Search Results (241)

This study compared the effectiveness of the Sequencing Batch Biofilter Granular Reactor (SBBGR) plant with and without the integration of ozone (BIO-CHEM process) in the remediation of medium-aged landfill leachate. Special attention is given to the removal of per- and polyfluoroalkyl substances (PFAS) as a group of bioaccumulative and persistent pollutants. The findings highlight the high SBBGR performance under biological process only for key wastewater contaminants, with 82% for chemical oxygen demand (COD), 86% for total nitrogen, and 98% for ammonia. Moderate removal was observed for total (TSS) and volatile (VSS) suspended solids (41% and 44%, respectively), while phosphorus and colour removal remained limited. Remarkably, the SBBGR process achieved complete removal of long-chain PFAS, while its performance declined for shorter-chain PFAS. BIO-CHEM process significantly improved COD (87.7%), TSS (84.6%), VSS (86.7%), and colour (92–96%) removal. Conversely, ozonation led to an unexpected increase in the concentrations of several PFAS in the effluent, suggesting ozone-induced desorption from the biomass. SBBGR treatment was characterised by a low specific sludge production (SSP) value, i.e., 5–6 times less than that of conventional biological processes. SSP was further reduced during the application of the BIO-CHEM process. A key finding of this study is a critical challenge for PFAS removal in this combined treatment approach, different from other ozone-based methods. Full article

Trustworthy product quality data forms the foundation of digital and distributed manufacturing, yet current centralized product quality management (PQM) systems remain vulnerable to data manipulation, traceability breaks, single points of failure, and related adverse effects. To clarify how blockchain can address these weaknesses, this paper presents a systematic review of blockchained product quality management (BPQM). Firstly, the paper groups the architectures and models related to BPQM and proposes an ISA 95-aligned reference framework that secures a real-time quality data exchange. Secondly, seven key BPQM enablers are analyzed, including (1) visual intelligence-based quality inspection, (2) cyber–physical twinning and parallel control of manufacturing systems, (3) blockchained agent modeling and secure data sharing, (4) multi-level blockchain mapping, (5) smart contract-based decentralized system configuration and operation, (6) artificial intelligence-based decentralized BPQM applications, and (7) traceability of process coordination and control. Thirdly, through analysis of social barriers and technological challenges, four research directions are identified, namely, (1) optimal granularity of data in system configuration; (2) smart contracts for self-organizing intelligence; (3) balancing system security, cost, and performance; and (4) interoperability and integration with legacy systems. It is expected that this paper lays a solid foundation for the practical use of blockchain in PQM engineering. Full article

Aerated accumulation bioreactors represent a promising alternative for the aerobic bioremediation of solid contaminated substrates. However, achieving homogeneous mixing and effective air distribution remains a key design challenge in solid-phase systems. This study presents the design and construction of a novel pilot-scale aerated bioreactor equipped with an angled-paddle agitation system, specifically developed to improve solid mixing and aeration. To evaluate the geometric configuration, a series of simulations were performed using the Discrete Element Method (DEM), with particle dynamics analyzed through the Lacey Mixing Index ($LMI$). Four paddle angles (0°, 15°, 45°, and 55°) were compared, with the 45° configuration achieving optimal performance, reaching $LMI$ values above 0.95 in less than 15 s and maintaining high homogeneity at a filling volume of 70%. These results confirm that the paddle angle significantly influences mixing efficiency in granular media. While this work focuses on engineering design and DEM-based validation, future studies will include experimental trials to evaluate biodegradation kinetics. The proposed design offers a scalable and adaptable solution for ex situ bioremediation applications. This work reinforces the value of integrating DEM simulations early in the bioreactor development process and opens pathways for further optimization and implementation in real-world environmental remediation scenarios. Full article

Poly[bis(4-phenyl) (2,5,6-trimethylphenyl) amine (PTAA), as a hole transfer material, has been widely used in perovskite solar cells (PSCs). However, the optimal solvent for preparing the PTAA solution and coating the PTAA layer is still uncertain. In this work, we investigated three types of organic solvents (toluene, chlorobenzene and dichlorobenzene) for processing PTAA layers as the hole transport layer in PSCs. Based on the experimental verification and molecular dynamics simulation results, all the evidence indicated that toluene performs best among the three candidates. This is attributed to the significant polarity difference between toluene and PTAA, which leads to the formation of a uniform surface morphology characterized by granular protuberances after spin coating. The contact area of the hole transfer layer with the surface aggregation is increased in reference to the rough surface, and the hydrophilicity of the PTAA layer is also increased. The improvement of these two aspects are conducive to the effective interfacial charge transfer. This leads to the generation of more photocurrent. The PSCs employing toluene-processed PTAA exhibit an average power conversion efficiency (PCE) of 19.1%, which is higher than that of PSCs using chlorobenzene- and dichlorobenzene-processed PTAA (17.3–17.9%). This work provides a direct optimization strategy for researchers aiming to fabricate PSCs based on PTAA as a hole transport layer and lays a solid foundation for the development of high-efficiency inverted PSCs. Full article

