Performance Evaluation of Two Series Vertical Flow Filters for Wastewater Treatment: A Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

This paper evaluates the efficacy of two sequential vertical flow filters (VFF), FV1 and FV2, implanted with Typha, in a pilot-scale wastewater treatment system. FV1 comprises three cells (FV1a, FV1b, and FV1c), while FV2 consists of two cells (FV2a and FV2b), each designed to reduce various physicochemical and microbiological pollutants from wastewater. Quantitative analyses show significant reductions in electrical conductivity (from 1331 to 1061 μS/cm), biochemical oxygen demand (BOD5 from 655.6 to 2.3 mg/L), chemical oxygen demand (COD from 1240 to 82.2 mg/L), total nitrogen (from 188 to 37.3 mg/L), and phosphates (from 70.9 to 14.6 mg/L). Notably, FV2 outperforms FV1, particularly in decreasing dissolved salts and BOD5 to remarkably low levels. Microbiological assessments reveal a substantial reduction in fecal coliforms, from an initial concentration of 7.5 log CFU/100mL to 3.7 log CFU/100mL, and a complete elimination of helminth eggs, achieving a 100% reduction rate in FV2. The study highlights the impact of design parameters, such as filter material, media depth, and plant species selection, on treatment outcomes. The findings suggest that the judicious choice of these components is critical for optimizing pollutant removal. For instance, different filtration materials show varying efficacies, with silex plus river gravel in FV1c achieving superior pollutant reduction rates. In conclusion, VFFs emerge as a promising solution for wastewater treatment, underscoring the importance of design optimization to enhance system efficiency. Continuous monitoring and adaptation of treatment practices are imperative to ensure water quality, allowing for safe environmental discharge or water reuse. The research advocates for ongoing improvements in wastewater treatment technologies, considering the environmental challenges of the current era. The study concludes with a call for further research to maximize the effectiveness of VFFs in water management.

Performance of a Horizontal Flow Constructed Reed Bed Filter for Municipal Wastewater Treatment: The Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.

On the effect of pitch and yaw angles in oblique impacts of smallcaliber projectiles

A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study.The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea? software yielded the conclusions.The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile’s core.The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results.An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study.The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile’s performance.

Lateral ring compression test applied to a small caliber steel jacket:Identification of a constitutive model

The evolution of threats and scenarios requires continuous performance improvements of ballistic protections for armed forces.From a modeling point of view,it is necessary to use sufficiently precise material behavior models to accurately describe the phenomena observed during the impact of a projectile on a protective equipment.In this context,the goal of this paper is to characterize the behavior of a small caliber steel jacket by combining experimental and numerical approaches.The experimental method is based on the lateral compression of ring specimens directly machined from the thin and small ammunition.Various speeds and temperatures are considered in a quasi-static regime in order to reveal the strain rate and temperature dependencies of the tested material.The Finite Element Updating Method(FEMU)is used.Experimental results are coupled with an inverse optimization method and a finite element numerical model in order to determine the parameters of a constitutive model representative of the jacket material.Predictions of the present model are verified against experimental results and a parametric study as well as a discussion on the identified material parameters are proposed.The results indicate that the strain hardening parameter can be neglected and the behavior of the thin steel jacket can be described by a modeling without strain hardening sensitivity.

Adaptive optimisation of explosive reactive armour for protection against kinetic energy and shaped charge threats

We evaluate an adaptive optimisation methodology,Bayesian optimisation(BO),for designing a minimum weight explosive reactive armour(ERA)for protection against a surrogate medium calibre kinetic energy(KE)long rod projectile and surrogate shaped charge(SC)warhead.We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert.A third approach,utilising a novel human-machine teaming framework for BO is also evaluated.Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments.The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations,outperforming both the stand-alone human and stand-alone BO methodologies.From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples.

Characterization of Wastewater in School Environments for an Ecological Treatment Solution: A Case Study of Ndiebene Gandiol 1 School

The study conducted at Ndiebene Gandiol 1 school in Senegal has unveiled serious environmental and public health challenges. The wastewater analysis revealed high levels of Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and fecal coliforms, signaling potential risks to the well-being of students and staff. This situation mirrors a wider issue in rural educational settings, where inadequate sanitation persists. Intensive wastewater treatment options are known for their effectiveness against high pollutant loads but are resource-intensive in both energy and cost. Conversely, extensive treatment systems, while requiring more land, provide a sustainable alternative by harnessing natural processes for pollutant removal. The research suggests a hybrid treatment approach could serve the school’s needs, balancing the robust capabilities of intensive methods with the ecological benefits of extensive systems. Such a solution would need to be tailored to the specific environmental, financial, and logistical context of the school, based on comprehensive feasibility studies and stakeholder engagement. This study’s findings underscore the urgency of addressing sanitation in schools, as it is intrinsically linked to the health and academic success of students. Quick, effective, and long-term strategies are vital to secure a healthier and more prosperous future for the youth. With proper implementation, the school can transform its sanitation facilities, setting a precedent for rural educational institutions in Senegal and similar contexts globally.

