In Mexico, the mezcal industry consumes significant volumes of biomass as thermal energy and generates large amounts of organic waste. In each artisanal production batch, up to 246 m³ of firewood is burned, resulting in considerable CO₂ emissions and deforestation pressure. Simultaneously, approximately 2.4 tons of lignocellulosic bagasse are produced per 6 tons of fermented agave. This byproduct offers a calorific value (≈16.4 MJ/kg), making it a viable alternative as a solid biofuel. This study presents a discrete-event simulation model in Arena™, applied to an artisanal mezcal distillery in Tecamachalco, Mexico, to evaluate the technical feasibility of replacing part of the firewood with processed agave bagasse. The modeled process includes bagasse conditioning, indirect solar drying, grinding, briquetting, final drying, and combustion during distillation. The model incorporates cycle times, machine capacities, human resource availability, and process variability. Key performance indicators such as briquette yield, resource utilization and bottlenecks were analyzed. Sensitivity analysis under varying drying capacities, labor shifts, and demand scenarios identified solar drying as the critical constraint. Improvement strategies such as expanding dryer capacity and adopting hybrid systems were proposed to enhance throughput and energy substitution. The simulation demonstrates the potential to reduce firewood use by up to 30%, lowering environmental impact while valorizing agro-industrial residues. This approach contributes to more sustainable mezcal production, aligned with the principles of circular bioeconomy and rural energy transition.

Recycling of process water recovered from tailings dewatering unit operations in mineral processing has become a topical issue owing to the chemistry of recycled water being different from fresh water and how this difference may affect grinding chemistry in the mill, flotation chemistry, and the potential impact on flotation performance. This study examines the impact of recycled water addition to the mill on the flotation performance of a low-grade Cu-Ni-PGM ore over three successive cycles. Synthetic plant water of known ionic strength and composition was used as the baseline. Results showed that while water recovery and froth stability increased with recirculated water, the relationship with solids recovery was not linear suggesting reduced entrainment and a decoupling of froth stability from mineral recovery. Moreover, Cu recoveries showed slight improvement with recycling, while Ni recoveries showed a slight decrease. Significant variation in the accumulation of Ca²⁺, Mg²⁺, Cl⁻, and SO₄²⁻ was observed between recirculation strategies, affecting the electrical conductivity. The findings of this study highlight the importance of understanding water chemistry changes within closed-loop systems and its intersection with grinding and flotation processes. Insights from this study can inform water management strategies and reagent schemes that support both metallurgical performance and environmental compliance in PGM concentrators.

The tilt angle of photovoltaic (PV) panels is a critical factor in maximizing energy yield and reducing power generation costs, particularly across diverse climate zones. This study presents an enhanced optimization approach for monthly tilt angle adjustments, integrating anisotropic solar radiation modeling with ambient temperature effects. Six geographically distinct locations were analyzed to determine the optimal monthly and annual tilt angles, which varied significantly—from as low as 1° to over 58°—based on latitude and seasonal conditions. Simulation results demonstrate that monthly tilt optimization increases the annual energy output by 8.8–9.9% compared to that under a fixed annual tilt configuration. Accounting for ambient temperature further improves energy gains and reduces the overall cost of power generation. The results emphasize that while monthly adjustments offer the greatest benefits, seasonal or biannual adjustments still capture a substantial portion of the performance improvement. In this research, the PV system's annual and monthly energy generation, as well as system losses, is also analyzed and discussed to provide a comprehensive performance evaluation. This study underscores the importance of climate-specific PV panel orientation strategies to optimize efficiency and cost effectiveness. The proposed methodology serves as a practical framework for both system designers and policymakers aiming to improve the performance of solar installations under varying environmental conditions. It supports smarter deployment of solar technologies, contributing to more resilient and economically sustainable energy systems.