The widely utilized TiO₂ nanoparticles (NPs) tend to accumulate in wastewater and affect microbial growth. This work investigated the impacts of prolonged TiO₂ NP addition to filamentous aerobic granular sludge (AGS) using two identical sequencing batch reactors (SBRs, R1 and R2). R1 (the control) had no TiO₂ NP addition. In this reactor, filamentous bacteria from large AGS grew rapidly and extended outward, the sludge volume index (SVI₃₀) quickly increased from 41.2 to 236.8 mL/g, mixed liquid suspended solids (MLSS) decreased from 4.72 to 0.9 g/L, and AGS disintegrated on day 40. Meanwhile, the removal rates of COD and NH₄⁺-N both exhibited significant declines. In contrast, 5–30 mg/L TiO₂ NPs was added to R2 from day 21 to 100, and the extended filamentous bacteria were effectively controlled on day 90 under a 30 mg/L NP dosage, leading to significant reductions in COD and NH₄⁺-N capabilities, particularly the latter. Therefore, NP addition was stopped on day 101, and AGS became dominant in R2, with an SVI₃₀ and MLSS of 48.5 mL/g and 5.67 g/L on day 130. COD and NH₄⁺-N capabilities both increased to 100%. Microbial analysis suggested that the dominant filamentous bacteria—Proteobacteria, Bacteroidetes, and Acidobacteria—were effectively controlled by adding 30 mg/L TiO₂ NPs. XRF analysis indicated that 11.7% TiO₂ NP accumulation made the filamentous bacteria a framework for AGS recovery and operation without NPs. Functional analysis revealed that TiO₂ NPs had stronger inhibitory effects on nitrogen metabolism compared to carbon metabolism, and both metabolic pathways recovered when NP addition was discontinued in a timely manner. These findings offer critical operational guidance for maintaining the stable performance of filamentous AGS systems treating TiO₂ NP wastewater in the future. Full article

The accurate modeling of dynamic soil–structure interaction processes under impact loading is critical for advancing the design of soil-embedded barrier systems. Full-scale crash testing remains the benchmark for evaluating barrier performance; however, such tests are costly, logistically demanding, and subject to variability that limits repeatability. Recent advancements in computational methods, particularly the development of large-deformation numerical schemes, such as the multi-material arbitrary Lagrangian–Eulerian (MM-ALE) and smoothed particle hydrodynamics (SPH) approaches, offer viable alternatives for simulating soil behavior under impact loading. These methods have enabled a more realistic representation of granular soil dynamics, particularly that of the Manual for Assessing Safety Hardware (MASH) strong soil, a well-graded gravelly soil commonly used in crash testing of soil-embedded barriers and safety features. This soil exhibits complex mechanical responses governed by inter-particle friction, dilatancy, confining pressure, and moisture content. Nonetheless, the predictive fidelity of these simulations is governed by the selection and implementation of soil constitutive models, which must capture the nonlinear, dilatant, and pressure-sensitive behavior of granular materials under high strain rate loading. This review critically examines the theoretical foundations and practical applications of a range of soil constitutive models embedded in the LS-DYNA hydrocode, including elastic, elastoplastic, elasto-viscoplastic, and multi-yield surface formulations. Emphasis is placed on the unique behaviors of MASH strong soil, such as confining-pressure dependence, limited elastic range, and strong dilatancy, which must be accurately represented to model the soil’s transition between solid-like and fluid-like states during impact loading. This paper addresses existing gaps in the literature by offering a structured basis for selecting and evaluating constitutive models in simulations of high-energy vehicular impact events involving soil–structure systems. This framework supports researchers working to improve the numerical analysis of impact-induced responses in soil-embedded structural systems. Full article

This research explores the modification of marl by the incorporation of diopside (CaMgSi₂O₆) to develop a composite material with improved dielectric properties, while addressing environmental and economic challenges through the use of abundant natural resources. X-ray fluorescence (XRF) analysis reveals a high silicate content in the raw marl, mainly SiO₂ (68.12%) and Al₂O₃ (12.54%), while laser particle size analysis indicates a homogeneous grain size distribution centered around 100 µm. The composite was synthesized by the solid-state reaction method, achieving good phase homogeneity. X-ray diffraction (XRD) and infrared spectroscopy confirm the incorporation of diopside, while SEM analysis shows a porous morphology with granular aggregates. The modified material has an average particle size of 11.653 µm, optimizing the electrical properties. Impedance spectroscopy demonstrates improved dielectric performance, with accumulated permittivity and reduced losses, which improves energy storage and dissipation. Tests showed the remarkable stability of dielectric properties over a wide frequency range (10 Hz to 10 MHz) and low-temperature dependence. The performance was demonstrated on a single sample with a thickness of 0.63 mm, demonstrating consistent efficiency. These results position the diopside-modified marl as a promising candidate for electrochemical and microelectronic applications. Full article

