El Repositorio de Preprints de la Universidad de Concepción es una base de datos que reúne y preserva la producción de artículos de investigación científica generados dentro de la Institución antes de ser publicados en una revista. Este repositorio ha sido implementado en el marco del Proyecto InES de Ciencia Abierta INCA 210004 "Ciencia Abierta en la Universidad de Concepción: Creando Cultura y Democratizando la Ciencia", Objetivo 3: Fortalecer la gestión y articulación institucional en ciencia abierta por medio de la instalación de competencias, específicamente componentes de acceso, gestión a la información científica y acceso a datos de investigación. Cuenta con una plataforma tecnológica que permite integrar, organizar, gestionar y conservar la producción de documentos digitales que se generen en la Universidad, utilizando el sistema de código abierto Open Preprint Systems (OPS), desarrollado por el Public Knowledge Project (PKP), también responsable del Open Journal Systems (OJS). Estos procesos serán administrados por la Unidad de Apoyo a la Investigación, Dirección de Bibliotecas de la Universidad de Concepción. Su implementación está regulada por estándares internacionales que facilitan su interoperabilidad. Esta cualidad permite el intercambio de contenidos e información, convirtiéndose en un medio institucional de participación en repositorios académicos o institucionales de carácter nacional e internacional. De esta forma el repositorio contribuye al posicionamiento de la Universidad en el ámbito de las instituciones de educación superior.
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A comprehensive review of treatment technologies for greywater contaminants:
Serie: CRHIAM Categorías: CRHIAM Palabras clave: graywater, reuse, micropollutants, toxicity, removal mechanisms, case studies, linear alkyl benzene sulfonate Surfactants are considered a key pollutant in greywater (GW). However, there is no consensus on the best technologies for their removal. This review provides a comprehensive analysis of the main lines of GW research. Recent literature on GW characteristics, surfactant characteristics, toxicity and treatment technologies are analyzed along with case studies of GW reuse. The bibliometric analysis shows that 69% of the studies on GW involve surfactants, and physicochemical technologies predominate with 13.5% of the total studies. However, the toxicity of surfactants has been scarcely addressed (10% of the articles). Anionic surfactants represent 60% of the world production of surfactants. Concentrations in GW range from 7 to 436 mg/L and their toxicity measured as lethal concentration 50 (LC50) varies between 0.027-92 mg/L. Physicochemical treatments show a removal efficiency between 22-99% of anionic surfactants, while biological and advanced systems show between 53-99% removal efficiency. Furthermore, combined treatments show removal efficiencies between 78-99%. However, high costs of advanced systems limit their application on a large scale. In this sense, low-cost alternatives such as the use of reused adsorbent materials, natural solutions and disinfection systems could offer up to 98% surfactant removal. Regarding effluent toxicity, more research is needed, since limited studies address this gap. Moreover, it is unclear whether there will be a synergistic or antagonistic effect on the toxicity caused by surfactants and other pollutants on organisms and species. Along with this, the study of surfactant transformation products by different technologies and their toxicity is presented as a new research gap.
Derechos de autor 2026 Yennifer González, Valentina Carrillo, Gloria Gómez, Marta Carballa, Gladys Vidal https://creativecommons.org/licenses/by/4.0
Effects of combined antibiotics on the biomass stability and the occurrence of antibiotic-resistant bacteria in activated sludge used for domestic wastewater treatment
Serie: CRHIAM Categorías: CRHIAM Palabras clave: antibiotics, antibiotic-resistant bacteria, activated sludge biomass, respirometry, kinetic parameters The main objective of this study was to evaluate the effects of combined antibiotics on biomass stability and the occurrence of antibiotic-resistant bacteria (ARB) in activated sludge(AS) used for domestic wastewater treatment. Two aerobic lab-scale reactors were operated: one for the experimental approach (R1) and the other as a control (R2). In R1, two exposures were conducted with combined antibiotics of amoxicillin (AMX), ciprofloxacin (CIP) and ceftriaxone (CTX) at concentrations of 32, 4, and 2 μg/L, respectively, during exposure 1 (E1), and 64, 8, and 4 μg/L, respectively, during exposure 2 (E2). In these cases, removal efficiencies, oxygen uptake rate (OUR), specific oxygen uptake rate (SOUR) and ARB occurrences were evaluated. Within the results of this study, a significant effect on the AS biomass in terms of performance and kinetic parameters was observed with values below 10%, 20 mgO2/L·d and 100 mgO2/gVSS·d for organic matter removals, OUR and SOUR, respectively, during E1. However, during E2, AS biomass performances and kinetic parameters improved, with a 50% increase in these values. Moreover, ARB occurrences were only detected during E2, with abundances between 6.6 – 8.2 x102 CFU/mL. These findings suggest that the re-expose of AS biomass to combined antibiotic concentrations induced bacterial adaptation to this selective pressure resulting in the recovery of the heterotrophic activity and improved removal efficiency.