This study investigates the influence of particle grind size on metal dissolution, with a specific focus on improving gold recovery from pyrite-bearing low-grade cyanide tailings. Gold often exists as fine inclusions within pyrite, making it complex to recover using conventional methods. To address this challenge, both ultra-finely milled and unmilled pyrite concentrates were experimented in a leaching solution containing 3 kg/ton of sodium cyanide. The leaching process was conducted under controlled conditions, with pH maintained above 9.5 using unslaked lime and atmospheric oxygen present to enhance the reaction environment. A pulp density of 1.45 kg/L was used during the 24-hour leaching test. Samples were collected at intervals of 6, 9, 12, and 24 hours from a well-agitated leach drum, and the resulting solutions were analyzed to assess gold recovery. The experimental results demonstrated a clear relationship between finer grind size and improved gold dissolution. Notably, reducing the concentrate grind size from 32 µm to 25 µm led to a significant increase in gold extraction efficiency. Furthermore, a comparison between mill feed and mill product revealed a gold recovery increase from 47% to 62%, emphasizing the importance of ultra-fine grinding in unlocking encapsulated gold. This enhanced recovery is attributed to the improved liberation of gold particles, which allows for more effective interaction with the leaching solution. Consequently, these findings confirm that grind size is a key variable influencing the success of leaching processes for pyrite-hosted gold. This study highlights the value of particle size optimization in maximizing recovery from low-grade refractory cyanide tailings.

Passive Daytime Radiative Cooling (PDRC) represents a promising zero-energy strategy for thermal regulation by reflecting solar radiation while emitting heat through the atmospheric window (8–13 µm). In this study, PVDF-based PDRC coatings embedded with MgO and ZrO₂ nanoparticles were developed, characterized, and applied for sustainable cooling in agro-based systems. Nanocomposite coatings were prepared using polyvinylidene fluoride (PVDF) as the polymer matrix, incorporating MgO and ZrO₂ nanoparticles individually. Optical characterization showed that ZrO₂-PVDF achieved the highest solar reflectance of 0.96 with only 0.02 absorbance and 0.02 transmittance, while MgO-PVDF exhibited 0.94 reflectance, 0.02 absorbance, and 0.04 transmittance, indicating a high solar rejection and radiative cooling capability.

To evaluate practical cooling performance, coatings were applied on 5×5 cm metal and PET strips and exposed to ambient conditions. The MgO-PVDF-coated strip achieved surface temperatures as low as 28.7°C at 16:00 hours, compared to at 38.2°C ambient temperature and up to 52.9°C for black-coated controls. ZrO₂-PVDF also showed significant sub-ambient performance. For application-level validation, a transparent PET box was coated externally with the PDRC films. Under peak sunlight (10:00–16:00 hours), the coated PET box consistently maintained internal temperatures 8-11°C lower than the uncoated box, demonstrating the material’s effectiveness in real agro-climatic environments. This study establishes PVDF-based MgO/ZrO₂ nanocomposite coatings as scalable, passive, and power-free cooling solutions, suitable for post-harvest storage, packaging, and field-level applications in agriculture to reduce thermal stress and spoilage.

Due to the world's increasing demand for energy and high reliance on fossil fuels to produce it, there has been an urgent need to explore alternative ways to produce cleaner energy. Green diesel produced from renewable resources, such as waste vegetable oil, is a promising alternative due to its compatibility with petroleum diesel produced from fossil fuels. This study investigated the simulation of the hydrotreatment process of waste vegetable oil (WVO) to produce green diesel. ChemCAD version 8 was used to develop the simulation, and a kinetic model based on the Langmuir–Hinshelwood mechanism (an LH-C-ND model) was developed, where fatty acids such as oleic, stearic, and palmitic acid in WVO are converted into long-chain hydrocarbons (C15, C16, C17, and C18). The effect of the process parameters on the green diesel yield was assessed at different temperatures, pressures, and H2/oil ratios. The optimal conditions for green diesel production were identified as a temperature of 275°C and a pressure of 30 bar, with an H₂/oil ratio of 0.33. Optimisation efforts focused on minimising the formation of CO₂, CO, and water. In these operating conditions, a high green diesel yield was achieved, with the conversion of WVO exceeding 90%, and over 80% of the products were useful for green diesel. This study contributes to Sustainable Development Goal (SDG) 7, which aims to ensure access to affordable, reliable, sustainable, and modern energy for all by exploring the production of cleaner energy alternatives like green diesel from waste vegetable oil. It is recommended to recycle unreacted hydrogen to increase the efficiency and lower operational costs, as well as to conduct a life cycle assessment to evaluate the overall environmental impact.