Pulsed detonation–plasma technology (PDT) is a surface-modification technology used in an atmospheric environment, where plasma, a detonation impact and thermal conditions are combined and have an effect on the material’s surface. In this study, annealed 65Mn steel was selected to further study the principle of PDT modification. The results show that the modified layer with fine grains was divided into an infiltration layer with a large amount of non-uniformly distributed granular CW₃ carbides and a heat-affected layer below the infiltration layer after PDT treatment. However, a higher amount of acicular martensite and a lower amount of austenite was achieved in the modified layer, containing a large number of small-angle grain boundaries, dislocations, and twin grains. After the PDT treatment, the hardness of the modified layer, heat-affected layer, and substrate was 980 HV, 856.2 HV, and 250 HV, respectively. The mass loss of the sample before and after PDT treatment was 21.1 mg and 12.4 mg, respectively. The hardness and wear resistance of the modified layer were greatly improved compared with the substrate because of the combined effect of the solid-phase transformation, element infiltration, and distortion. Full article

In this work, a novel method for the disposal of ladle furnace slag (LFS) and soda residue (SR) was proposed. By applying geopolymer technology, LFS and SR were used as precursors to manufacture a geopolymer with sufficient fresh and mechanical properties that can be used in construction works, such as in non-structural components like lightweight partition walls. The effects of raw material ratios and Na₂O equivalents on the fresh properties, mechanical properties, microstructure and environmental impact of LFS-SR geopolymer (LSG) were analyzed by rheology, compressive strength, XRD, TG/DTG, SEM, and calculation of embodied carbon. The results showed that the compressive strength of LSGs increased when the SR content decreased or Na₂O equivalent increased, and the maximum compressive strength could reach 12.0 MPa at 28 d. The hydration products of LSG were mainly C-(A)-S-H gel, C₃AH₆, and AFt. Notably, the C-(A)-S-H gels formed a stable cross-linked structure, and the extremely fine granular C₃AH₆ further filled the pores. Furthermore, AFt was generated from the interaction between LFS and CaSO₄ rich in SR during the hydration process. The carbon calculation results indicated that the embodied carbon of LSGs was significantly lower than that of traditional cement, and the LSG containing 20% SR and 12% Na₂O equivalent had the highest sustainability. This study proposed strategies for mitigating the environmental hazards of alkaline solid waste and improving its resource utilization, thereby promoting sustainable development in the construction industry. Full article

The wettability of granular solids is a critical parameter in numerous industrial applications, including enhanced oil recovery, advanced material coatings, and nanotechnology. However, traditional methods for assessing wettability, such as contact angle measurements, face significant challenges when applied to heterogeneous or porous solids. This study proposes a rheological methodology as an alternative approach to determine the wettability of granular solids, focusing on bentonite clay modified via sodium dodecylbenzene sulfonate adsorption. Aqueous and oily suspensions of bentonite with varying degrees of hydrophobicity were characterized using viscosity measurements, oscillatory amplitude sweeps, and thixotropic recovery tests. For the system under study, a bentonite concentration of 8% ensures optimal rheological behavior. Furthermore, the adsorption isotherm provides a reliable means of determining varying degrees of solid coverage. The results demonstrated clear correlations between surface coverage and rheological behavior, with increasing hydrophobicity leading to reduced viscosity and viscoelasticity in aqueous systems and a shift toward Newtonian flow behavior in oily systems. These findings were supported by traditional contact angle measurements, which confirmed the relationship between surfactant adsorption and enhanced hydrophobicity. The proposed rheological methodology overcomes the limitations of conventional wettability assessments and provides a new approach for characterizing and optimizing the interfacial properties of particulate systems. This work has broad implications across industries such as petroleum, coatings, and material science, offering a novel pathway for designing systems with tailored wettability and flow characteristics. Full article

To address the failure issue of local wear in QT400-18 transition shafts used in high-speed trains, laser cladding remanufacturing of a ductile cast iron surface was carried out using 45 wt.%Fe + 55 wt.% Inconel625 powder. The phase composition, microhardness, interfacial bonding strength, and wear resistance of the cladding layer were analyzed. The results show that the cladding layer is primarily composed of a γ (Ni, Fe) solid solution and a small amount of eutectic carbides. The microstructure of the cladding layer forms columnar dendrites, cellular dendrites, and equiaxed crystals from bottom to top. The microstructure of the single-layer, single-pass interface consists of ferrite, acicular martensite, and ledeburite, while the multi-layer, multi-pass interface consists of ferrite, granular pearlite, and discontinuous ledeburite. The average microhardness of the single-layer, single-pass cladding layer is approximately 350 HV_0.5, and the hardness of the fine-grained and coarse-grained regions of the multi-layer, multi-pass cladding layer is approximately 330 HV_0.5 and 250 HV_0.5, respectively. The interfacial bonding strength reaches 96.5% of the base material strength. The wear mechanism of the cladding layer is mainly mild abrasive wear, with significantly better wear resistance than the base material. Full article