Derechos de autor 2026 Josefina Burgos, Gloria Gómez, Ana María Leiva, Gladys Vidal https://creativecommons.org/licenses/by/4.0
Performance of full-scale rural wastewater treatment plants in the reduction of antibiotic-resistant bacteria and antibiotic resistance genes from small-city effluents
Serie: CRHIAM Categorías: CRHIAM Palabras clave: antibiotic-resistant bacteria, antibiotic resistance genes, biological treatment, water quality parameters, principal component analysis, disinfection The main objective of this study was to evaluate the performance of full-scale rural wastewater treatment plants (WWTPs) in the reduction of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from small-city effluents. Twenty full-scale WWTPs in rural Chile with different biological treatment technologies (vermifiltration (VF), activated sludge (AS) and biodisc (BD)) and disinfection treatments (chlorination (Cl) and UV irradiation (UV)) were monitored and studied in two campaigns: Campaign 1 (20 WWTPs) and Campaign 2 (6 WWTPs). In both campaigns, the rural WWTPs improved the water quality of the effluents very significantly (90%, 70%, and 40% reductions in TU, COD, and NH4+-N, respectively) and reduced ARB and ARG loads by 2 to 4 log units. All three biological treatments contributed to the final quality of the effluents, especially in terms of microbiological parameters, with statistically indistinguishable efficiencies between them. These results show the importance of rural WWTPs in improving the water quality of urban effluents while reducing microbiological risk and the spread of antibiotic resistance into the environment. The study demonstrates the utility of a non-centralized, self-managed wastewater treatment scheme that can be implemented in many sparsely populated areas around the world.
Derechos de autor 2026 Ana María Leiva, Gloria Gómez, Gladys Vidal, Gerardo González Rocha, Benjamín Piña https://creativecommons.org/licenses/by/4.0
Phosphorus recovery from domestic wastewater:
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Phosphorus, Recovery, Recycling, Legislation, Wastewater, Institutional framework Phosphorus (P) is an essential element for life that must be managed sustainably. The institutional framework for P recovery from wastewater includes policies, regulations, plans, and actions that promote the recovery, recycling, and safe use of this element, aimed at moving toward more sustainable nutrient management and environmental protection. This review analyzes the status of the institutional framework for P recovery from wastewater in different countries around the world. Europe is the continent where the most progress has been made in terms of legislation. Countries such as Germany, the Netherlands, Austria, and Denmark have already implemented policies and regulations that promote environmental protection, as well as P recovery and reuse. In other parts of the world, such as the United States, China, and Japan, there have also been significant advances in promoting the closure of the P cycle, with the implementation of advanced recovery technologies in wastewater treatment plants and regional/national action plans. By contrast, in Latin America there has been little progress in P treatment and recovery, with a weak regulatory framework, unclear goals, and insufficient allocation of techno-economic resources. In this context, it is necessary to reinforce the comprehensive institutional framework, which covers technological aspects, economic incentives, political agreements, and regulations, to promote the sustainable management of this valuable resource.
Derechos de autor 2026 Gladys Vidal, Valentina Carrillo, Rodrigo Castillo, Albert Magri, Eduardo Holzapfel https://creativecommons.org/licenses/by/4.0
Understanding hydrological dynamics in Andean basins:
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Semi-arid, Andean range, groundwater exfiltration, tritium, Stable isotope Mountain ranges cover approximately 24% of the Earth's land mass. These environments have a special relevance in terms of global water supply. However, historically mountain groundwater processes have been generally overlooked or poorly understood, especially in the Andes cordillera. With this in mind, this work aimed to study hydrological processes in four Andean, semi-arid headwater river basins. Along with monthly stable isotope data collection, we carried out a synoptic surface water sampling program in each river on four specific dates for 3H analysis. The latter indicated water of similar age in the rivers of three sub-basins (Derecho, Cochiguaz, Incaguaz), but much older in the fourth (Toro). We assessed different possible explanations for these differences such as effects of past mining activities (El Indio mine), physiographic factors, and snow accumulation and glacier related factors, but none of these were satisfactory. Instead, our findings point to the activation of faults in response to seismic activity, which induces pumping of fluids (water) from deeper zones, facilitating exfiltration processes in the Toro River sub-basin. This explains the presence of surface waters older than those associated with current meteoric processes. Such geological process should be assessed and eventually accounted for when studying mountain hydrogeological processes, especially in high fractured areas with direct or indirect evidence of geothermal activity.
Derechos de autor 2026 José Luis Arumi, Ricardo Oyarzún, Denisse Duhalde, Jan Boll, Shelley MacDonell https://creativecommons.org/licenses/by/4.0
Well-balanced physics-based finite volume schemes for Saint-Venant-Exner-type models of sediment transport
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Finite volume method, depth-averaged model, well-balanced methods, sediment transport The Saint-Venant-Exner (SVE) model is widely used for the description of sediment transport including bedload, erosion, and deposition processes. A modified version of the SVE model, which includes sediment concentration incorporates exchange of sediment between the fluid and an erodible bed and a non-hydrostatic pressure for the fluid along with non-equilibrium entrainment and deposition velocities, is introduced. Gravitational effects on erosion are described by an effective shear stress formulation. This modified SVE model is derived from a general approach with density variations. It preserves the mass of both the sediment and the fluid, and satisfies a dissipative energy balance. On the other hand, well-balanced finite volume schemes adapted for SVE models are derived since standard well-balanced schemes for the Saint-Venant system with fixed bottom are in general no more well-balanced when applied to the SVE model. The latter property is due to the uncontrolled numerical diffusion associated with the bed evolution equation. Two novel techniques to achieve the well-balanced property for the modified SVE model are proposed. The first is a new polynomial-viscosity-matrix-based (PVM) scheme, denoted “PVM-2I”, that modifies the numerical approximation of the bed evolution equation according to its related characteristic speed. The second is a physically motivated correction of the numerical diffusion term for the Rusanov and Harten-Lax-van Leer (HLL) schemes. The proposed schemes are positivity-preserving for the water height. Numerical solutions are compared with exact solutions with gravitational effects, with a novel exact solution in non-equilibrium conditions, and with experimental data. It is illustrated how the use of standard non-well-balanced schemes leads to a large artificial (unphysical) erosion and completely degraded solutions. This undesirable behaviour is avoided by the proposed well-balanced schemes.