Design and Sizing of an Ecological Wastewater Treatment System in a School Environment: A Case Study of Ndiebene Gandiol 1 School

The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO2/day and COD of 12.8775 kgO2/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m2, divided into two cells of 108.58 m2 each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.

Ecological Wastewater Treatment System Using a Horizontal Flow Biological Reactor: The Case of Vetiver

Confronted with the challenge of wastewater management, particularly in the school environment of Senegal, our study set out to achieve multiple objectives. Following field surveys, laboratory analyses of wastewater samples were carried out, revealing a significant pollutant load. In the community of Gandiol, near Saint-Louis (Senegal), the school of Ndiebene Gandiol 1 faces significant sanitation challenges. Our study aimed to address this issue by using a constructed filter composed of two filtering bed cells measuring 12 × 8.5 m, preceded by a septic tank. We particularly focused on the influence of Vetiver;a plant chosen for its purification potential. Our analyses showed remarkable efficiency of the filter. Elimination rates reached 95% for 5-Day Biochemical Oxygen Demand (BOD5), 91% for Chemical Oxygen Demand (COD), and 92% for SS, far exceeding the Senegalese standards set at 50 mg/L, 200 mg/L, and 40 mg/L, respectively. Furthermore, the concentration of fecal coliforms was reduced to 176 FCU/100mL, well below the Senegalese threshold of 2000 FCU/100mL and close to the World Health Organization’s (WHO) recommendation of 1000 FCU/100mL. However, despite these promising results, some parameters, particularly the concentration of certain pollutants, approached the thresholds defined by European legislation. For example, for Suspended Solids (SS), the post-treatment level of 3 mg/L was well below the Senegalese standard but edged close to the European minimum of 10 mg/L. In conclusion, the Vetiver filter demonstrated a remarkable ability to treat school wastewater, offering high pollutant elimination percentages. These results suggest significant opportunities for the reuse of treated water, potentially in areas such as irrigation, though some adjustments may be necessary to meet the strictest standards such as those of the European union (EU).

A Comparative Analysis of Vetiver and Typha in Ecological Wastewater Treatment Using a Horizontal Flow Constructed Wetlands in Rural Setting

This study presents an assessment of wastewater ecological treatment processes utilizing a horizontal flow bio-reactor at the Ndiebene Gandiol 1 school. It primarily aims to juxtapose the filtration efficacy of two distinct vegetative cells, Vetiver and Typha, in the pursuit of sustainable wastewater management strategies for rural scholastic institutions. A synergistic approach was employed, integrating on-site surveys for site-specific insights and laboratory analyses to quantify the pollutant loads pre- and post-treatment. Our findings indicate that both Vetiver and Typha-infused filter beds significantly reduce most contaminants, with particular success in diminishing chemical oxygen demand (COD) and biological oxygen demand (BOD5). Vetiver was notable for its superior reduction of COD, achieving an average effluent concentration of 74 mg/L, in contrast to Typha’s 155 mg/L. Conversely, Typha excelled in suspended solids removal, registering 1 mg/L against Vetiver’s 3 mg/L. While both systems notably surpassed the target metrics across several indicators, including fecal coliform reduction, our results pinpoint the need for refinement in phosphate remediation. Conclusively, the study underscores the efficacy of both Vetiver and Typha systems in rural wastewater treatment contexts, with their integrative application potentially paving the way for enhanced system robustness and efficiency. The outcomes herein highlight the imperative for continued research to further hone these ecological treatment modalities, especially concerning phosphate elimination.

Reconstruction of the Unsteady Supersonic Flow around a Spike Using the Colored Background Oriented Schlieren Technique

In this paper, the improved Background Oriented Schlieren technique called CBOS (Colored Background Oriented Schlieren) is described and used to reconstruct the density fields of three-dimensional flows. The Background Oriented Schlieren technique (BOS) allows the measurement of the light deflection caused by density gradients in a compressible flow. For this purpose the distortion of the image of a background pattern observed through the flow is used. In order to increase the performance of the conventional Background Oriented Schlieren technique, the monochromatic background is replaced by a colored dot pattern. The different colors are treated separately using suitable correlation algorithms. Therefore, the precision and the spatial resolution can be highly increased. Furthermore a special arrangement of the different colored dot patterns in the background allows astigmatism in the region with high density gradients to be overcome. For the first time an algebraic reconstruction technique (ART) is then used to reconstruct the density field of unsteady flows around a spike-tipped model from CBOS measurements. The obtained images reveal the interaction between the free-stream flow and the high-pressure region in front of the model, which leads to large-scale instabilities in the flow.