Thermal energy storage (TES) systems are essential components of concentrating solar power (CSP) plants that enable uniform generation of green electricity and process heat. The performance of sensible heat TES systems based on granular material and on solid blocks was experimentally analyzed during the discharge process. A granular material TES system was studied in its operation as a regular fluidized bed and as a confined bed that restricted the motion of the granular material via mechanical confinement. The pressure drop required to circulate the heat transfer fluid (HTF) through the TES system made of alumina blocks was measured to be two orders of magnitude lower than that used in the granular material TES system, being uniform and close to 0.2 bar for operation of the fluidized bed and decreasing from 0.65 to 0.3 bar for the confined bed. The evolution of the exergy efficiency of the TES systems along the discharge process was determined by obtaining an inversed exponential reduction for the fluidized bed TES system, a parabolic reduction for the alumina block TES system, and a roughly uniform value for the confined bed TES system. The exergy efficiency of the confined bed TES system, considering the HTF pressure drop as a parasitic consumption of the plant, remained higher than 90% during the complete discharge process. Full article

Fusion welding easily causes microstructural coarsening and tempering softening in the heat-affected zone (HAZ) of high-strength pipeline steel joints, which considerably deteriorates the strength and toughness. Here, X80 pipeline steel was subjected to friction stir welding (FSW), and external cooling was used to tailor the microstructure to optimize the strength–ductility combination of the nugget zone (NZ). Coarse granular bainite (GB) appeared at air cooling, whereas a fine ferrite/martensite microstructure was achieved at solid CO₂ cooling. The highest ratio of high-angle boundaries was obtained at solid CO₂ cooling because the variants were evenly distributed within the four close-packed (CP) groups. The low yield strength (YS) of 595 MPa was obtained in the NZ under air cooling, whereas a high YS of 755 MPa was achieved in the NZ under solid CO₂ cooling due to dislocation strengthening and fine-grain strengthening. Furthermore, an ultra-high tensile strength of 910 MPa and utilizable elongation of 15% were obtained in the NZ under solid CO₂ cooling, which was attributed to the fine effective grains and ferrite/martensite microstructure facilitating a ductile fracture. Full article

Pumice forms when a volcanic explosion ejects highly pressurized, superheated rock, rapidly cooling and depressurizing, resulting in a porous structure. In countries with high volcanic activity, pumice stone is a low-cost natural material that is lightweight, non-toxic, eco-friendly, durable, and heat-resistant. Among other applications, pumice has been used as an aggregate to produce lightweight concrete or cementitious material to produce blended cement or geopolymer. Since pumice stone is highly porous, it could be used as a naturally occurring multiscale porous sound-absorbing material, which may add interesting properties for absorbing sound energy. Normally, a double-porosity granular material presents higher sound absorption at low frequencies than a solid-grain material with the same mesoscopic characteristics at a reduced weight. This study uses theoretical and experimental approaches to investigate the sound absorption characteristics of granular pumice samples. The tests were conducted on crushed pumice stones in granular form. The study suggests that pumice stones can be used as a novel material for sound absorption in room acoustics and noise control applications. Full article

Non-degradable plastic bags are a major contributor to marine and soil pollution. They represent a significant percentage of the generated solid waste and can last for hundreds of years in the environment. The aim of the present study was to find alternatives to conventional non-degradable plastic bags by obtaining biodegradable and compostable bags starting from simple materials like starch, poly(lactic acid) (PLA), and glycerol. Increasing the strength and hardness of the polymer was achieved by adding a mineral (talcum). The preliminary studies indicated that two compositions are suitable for advanced testing to produce the initial granular material. These materials were tested for the determination of melt flow index (MFI), Fourier Transform Infrared Spectroscopy (FTIR), and the polymers response to heating (thermogravimetric analysis, TGA and differential scanning calorimetry, DSC). The polymer biodegradability was evaluated by burial in two types of soil. The obtained results were compared with the same set of experiments performed on conventional polyethylene bags. After three months in the soil, only the materials synthesized in this study show signs of accentuated degradation while polyethylene bags are still intact. The surface morphology was explored by scanning electron microscopy (SEM). The results indicated that the biodegradable thermoplastic material meets the requirements of the European standard EN13432/2002 regarding compostable and biodegradable packaging. Full article