Derechos de autor 2026 Raimund Bürger, Enrique D. Fernández Nieto, José Garres Díaz, Jorge Moya https://creativecommons.org/licenses/by/4.0
Thickening mechanism under high compression stress based on rheological properties: Comparison between compression effect and compression-shear coupling effect
Serie: CRHIAM Categorías: CRHIAM Palabras clave: High compression stress, Compression-shear coupling effect, Double yield stress, Concentration, Thickening mechanism Tailings thickening is the primary link and key technology of cemented paste backfill (CPB) technology. However, the concentration of thickened tailings often is substandard because of the unclear of thickening mechanism. Therefore, this paper inveterated the thickening mechanism based on the rheological properties of tailings. Firstly, the double yield stress (compressive and shear yield stress) and concentration evolution under compression and compression-shear coupling effects were tested, respectively. And then the correlation analysis between concentration and double yield stress was carried out. The concentration shows a power function of the double yield stress, and shear yield stress is a linear function of the compressive yield stress. It is found that the linear fitting proportional coefficients under the compression effect are lower than those under the compression-shear coupling effect. The full compression stress range is divided into the low and high compression stress ranges and the shear yield stress-compressive yield stress proportional coefficients in the two compression stress ranges are linearly fitted. It is found that the proportional coefficients in the low compression stress range are lower than those in the high compression stress range under the compression effect, but the opposite results are shown under the compression-shear coupling effect, which shows that the introduction of rake-shearing action by the compression-shear coupling effect mainly improves the thickening rate and the thickening effect in the low compression stress range. Moreover, by introducing the rake-shearing action, the concentration growth ratio also confirms that the compression-shear coupling effect improves the thickening effect in the low compression stress range. Furthermore, from the evolution offloc structure and drainage channels, the thickening mechanism of the compression effect and compression-shear coupling effect was revealed. The results are beneficial for obtaining a satisfied underflow concentration in CPB.
Derechos de autor 2026 Raimund Bürger, Aixiang Wu, Zhenqi Wang, Zhuen Ruan, Shaoyong Wang, Yi Mo https://creativecommons.org/licenses/by/4.0
Quantitative analysis of static yield stress variation in thickened tailings in compaction zone based on fine structure
Serie: CRHIAM Categorías: CRHIAM Palabras clave: tailings thickening, static yield stress, particle gradation, pore network model In the tailings thickening process, the poor flowability of the high concentration tailings slurry is likely to cause slurry hardening at the bottom of the vertical sand silo and rake blockage of the thickening machine, which will hurt the safe production of the mine and pollutes the environment. Therefore, the effect of slurry concentration on the static yield stress of the slurry with and without shear conditions was investigated using the full tailings of iron ore as raw material in this study. A comparative analysis of the static yield stress of thickened tailings and fresh mixing slurry with the same concentration and particle gradation was completed. The fine structural parameters of the thickening bed with and without shear were obtained by computed tomography. The effects of the structural parameters of the drainage channels in the thickening bed and the changes in the content of coarse particles with diameters ranging from 45 300 μm on the porosity of the thickening bed were analyzed. The effect of the fluctuation of the thickening bed's porosity on the slurry's static yield stress was also investigated. The results show that the thickened tailings is non homogeneous. The concentration of the slurry, the number and volume of coarse particles with diameters in the range of 75 300 μm increases with decreasing bed height. Analysis of the pore network model based on the structural equivalents of the drainage channels revealed that the pore volumes with equivalent diameters in the range of 50 250 μm are the largest and are the main storage space for water in the bed. Compared with the spherical pore structure, the stick throat channel structure is the main component of the drainage channel structure in the bed. The slurry rheology measurements show that the static yield stress of the thickened tailings is 5.3 61.3 times higher than the static yield stress of the fresh mixing slurry for the same slurry concentration and particle gradation. Our analyses revealed that the fluctuation of the porosity of the slurry also has an essential effect on the static yield stress of the thickened tailings. For the first time, we propose to use the coefficient of variation in bed porosity to quantify the difference in static yield stress values between thickened tailings and fresh mixing slurry and draw the necessary conclusion that the static yield stress of slurry decreases with the reduction of the coefficient of variation in bed porosity under the same conditions of slurry concentration and particle gradation. Based on the results of our research, it was applied in an iron ore mine in China, where vertical sand silo was used as the thickening equipment to solve the problem of slurry hardening in the silo and to achieve safe and efficient filling production.
Derechos de autor 2026 Gezhong Chen, Cuiping Li, Zhuen Ruan, Raimund Bürger, Bingheng Yan, Chen Hu, Xue Li https://creativecommons.org/licenses/by/4.0
Interaction of jamitons in second-order macroscopic traffic models
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Traffic flow, jamitons, stability, collision Jamitons are self-sustained traveling wave solutions that arise in certain second-order macroscopic models of vehicular traffic. A necessary condition for a jamiton to appear is that the local traffic density breaks the so-called sub-characteristic condition. This condition states that the characteristic velocity of the corresponding first-order Lighthill-Whitham-Richards (LWR) model formed with the same desired speed function is enclosed by the characteristic speeds of the corresponding second-order model. The phenomenon of collision of jamitons in second-order models of traffic flow is studied analytically and numerically for the particular case of the second-order Aw- Rascle-Zhang (ARZ) traffic model [A. Aw, M. Rascle, SIAM J. Appl. Math. 60 (2000) 916–938; H. M. Zhang, Transp. Res. B 36 (2002) 275–290]. A compatibility condition is first defined to select jamitons that can collide each other. The collision of jamitons produces a new jamiton with a velocity different from the initial ones. It is observed that the exit velocities smooth out the velocity of the test jamiton and the initial velocities of the jamitons that collide. Other properties such as the amplitude of the exit jamitons, lengths, and maximum density are also explored. In the cases of the amplitude and maximum exit density it turns out that over a wide range of sonic densities, the exit values exceed or equal the input values. On the other hand, the resulting jamiton has a greater length than the incoming ones. Finally, the behavior for various driver reaction times is explored. It is obtained that some properties do not depend on that time, such as the amplitude, exit velocity, or maximum density, while the exit length does depend on driver reaction time.