Formation mechanisms of sub-micron pharmaceutical composite particles derived from far-and near-field Raman microscopy

Surface enhanced Raman spectroscopy(SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particles produced by spray flash evaporation(SFE). Morphology, size and crystallinity of furosemide/PVP particles are analyzed by scanning electron microscopy(SEM) and X-ray powder diffraction(XRPD). Far-field Raman spectra and confocal far-field Raman maps of furosemide/PVP particles are interpreted based on the far-field Raman spectra of pure furosemide and PVP precursors.Confocal far-field Raman microscopy shows that furosemide/PVP particles feature an intermixture of furosemide and PVP molecules at the sub-micron scale. SERS and surface-enhanced confocal Raman microscopy(SECo RM) are performed on furosemide, PVP and furosemide/PVP composite particles sputtered with silver(40 nm). SERS and SECo RM maps reveal that furosemide/PVP particle surfaces mainly consist of PVP molecules. The combination of surface and bulk sensitive analyses reveal that furosemide/PVP sub-micron particles are formed by the agglomeration of primary furosemide nanocrystals embedded in a thin PVP matrix. Interestingly, both far-field Raman microscopy and SECo RM provide molecular information on a statistically-relevant amount of sub-micron particles in a single microscopic map;this combination is thus an effective and time-saving tool for investigating organic sub-micron composites.

Blast disruption using 3D grids/perforated plates for vehicle protection

In this work, blast disruption and mitigation using 3D grids/perforated plates were tested for underbelly and side protection of vehicles. Two vehicle simulants were used: a small-scale one for side vehicle protection assessment and a true-to-scale simulant for underbelly protection testing. The deformation of target plates was assessed. These were either unprotected or protected by three different types of disruptors. The first disruptor was made of a sandwich structure of two perforated plates filled with a thin aluminum structure allowing the air to pass through. The two other disruptors were made of pieces of cast metallic foam. Two different kinds of foams were used: one with large cells and the second one with small cells. Beforehand, the mitigation efficiency of the disruptors was evaluated using an explosivedriven shock tube(EDST). The experiments showed that blast disruption/mitigation by 3D grid/perforated plate structures was not suitable for vehicle side protection. However, 3D grids/perforated structures proved to be relatively effective for underbelly protection compared to an equivalent mass of steel.

Data-driven prediction of plate velocities and plate deformation of explosive reactive armor

Explosive reactive armor(ERA)is currently being actively developed as a protective system for mobile devices against ballistic threats such as kinetic energy penetrators and shaped-charge jets.Considering mobility,the aim is to design a protection system with a minimal amount of required mass.The efficiency of an ERA is sensitive to the impact position and the timing of the detonation.Therefore,different designs have to be tested for several impact scenarios to identify the best design.Since analytical models are not predicting the behavior of the ERA accurately enough and experiments,as well as numerical simulations,are too time-consuming,a data-driven model to estimate the displacements and deformation of plates of an ERA system is proposed here.The ground truth for the artificial neural network(ANN)is numerical simulation results that are validated with experiments.The ANN approximates the plate positions for different materials,plate sizes,and detonation point positions with sufficient accuracy in real-time.In a future investigation,the results from the model can be used to estimate the interaction of the ERA with a given threat.Then,a measure for the effectiveness of an ERA can be calculated.Finally,an optimal ERA can be designed and analyzed for any possible impact scenario in negligible time.

Ballistic tests on hot-rolled Ti-6Al-4V plates:Experiments and numerical approaches

Superior ballistic performance and the lightweight character of Ti alloys are considered as main reasons for their use in armour applications against a broad spectrum of ballistic threats,e.g.bullet,fragment or blast impact.Because dynamic loading caused by typical penetrators is characterized by high strain rates,only specific test methods allow a closer investigation of the respective material behaviour.In the present study,quasi-static and dynamic compression tests as well as ballistic tests were conducted on a twophase a+βalloy Ti-6Al-4V(in m%)manufactured by hot-rolling.Post-deformation heat treatments,influencing microstructure and mechanical properties were applied in order to compare three different microstructural configurations:as-rolled,mill-annealed and bimodal.While,on the one hand,ballistic tests were employed for the determination of the ballistic limit velocity v_(50),compression tests,on the other hand,delivered essential input parameters for the application of the Johnson-Cook constitutive model in a finite element simulation of the impact event.The comparison of experimental results to simulation results was supplemented by means of microstructural characterization of tested samples with the focus set on the prevalently observed deformation and damage mechanisms,as for example adiabatic shearing.

Design of Fe(3–x)O4 raspberry decorated graphene nanocomposites with high performances in lithium-ion battery

Fe（3–x）O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery（LIB）. Indeed, Fe（3–x）O4 raspberry shaped nanostructures consist of original oriented aggregates of Fe（3–x）O4 magnetite nanocrystals, ensuring a low oxidation state of magnetite and a hollow and porous structure, which has been easily combined with graphene sheets. The resulting nanocomposite powder displays a very homogeneous spatial distribution of Fe（3–x）O4 nanostructures at the surface of the graphene sheets. These original nanostructures and their strong interaction with the graphene sheets resulted in very small capacity fading upon Li＋ion intercalation. Reversible capacity, as high as 660 m Ah/g, makes this material promising for anode in Li-ion batteries application.