mixture by 9%, efficiently improving the low-temperature cracking resistance and fatigue performance of asphalt mixtures.

Influence of SiO2 nanoparticles and Fe3O4 solution on the consolidation of geological soft soil

Soft soil is widely distributed in coastal areas and needs to be treated first when used as a foundation. A method of incorporating nano SiO2 particles and nano Fe3O4 solution is proposed to address the consolidation problem of geological soft soil. During the process, nanomaterials are selected and a preparation method for incorporating nanomaterial soil is designed. Subsequently, the experimental device is designed and the main instrument usage methods are specified, resulting in a complete experimental process design. The experimental results showed that in the generation of electron microscope images of soil, the soil mixed with nano SiO2 particles or nano Fe3O4 solution has a denser characterization; In the experiment of current variation in soil, the maximum current of the soil mixed with nano SiO2 particles is 0.1052 A at 72 hours; In the soil drainage test, the maximum total drainage of the soil mixed with nano Fe3O4 material at the end reached 1907 mL; In the soil pH value experiment, the pH value of the soil is higher when the proportion of nano SiO2 material added is 3‰ and the proportion of nano Fe3O4 material added is 2‰. The above results indicate that the geological soft soil consolidation method designed by the research institute incorporating nano SiO2 materials or nano Fe3O4 materials can effectively improve the drainage and mechanical properties of the soil.

Simulation of Salt Transport in Saline-alkali Soil under Different Control Modes

In order to ascertain the difference in the improvement effects of the two modes of water storage and drainage on saline-alkali soil. The method of simulating test plots was adopted to establish a closed water storage test area and an opened drainage test area. The interannual dynamic characteristics of soil salinity at different levels are analyzed. [Results] Under the water storage mode and drainage mode, the salt content of 0-100 cm soil was in a downward leaching migration state. Under the water storage mode and drainage mode, the soil salinity of each layer showed a trend of first decreasing and then increasing from 2015 to 2019. The horizontal migration of soil salinity in the water storage mode is mainly the interannual circular migration from the far end of the pool to the end of the near pool and then to the end of the far pool. The horizontal movement of soil salt in drainage mode is mainly one-way movement from the far end of the pool to the near end of the pool.

Construction and mechanism study of clean N2 foam fracturing fluid stabilized by viscoelastic surfactant in concentrated brines for unconventional oil and gas

As a much-anticipated clean thickener, viscoelastic surfactants (VESs) have drawn much attention in the development of foam fracturing fluids for unconventional oil and gas stimulation. Herein, the mechanism of foam stabilization by VESs and wormlike micelles (WLMs) under a high-salinity environment was investigated by evaluating three kinds of salt-tolerant VESs with different molecular structures through a series of experiments, including drainage tests, foam microscopic characteristic observations and interface rheology tests. The drainage test proved that the liquid film drainage was effectively inhibited under the proper salinity range for WLM construction. Based on microscopic observation, although WLMs are formed, gas diffusion inevitably occurs in each foam fluid as bubble size diversity exists, while the foam stabilized by VES-BC, the Gemini structure with steric hindrance on its spacer, exhibits comparably high uniformity of bubble size. Relying on the Gibbs criterion, this further proves that the foam stabilized by VES-BC resists gas diffusion better than the other two foams, as the critical shrinking speed of the VES-BC solution droplet to resist gas diffusion is lowest, which explains why the foam stabilized by VES-BC exhibits the best anti-coarsening capacity under static conditions. The oscillation droplet test proves that the VES-BC molecules and WLMs they construct impart the interface with the best resistance to external disturbance and deformation under the proper salinity range for WLM construction. Meanwhile, the interface shear modulus measurement indicates that the WLMs construed by VES-BC molecules and the interaction between WLMs and the VESs on the interface play crucial roles in anti-coalescence between bubbles. Under high-temperature and high-pressure conditions, the VES-C and VES-BC foam fracturing fluids prepared by brines, with 80% foam quality, both exhibit excellent thickening and proppant carrying capacity, and the VES-BC foam fracturing fluid can withstand 140 °C to sustain a low settling rate of proppant, which potentially decreases the cost of cleaning fracturing fluid by displacing 80% of the fluid into N2 and causes little damage to unconventional reservoirs. All experiments prove that foam coarsening is the key factor causing foam decay regardless of whether WLMs exist, yet WLMs can efficiently inhibit the drainage of liquid film and resist bubble coalescence by interacting with the molecules on the interface.