Derechos de autor 2026 Raimund Bürger, Claudio Muñoz, Sebastián Tapia https://creativecommons.org/licenses/by/4.0
AN ENTROPY STABLE AND WELL-BALANCED SCHEME FOR AN AUGMENTED BLOOD FLOW MODEL WITH VARIABLE GEOMETRICAL AND MECHANICAL PROPERTIES
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Augmented blood flow model, vessel with variable properties, well-balanced scheme, entropy stable scheme The flow of blood through a vessel can be described by a hyperbolic system of balance equations for the cross-sectional area and averaged velocity as functions of axial spatial position and time. The variable arterial wall rigidity and the equilibrium cross sectional area are incorporated within the so-called tube law that gives rise to an internal pressure term. This system can be written as a conservative hyperbolic system for five unknowns. An entropy stable scheme for this augmented one-dimensional blood flow model is developed based on entropy conservative numerical flux. It is proved that the proposed scheme is well balanced in the sense that it preserves both trivial (zero velocity) and non-trivial (non-zero velocity) steady-state solutions. Several demanding numerical tests show that the scheme can handle various kinds of shocks and preserves stationary solutions when geometrical and mechanical properties of the vessel are variable.
Derechos de autor 2026 Raimund Bürger, Andrés Guerra, Carlos Vega https://creativecommons.org/licenses/by/4.0
A MULTILAYER SHALLOW WATER MODEL FOR TSUNAMIS AND COASTAL FOREST INTERACTION
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Finite volume method, layer averaged non-hydrostatic approach, multilayer model, coastal forest, Tsunami mitigation Models and numerical methods of the impact of tsunamis on coastal forests are of vital importance for exploring the potential of coastal vegetation as a means of mitigation. Such a model is formulated as a multilayer shallow water system based on a free-surface formulation of the Euler equations for an ideal fluid. Specifically, the Euler equations are approximated by a layer averaged non-hydrostatic (LDNH) approach involving linear pressures and piecewise constant velocities. Furthermore, based on [K. Iimura and N. Tanaka, Numerical simulation estimating effects of tree density distribution in coastal forest on tsunami mitigation, Ocean Engrg. 54 (2012) 223–232] drag forces, inertia forces, and porosity are added to model the interaction with the forest. These ingredients are specified in a layer-wise manner. Thus, the vertical features of the forest are described with higher accuracy than within a single-layer approach. Projection methods for the non-hydrostatic pressure in conjunction with polynomial viscosity matrix finite volume methods [M. J. Castro and E. Fern´andez-Nieto, A class of computationally fast first order finite volume solvers: PVM methods. SIAM J. Sci. Comput. 34 (2012) A2173–A2196] are employed for the numerical solution of the multilayer model,that is for the propagation of tsunamis and coastal flooding. Experimental observations and field data are used to validate the model. In general good agreement is obtained. Results indicate, moreover, that coastal vegetation can operate as an efficient natural barrier against coastal hazards and can significantly reduce the effects of tsunamis.
Derechos de autor 2026 Raimund Bürger, Enrique D. Fernández Nieto, Jorge Moya https://creativecommons.org/licenses/by/4.0
Front tracking and parameter identification for a conservation law with a space-dependent coefficient modeling granular segregation
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Granular media, segregation, conservation law, discontinuous flux, front tracking method, parameter identification A well-known experimental setup for the study of segregation by sizein a dry granular medium consists of two layers of spheres composed of large and small rigid spheres. These layers are contained within an annular region of concentric cylinders covered above and below by plates. One of the cylinders is rotated and thereby applies shear to the granular mixture. The spheres will then mix and the large ones rise while the small ones settle in vertical direction. This phenomenon can be modelled by a conservation law whose flux involves a piecewise constant or smooth coefficient [L. May, M. Shearer, and K. Daniels, J. Nonlin. Sci., 20 (2010), pp. 689–707] that describes dependence of the shear rate on depth. This model is solved by the hyperfast front tracking method adapted to a conservation law with discontinuous flux. In this way the coefficient can efficiently be identified from experimental observations. Numerical examples are presented.
Derechos de autor 2026 Raimund Bürger, Yessennia Martínez, Luis M. Villada https://creativecommons.org/licenses/by/4.0
Revealing the influence of additional structure on the flow field characteristics in feedwell through PIV experiments
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Thickener feedwell, Particle image velocimetry, Additional structure, Flow field Cemented paste backfill (CPB) is a widely used method for resource utilization of tailings. The thickener feedwell is the key equipment for CPB in realizing solid-liquid separation. Flocculation is a significant process in treating tailings slurry thickening and dehydration. To reveal the flow field variation in the flocculation process, a range of feedwell with the additional structure were devised, containing the guide chute feedwell, the guide shelf feedwell, and the no-additional structure feedwell. To this purpose, the effects of hydrodynamics on flocculation performance in the feedwell were investigated with particle image velocimetry (PIV). The velocity and energy distribution were used to describe the variation of the flow field. The size and fractal dimension of aggregates for the flocculation reaction in the feedwell were studied. Furthermore, the turbidity was compared to evaluate the flocculation performance of these feedwells. The results of the PIV experiments indicated that the additional structure can effectively improve flocculation performance, ultimately achieving efficient solid-liquid separation efficiency. The flocculation process in the feedwell incorporates the mixing-collision section, and the settling-growth section along the flow direction, with bounding by additional structure. The ideal high-efficiency feedwell is to produce a symmetrical and uniform flow field, providing matched shear strength for the two flocculation sections. The guide shelf feedwell exhibited superior performance, resulting in significantly larger aggregate sizes while also experiencing remarkable compactness compared to the alternative additional structure. The reason is that the tailings slurry and flocculant obtain high mixing intensity and residence time in the mixing-collision section, causing the effective collision of micro aggregates, further increasing their size and compactness in the settling-growth section. Meanwhile, the gradually decaying energy distribution avoids fragmentation of the aggregates. This work is expected to provide the theoretical basis and technical support for the design and optimization of the feedwell, finally achieving deep dewatering and reducing solid waste pollution in mines.
Derechos de autor 2026 Pengjie Wu, Aixiang Wu, Zhuen Ruan, Raimund Bürger, Shaoyong Wang, Chong Chen, Zhenqi Wang https://creativecommons.org/licenses/by/4.0
Flocculation behavior, mechanism, and optimization of tailings based on RSM-BBD-DF: Insight into the concentration and time-dependent floc size
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Mean weighted chord length, Concentration, Time-dependent, Response Surface Methodology-Box-Behnken Design-Desirability function 44 (RSM-BBD-DF), Multi-objective optimization Tailings thickening is the primary link and key technology of cemented paste backfill (CPB) technology, in which flocculation conditions are important factors affecting thickening effect. Conventional flocculation effects only consider macro indexes such as concentration and initial settling rate (ISR), ignoring the floc evolution. In this study, the multi-objective optimization of flocculation effect based on Response Surface Methodology-Box-Behnken Design-Desirability Function (RSM-BBD-DF) was carried out. Firstly, through the single-factor experiments, the sedimentation properties and floc size evolution under different influencing factors were analyzed. It is found that the evolution of floc size is time-dependent, which conforms to the Asym2sig model, and there is a linear relationship between test-ending floc size and ISR. The larger the floc, the higher the ISR. Through the RSM-BBD, the regression models of concentration and mean weighted chord length (MWCL) as response values were established. Multi-factor interaction found that the tailing feeding concentration (TFC) had the greatest influence on the concentration, and the shear rate (SR) had the greatest influence on the MWCL. The interaction between TFC and the flocculant solution concentration (FSC) has the highest influence on the concentration. The interaction between TFC and SR has the highest influence on the MWCL. By introducing the single Desirability Function and the overall Desirability Function, the optimization method based on RSM37 BBD-DF obtained the optimal flocculation conditions, which were very close to the optimization results of Design Expert, indicating that RSM-BBD-DF optimization method is reliable. Thus, RSM-BBD-DF has important application value for multi-objective optimization in mining and other industries.
Response Surface Methodology-Box-Behnken Design-Desirability function 44 (RSM-BBD-DF)
Derechos de autor 2026 Raimund Bürger, Zhenqi Wang, Aixiang Wu, Zhuen Ruan, Shaoyong Wang, Yi Mo https://creativecommons.org/licenses/by/4.0
Higher-order conservative discretizations on arbitrarily varying non-uniform grids
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Finite volume method, finite difference scheme, conservative discretization, WENO, ENO Conservative discretizations of transport equations are based on integral formulationsthat include the finite volume method (FVM) and conservative finite difference methods (CFDMs). The FVM is used by most fluid dynamics simulation packages and require ssmoothly shifting grids for better convergence. This motivates the study of the order of accuracy and rate of convergence of the FVM on non-uniform grids. It is difficult to do such an analysis of the FVM on an unstructured grid; however, the FVM is reduced to a CFDM on a Cartesian grid. The effect of the order of accuracy and the rate of convergence of higher-order CFDMs on arbitrarily varying grids is therefore investigated. It is shown that higher-order conservative discretizations on arbitrarily varying non-uniform grids are not even first-order accurate in theoretical and numerical test cases. This property is verified by a symbolic computation procedure. If the grid is replaced by a gradually varying grid, it is shown that conservative discretizations yield a better rate of convergence. In this situation a rate of convergence between one and the theoretical maximum can be achieved in dependence of the grid stretch/- contraction ratio. Numerical examples including the linear convectionm-diffusiom equation, the lid-driven cavity problem, and the Taylor-Green vortex problem are presented.