A Coupled Poro-Elastic Fluid Flow Simulator for Naturally Fractured Reservoirs

Naturally fractured reservoirs are characterized by their complex nature due to the existence of natural fractures and fissures within the rock formations. These fractures can significantly impact the flow of fluids within the reservoir, making it difficult to predict and manage production. Therefore, efficient production from such reservoirs requires a deep understanding of the flow behavior via the integration of various geological, geophysical, and engineering data. Additionally, advanced simulation models can be used to predict reservoir behavior under different production scenarios and aid in decision making and effective management. Accordingly, this study presents a robust mathematical two-phase fluid flow model (FRACSIM) for the simulation of the flow behavior of naturally fractured reservoirs in a 3D space. The mathematical model is based on the finite element technique and implemented using the FORTRAN language within a poro-elastic framework. Fractures are represented by triangle elements, while tetrahedral elements represent the matrix. To optimize computational time, short to medium-length fractures adopt the permeability tensor approach, while large fractures are discretized explicitly. The governing equations for poro-elasticity are discretized in both space and time using a standard Galerkin-based finite element approach. The stability of the saturation equation solution is ensured via the application of the Galerkin discretization method. The 3D fracture model has been verified against Eclipse 100, a commercial software, via a well-test case study of a fractured basement reservoir to ensure its effectiveness. Additionally, the FRACSIM software successfully simulated a laboratory glass bead drainage test for two intersected fractures and accurately captured the flow pattern and cumulative production results. Furthermore, a sensitivity study of water injection using an inverted five-spot technique was tested on FRACSIM to assess the productivity of drilled wells in complex fractured reservoirs. The results indicate that FRACSIM can accurately predict flow behavior and subsequently be utilized to evaluate production performance in naturally fractured reservoirs.

Mechanisms and field application of in-situ heat injection-enhanced gas drainage

The low permeability of coal seams and strong adsorption of methane considerably inhibit gas drainage; thus, developing a method for efficient gas drainage is crucial. The heat injection-enhanced gas drainage tests were carried out in the laboratory and coal mine, and the gas drainage effect and mechanism of heat injection method were studied. Then, through numerical simulation, the gas production law of heat injection method was analyzed from the perspective of water and gas migration. Indoor experiments demonstrated that heat injection strengthened methane desorption and relieved the inhibitory effect of water on gas. The gas drainage effect of field tests was remarkable, and the gas concentration and daily gas production increased by over 10 and 100 times, respectively. During heat injection, water occupied the migration channel of gas, and the inhibition of water on gas was greater than the promotion of temperature, resulting in the reduction of gas production; After heat injection, high temperature promoted gas desorption and relieved the inhibition of water on gas, resulting in a significant increase in gas production. The gas production law obtained from the numerical simulation showed a high degree of consistency with field tests. The results can provide a reference for gas control.

Airworthiness Requirements for Drainage Ground Test of Flammable Liquids from Transport Aircraft

The leakage and ignition of flammable liquids such as fuel and hydraulic liquid on transport aircraft are extremely harmful to aircraft and passengers. The drainage design is an effective means to reduce the probability of ignition and the resultant hazards if ignition does occur. The drainage test is required to show compliance with Article 25.863, and the drainage ground test must be performed before the flight test. This paper deeply studies Draft AC 25.863 and gives the airworthiness requirements for the drainage ground test of flammable liquids in combination with model practice. It provides a reference for the ground drainage compliance verification in the flammable liquid leakage area of transport aircraft.