Derechos de autor 2026 A. Arun Govind Neelan, Raimund Bürger, Manoj T. Nair, Samala Rathan https://creativecommons.org/licenses/by/4.0
Developing a new permeability model of the compressible tailings thickening bed based on the pore network structure parameter
Serie: CRHIAM Categorías: CRHIAM Palabras clave: tailings thickening, thickening bed, pore network model, permeability In the tailings thickening process, the low concentration tailings slurry is separated by solid liquid separation forming a compressible tailing thickening bed structure at the bottom of the thickener This structure provide s a high concentration filling slurry for mine paste backfilling production. Microstructure study of the compressible tailing s thickening bed and analysis of its permeability is essential for preparing high concentration filling slurry and ensuring stable equipment operation. In this study, we employ ed computer tomography to obtain the pore structure of the compressible tailings thickening bed at different pressures with and without shear. We analyzed the evolution of the compressible tailings thickening bed pore structure under mechanical action based on the pore network model (PNM). P ermeability simu lation experiments of the compressible tailings thickening bed structure were conducted to obtain the permeability evolution trend. Based on the PNM model of the compressible tailings thickening bed pore structure and the research on the thickening bed per meability, a new quantitative index Tw was proposed, and a new permeability model was constructed considering the throat structure parameters. Three empirical models were used to predict the compressible tailings thickening bed permeability and were compa red with the simulation results and the new model. The results indicate that the compressible tailings thickening bed porosity decrease with increas ing thickening bed pressure, which reduces the permeability of the compressible tailings thickening bed structure while increasing the concentration of the thickening bed slurry. In c ompar ison to without shear, rake shear action caused forced damage to the compressible tailings thickening bed pore structure, forcing further discharge of fluid in the tailings thi ckening bed structure, resulting in an additional increase in tailings thickening bed slurry concentration and a fur ther decrease in permeability. The diameter of the spherical pores and the diameter and length of the stick throat in the compressible tailings thickening bed structure all decrease with the increas e in the thickening bed pressure. Fluid in the compressible tailings thickening bed structure primarily discharged to the top of the thickening bed through the throat structure in the PNM model, and the compressible tailings thickening bed structure permeability decreases with increasing Tw value of the throat. The new model proposed in this study, considering the throat structure parameter Tw , is more accurate in predicting the compressible tailings thickening bed permeability compared to the empirical model.
Derechos de autor 2026 Gezhong Chen, Cuiping Li, Zhuen Ruan, Raimund Bürger, Hezi Hou https://creativecommons.org/licenses/by/4.0
Enhancing Evapotranspiration Estimates in Orchards with the Surface Energy Balance for Partially Vegetated surfaces (SEB-PV) 12 Model through Combined Use of Gridded Soil Moisture and Temporal Upscaling Methods
Serie: CRHIAM Categorías: CRHIAM Palabras clave: agricultural water management, hazelnut, pistachio, satellite soil moisture products, SMAP, surface energy balance, temporal extrapolation The Surface Energy Balance for Partially Vegetated surfaces (SEB-PV)model provides accurate evapotranspiration (ET) estimates for orchard crops. However, it faces two operational limitations: requiring specific input data unavailable from conventional agro-meteorological stations and lacking an evidence-based algorithm for upscaling instantaneous ET to daily values. This study addresses these limitations by evaluating SEB-PV performanee under three conditions: 1) using measured soil moisture with in situ meteorological equipment; 2) using gridded soil moisture products (Climate Forecast System and Soil Moisture Active Passive) with in-situ meteorological equipment; 3) using gridded soil moisture products with agro-meteorological stations' data. Seven temporal upscaling methods were compared for ET estimation in commercially-produced, micro-irrigated hazelnut (Chile) and pistachio (California) orchards. A Model Decision Making Indicator (MDMI), combining Kling-Gupta efficiency and normalized root mean square error (NRMSE), is proposed to enhance parameter optimization sensitivity. SEB-PV performance using gridded soil moisture products demonstrated comparable accuracy to configurations using measured soil moisture after parameter adjustment (MDMI values > 70 for hazelnuts, NRMSE ~ 21%; >59 for pistachios, NRMSE ~ 29%). Transitioning from in-situ meteorological measurements to agro-meteorological stations minimally impacted hazelnut orchards but required careful consideration for pistachios. Methods that up-scale instantaneous ET to daily values on the basis of net radiation performed optimally for hazelnut orcharcls grown in Mecliterranean climatic conclitions (NRMSE ~ 15%), while meteorological inputs-based methods were preferable for semi-aricl pistachio orchards (NRMSE ~ 30%). These finclings show that SEB-PV can maintain acceptable accuracy using globally available datasets, improving operational applicability through guidance for input selection and temporal upscaling tailored to orchard characteristics.
Derechos de autor 2026 Lorenzo E. Cigarra Guíñes, Octavio Lagos, Pasquale Steduto, Sebastián A. Krogh, Kristen Shapiro, Camilo Souto, Mario Lillo Saavedra, Claudia Balbontín, Daniele Zaccaria https://creativecommons.org/licenses/by/4.0
A review of the application of the discrete element method in comminution
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Discrete element method, DEM Disciplina(s): Ingeniería The discrete element method (DEM) has been widely used in process modeling in industry. The ability to represent comminution techniques has been essential in the mineral processing industry and other sectors where rock size reduction is a fundamental aspect. With the need for more accurate and advanced models, the application of computational approaches has initiated the resolution of complex challenges in the comminution process. This article provides a comprehensive review of the application of the Discrete Element Method in several critical aspects of the mineral processing industry, focusing on the modeling of comminution equipment, screens, and transfer chutes between 2014 and 2024. Comminution, an essential process in mineral processing, is discussed in detail, highlighting the importance of optimizing performance and energy efficiency at each stage, from crushing to grinding. The central role of DEM in overcoming the limitations of empirical models is highlighted, providing a more advanced and accurate approach to predicting operational parameters and equipment wear rates. Finally, possible paths and perspectives for applying DEM in mining equipment are highlighted, addressing pending challenges and seeking solutions to emerging problems in this field.
Derechos de autor 2026 Patricio Toledo, Manuel Moncada, Fernando Betancourt, Cristóbal Ruiz, Cristian G. Rodríguez C., Cristián Vicuña https://creativecommons.org/licenses/by/4.0
COUPLED FINITE VOLUME METHODS FOR SETTLING IN INCLINED VESSELS WITH NATURAL CONVECTION
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Sedimentation, natural convention, Boycott effect, numerical simulation, lamella settler A widely applied technology of gravity-driven solid-liquid separation in mineral processing is the use of lamella settlers. These units are continuously operated tanks equipped with a number of parallel inclined plates immersed in the mixture to be separated. The inclination of the plates exploits the well-known Boycott effect that describes the enhancement of settling rates beneath inclined surfaces. This effect is usually attributed to a rapidly upward-streaming layer of clear liquid. The essence of this effect can be studied by examining gravity settling in an inclined tube or rectangular channel. The lower and upper surfaces of the channel represent the plate onto which the particles start to settle and below which the clarified liquid streams upward, respectively. In addition an increase of temperature in some part of the fluid causes a local change in the density of the fluid and circulation of the fluid within the vessel. It has been proposed to exploit this behaviour to accelerate the settling process by additional heating. To examine this hypothesis a model and corresponding numerical method to describe inclined settling enhanced by natural convection are formulated. The model consists in a two-dimensional scalar conservation law for the solids concentration coupled with a version of the Stokes system that accounts for density fluctuations in the mixture enhanced by a Boussinesq approximation of the effect of temperature. In addition a convection-diffusion equation describes heat transport and diffusion. The main outcome is a numerical method that allows one to simulate the effect of controllable parameters such as the initial concentration, difference of temperature, and angle of inclination on the progress of the solid-liquid separation. Numerical examples are presented. Results reconfirm that the enhancement of settling rates depends critically on the dimensions of the settling vessel, intensity of heating, and particle size, and is marginal for settling of relatively large particles and channels with a moderate length to width aspect ratio.
Derechos de autor 2026 Fernando Betancourt, Raimund Bürger, Julio Careaga, Lucas Romero https://creativecommons.org/licenses/by/4.0
Modeling of a laboratory cone crusher using the discrete element method
Serie: CRHIAM Categorías: CRHIAM Palabras clave: cone crusher Comminution consists of the progressive reduction of ore size in successive stages. This process is the most energy-consuming in mining, utilizing up to 50% of the total energy used in mineral processing Jeswiet and Szekeres(2016). Among the challenges that this process presents are the inappropriate design of the process control, unwanted segregation and ore variability from Run-of-Mine Asbjörnsson et al. (2022). Therefore, there is growing demand to optimize the performance and profitability of comminution circuits (Bengtsson et al., 2017). This demand has generated a high interest in the modeling and simulation of mining processes, with the aim of achieving the prediction of different operating parameters of different equipment Johansson et al. (2017). The prediction of the behavior of these machines is possible using mathematical models, which can be classified into empirical (Bearman et al., 1991) and mechanistic models (Liu et al., 2018; Evertsson,1999). Some of the latter can be solved numerically, such as those developed using the discrete element method. With the discrete element method, several mining machines have been simulated (Weerasekara et al., 2013).
Derechos de autor 2026 Fernando Betancourt, Manuel Moncada, Patricio Toledo, Cristian Rodriguez https://creativecommons.org/licenses/by/4.0
Experimental investigations on sustainable mortar containing mining tailing as partial replacement of fine aggregate
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Concrete, Copper Tailing, Replacement, Mechanical resistance, Chemical Characterisation Mine tailings, originating from diverse regions in central Chile (Andina, Los Bronces, El Teniente), were systematically collected and subjected to mineralogical analysis. Based on this analysis, the tailings were categorized into distinct minerals groups, including silicate, carbonate, and feldspar. Following this categorization, these mine tailings were explored as promising substitutes for fine aggregates in concrete constituents. It was found a substantial enhancement in the compressive strength of concrete when incorporating mine tailings, particularly when replacing up to 30% of the fine aggregates. This improvement can be initially attributed to the presence of heavy metals within the tailings. However, exceeding the 30% threshold for fine aggregate replacement with tailings, results in a diminishing effect on concrete compressive strength. The favourable outcomes can be attributed to the mineralogical compositions of the tailings, particularly to the SiO2 content, which exerts a positive influence on the overall matrix mix.. This innovative approach not only augments the performance of concrete but also contributes to a noteworthy reduction in the environmental footprint associated with mining activities.
Derechos de autor 2026 Siva Avudaiappan, Rene Gómez, Fernando Betancourt, Cristián Canales Cardenas, Manuel Chávez https://creativecommons.org/licenses/by/4.0
Role of mountain glaciers in the hydrological dynamics of headwater basins in the Wet Andes
Serie: CRHIAM Categorías: CRHIAM Palabras clave: Wet Andes, Mountain basins, Stable isotope, Glacier melt, Mixing model The Andes of southern Chile have isolated glaciers on volcanic edifices that, together with the precipitation, contribute to several important river systems in the region. The decrease in the extension of glaciers and the negative trend in precipitation will reduce the downstream water availability. Nonetheless, studies on the sensitivity of hydrological systems due to climate change focus mainly on arid and semi-arid areas of the Andes, compared to wet regions with isolated mountain glaciers. Despite the extension and hydrological importance of the Wet Andes and significant trends of decreasing flow that have affected the region for several years, studies have yet to assess the importance of its glaciers in runoff generation. Through isotopic monitoring, we estimate the contribution of glacial melt in the Allipen headwater basin of the Wet Andes (between 38°40’S and 39°S). We performed isotopic measurements of 18O and 2H on a seasonal basis during three seasons in snow, glacial melt, lagoons, groundwater, and stream flow in nested basins. Stable isotope data were analyzed in a Bayesian framework using the MixSIAR model, where spatial and temporal relationships were incorporated. The contribution of groundwater (springs) is prominent in three of the four nested basins throughout the analyzed period. In one of the basins, lagoons correspond to the main contributing source. Additionally, the contribution of glacier thaw reached up to 30% in another of the nested basins. Meanwhile, precipitation was less important in all basins. When analyzing the complete basin (without the nested basin approach), the results show the dominance of groundwater contributions as the main source, varying between 56% and 62%, followed by ponds, which vary between 13.5% and 23%. In contrast, glacier thaw varies between 11% and 18%, even though it only covers approximately 1.5% of the total basin area. These results show the variability of hydrological processes at different spatial scales and the importance of small mountain glaciers in the basins of the Wet Andes. Furthermore,the analysis of the physical variables of the basins allows for identifying the importance of the volcanic landscape in the hydrological dynamics of the region. Our results suggest that due to climate change, it is necessary to evaluate and quantify changes in flow dynamics in humid regions, especially in basins that receive significant contributions from retreating glaciers. These results will allow for the identification of new monitoring points and techniques to discriminate and quantify the contribution of different sources and the identification of areas or hydrological processes relevant in terms of conservation or integrated management.