The comparison of 7.5 and 15% hydrogen peroxide as oxidizing agent in static tests of acid mine drainage potential in Indonesia

Static tests of acid mine drainage potential are an important part of mining water management. Net acid generation (NAG) test is widely used in Indonesian coal mines because of its convenience. This test uses H2O2 to oxidize sulfide minerals within rock samples to determine their net acid-forming capacity. This study aimed to determine the difference between H2O2 at concentrations of 7.5% (the standard in several Indonesian coal mines) and 15% (the standard of the Acid Rock Drainage Test Handbook and Indonesian National Standard) in categorizing rocks as potentially acid-forming and non-acid-forming and in terms of NAG solution characteristics. A total of 564 rock samples collected from two Indonesian coal mining sites were analyzed using pH, NAG, total sulfur, and acid-base-accounting tests. The results of the study showed that there was no significant difference in rock classification or the behavior of contaminants in the NAG solution between 7.5% and 15% H2O2. The characteristics of sulfide minerals in Indonesian coal mines were the main factors influencing the results of the NAG test and behavior of contaminants in the NAG solution. Therefore, H2O2 at a concentration of 7.5% can be used in Indonesian coal mines with relatively low total sulfur concentrations (<5%) and minerals in framboidal form.

#4460 SEDIMENT IN CLEAR AND CLOUDY URINE: CAN INTERMITTENT CATHETERS DRAIN IT?

Abstract Background and Aims This study characterised the types and size of sediment in clear and cloudy urine and subsequently investigated the ability of conventional eyelet intermittent catheters and a novel Micro-hole Zone catheter to drain them. Method Clear urine was collected from three clinical studies where subjects drained with the conventional eyelet catheter and two prototypes of the Micro-hole Zone catheter. The studies included 60 subjects, equally distributed between male and female, healthy volunteers and intermittent catheterisation users. The sediment in the samples was analysed via automated microscopy (oCelloscope). Cloudy urine was collected from patients during their visits at the Urology Department of Rigshospitalet, Denmark. The samples were collected after spontaneous voiding, or via a conventional eyelet catheter and were analysed with the oCelloscope. An in vitro drainage test with the two catheters was subsequently performed. Results The analysis of clear urine (n = 180) showed most sediment to be smaller than 50 μm, with the largest sediment up to 200 μm (2.05 to 195.76 μm). The sediment included primarily crystals, cells, and bacteria, in line with published literature. Cloudy urine was divided into two categories, based on the presence of large particles visible to the naked eye. The samples without visible particles (n = 4) contained sediment with a mean size 12.81±0.038 μm (2.75 to 131.71 μm). The sediment identity corresponded to the sediment in clear urine, but the quantity was higher. Visible particles could not be analysed in the oCelloscope due to lack of light diffraction. These particles were soft and in various shapes and sizes. The Micro-hole Zone catheter drained sediment of larger size in clear urine compared to the conventional eyelet catheter. Both catheters drained cloudy urine efficiently but had challenges draining samples with visible particles (n = 20); the Micro-hole Zone catheter drained 12 samples, either directly or after light wiggling, while the conventional eyelet catheter drained 18 of the samples. Conclusion The analysis showed that the type of sediment does not differ between clear and cloudy urine without visible particles, but it is rather the abundance of sediment that induces the non-transparent appearance. The sediment was smaller than the size of the micro-holes (400 μm), therefore the novel catheter could efficiently drain urine and sediment and even larger size sediment. The latter could be explained by the design of the Micro-hole Zone, that allows urine and sediment to be drained continuously through a larger area, starting below the catheter tip, and extending to the bottom of the bladder neck. However, larger particles visible to the naked eye posed a challenge for the micro-holes and, to a lesser extent, to the conventional eyelets. Therefore, the number and size of visible particles should be considered when deciding on the appropriate bladder management option. However, only 20 such samples were procured, likely reflecting that such sediment is a rare occurrence in clinical practice