Derechos de autor 2026 Elizabet Lizama, Marcelo Somos-Valenzuela, Diego Rivera, Mario Lillo, Bastian Morales, Michel Baraër, Alonzo Fernandez https://creativecommons.org/licenses/by/4.0
Evaluation of the Effect of a 'Serious Game' on Cardiopulmonary Resuscitation in Reinforcing Knowledge and Confidence among Medical Students at Universidad de Concepción
Serie: Preprints Palabras clave: Serious game, Cardiopulmonary resuscitation (CPR), Medical Education, Educational Technologies Cardiorespiratory arrest is one of the most severe health emergencies a person can face, and cardiopulmonary resuscitation (CPR) is the most effective intervention to reverse this condition. However, the effectiveness of CPR largely depends on how quickly and accurately the maneuvers are performed.This study analyzed the impact of using a "serious game" to support the reinforcement of knowledge and confidence in cardiopulmonary resuscitation (CPR) among second year medical students at Universidad de Concepción. Using a quasi-experimental design, an experimental group that used the serious game was compared with a control group that did not receive this intervention. The study assessed knowledge and confidence before and after the intervention through questionnaires and Likert scales. The results indicate that students in the experimental group showed significant improvements in both knowledge and confidence in performing these maneuvers. However, no significant difference was observed when comparing both groups (p > 0.05). These results may be explained by the high level of prior knowledge students possessed before the intervention, due to specific subjects taken previously. Nonetheless, this does not imply that the serious game lacks educational value. It is possible that its impact could be more evident among students with lower prior knowledge or in different educational contexts, such as students from other degree programs or the general population.
Derechos de autor 2025 Juan Olivos Pérez, Juan Francisco Hernández Quidel, Carolina Fernández Chavez, Eugenio Chandia Muñoz, Sofia Klein Diaz, Graciela Sandoval Martinez https://creativecommons.org/licenses/by/4.0
Interaction of Val66Met BDNF and 5-1 HTTLPR polymorphisms with prevalence of post2 earthquake 27-F PTSD in Chilean population
Serie: Preprints Palabras clave: Child Maltreatment, Earthquake, Tsunami, Posttraumatic stress disorder, Depresive episode Disciplina(s): Medicina Abstract Natural disasters can have significant impacts on populations, including an increased risk of developing post-traumatic stress disorder (PTSD). This study aimed to investigate the prevalence of PTSD in individuals who had previously undergone structured psychiatric diagnostic interviews in the aftermath of the 27-F earthquake in Chile. The prevalence of post-earthquake PTSD was found to be 11.06%, with no significant difference from the reported prevalence of PTSD in those exposed to traumatic events. While studies have identified higher rates of PTSD in women, this study did not find any sex related differences. However, a concomitant diagnosis of depressive episodes (DE) was significantly associated with an elevated risk of developing post earthquake PTSD. Witnessing more than one critical traumatic event associated with the earthquake was also found to escalate the risk of developing earthquake-induced PTSD. The study also evaluated the potential influence of genetic factors on the risk of post-earthquake PTSD. The presence of BDNF and 5-HTTLPR genetic variants was assessed, and although studies have proposed that carriers of the Met allele are more susceptible to developing PTSD, this study did not identify a significant association between the Met allele and the incidence of post-earthquake PTSD. Similarly, while studies have suggested that individuals carrying at least one "S" allele of 5-HTTLPR are more susceptible to stress-related disorders, this study did not find a significant association between the LG and S alleles and the incidence of post-earthquake PTSD. The study highlights the need for clinical care to prioritize the detection and treatment of concomitant DE and the exposure to critical traumatic events in survivors of disasters. Early interventions can potentially mitigate the risk of developing post-disaster PTSD. Furthermore, the study suggests a need for a more comprehensive understanding of genetic predispositions to post-disaster PTSD, and future research is encouraged to explore other genetic variants that could influence the development of PTSD. Limitations of the study include the potential interference of different DE subtypes, the complexity of quantifying the degree of earthquake exposure experienced by each individual, and events entailing social disruption, such as looting, that can profoundly influence distress. These limitations highlight the need for further research to broaden the understanding of PTSD following disasters, potentially leading to more effective prevention and treatment strategies. In conclusion, this study emphasizes the multifaceted nature of PTSD and the significant role that critical traumatic experiences and concomitant depressive episodes play in the development of postdisaster PTSD. The study provides insights into potential areas for intervention and highlights the need for further research to better understand the relationship between genetic factors and post-disaster PTSD.
Derechos de autor 2023 Juan Luis Castillo Navarrete, Benjamín Vicente, Kristin Schmidt, Esteban Moraga Escobar, Romina Rojas Ponce, Paola Lagos, Ximena Macaya, Alejandra Guzmán Castillo https://creativecommons.org/licenses/by/4.0