The persistent challenge of removing fine particles from wastewater necessitates the development of environmentally sustainable and efficient treatment technologies. This study explores the application of micro-foam bubbles, also known as Colloidal Gas Aphrons (CGAs), made from plant-based surfactants on fine particle separation from wastewater. The performance of plant-based surfactants (Soapnut and Shikakai) was compared with that of a synthetic surfactant (Sodium Dodecyl Sulphate) in terms of flotation efficiency, foam stability, and water quality improvement. A series of experiments assessed the influence of the surfactant type, foam-to-feed ratio, solution pH, and column height on CGAs' performance. The results showed that SDS produced the highest average removal efficiency across all particle types (49.59%), followed by Soapnut (48.95%) and Shikakai (43.64%). However, Shikakai displayed superior removal performance for specific contaminants such as kaolinite and algae under certain conditions. The optimal foam-to-feed ratio was found to be 1.0 for SDS (60.59% removal), 0.5 for Shikakai (38.61%), and 0.1 for Soapnut (32.06%). Foam stability, a critical factor in flotation efficiency, varied significantly with the pH and surfactant type. Quantitative analysis revealed a strong negative correlation between foam stability and removal efficiency for Soapnut (r = -0.79) and Shikakai (r = -0.76), as well as a moderate positive correlation for SDS (r = 0.47). Additionally, the effect of column height on flotation efficiency confirmed that moderate sampling port heights (45–60 cm) provided optimal removal efficiencies due to enhanced contact time. This study demonstrates the potential of sustainable use of plant-based surfactants in CGA-based flotation and provides insights into optimising flotation parameters, thereby contributing towards greener water treatment processes.

This study investigates the effectiveness of phytoremediation for diesel-contaminated soil using rye grass and fescue grass in both controlled and natural conditions. The research examined plant performance across various soil compositions (100% topsoil, 50:50 soil-sand mixture, and 25:75 soil-sand mixture) with differing diesel oil concentrations (10, 15, and 20 ml/kg) and NPK fertiliser treatments (5, 10, and 15 g/kg). The experiment was carried out in two phases: an initial 7-day period under controlled laboratory conditions, followed by a 3-month period in natural outdoor conditions (July to October) to simulate real-world applications. During the outdoor phase, plants were exposed to typical Scottish weather, with average temperatures ranging from 17°C (July-August) to 13°C (October), and atmospheric pressure fluctuating between 980 and 1040 hPa. Initial experiments demonstrated that while both grass species exhibited resilience in contaminated environments, optimal growth occurred in 100% topsoil and 50:50 soil-sand mixtures, with minimal to no growth in 75% sand compositions. Oil concentration after phytoremediation was measured using UV spectrophotometry at a 306 nm wavelength and converted using the calibration curve equation Y = 0.5731 x (where Y is absorbance and x is oil concentration percentage), revealing varying effectiveness across soil compositions. Results indicated significantly lower remaining oil concentrations in 25% soil mixtures compared to 100% soil samples, primarily due to higher soil permeability in sand-mixed samples. For both grass types, the remaining oil concentration ranged from approximately 0.2% to 1.2% wt/wt across different initial contamination levels, with both rye and fescue grass demonstrating comparable remediation capabilities. The addition of NPK fertiliser showed promising results in enhancing plant growth and potential remediation capabilities. This research contributes to an understanding of the practical applications of phytoremediation, particularly focusing on the role of soil composition and nutrient supplementation in plant survival and diesel concentration reduction under both controlled and natural conditions.

Electroporators are widely used devices for educational and research purposes, particularly in molecular biology and genetic engineering, where they enable the introduction of foreign DNA into cells through the application of high-voltage electric pulses. Despite their utility, their high cost limits accessibility in educational and research institutions in developing countries, restricting hands-on training and the development of local biotechnological capacities. At the same time, the global increase in electronic waste has reached alarming levels, raising environmental and economic concerns. In this context, the aim of this study was to develop a functional electroporator prototype using components recovered from discarded electronic devices. The device was built using a flyback-based circuit that generated logarithmic decay pulses with a duration of 5.00 ± 0.25 ms. Pulse control was achieved through a simple resistor–capacitor (RC) circuit connected to the gate of a MOSFET, powered with 200 V at the input, and subsequently stepped up by a transformer. Stainless steel needle electrodes were used, with a separation of 1.00 ± 0.05 mm. Performance was evaluated following the protocol described by Sambrook et al. (2001), using Escherichia coli DH5α strains. Transformed cells were cultured in Luria–Bertani (LB) medium supplemented with ampicillin, yielding an average of one colony per 200 µL of culture. The results support the feasibility of building low-cost electroporators from recycled components, contributing to sustainable technology development.

Microreactors can serve as advanced treatment units for end-of-pipe solutions in drinking water purification. They provide high surface-area-to-volume ratios and precise control over the reaction conditions, enabling a superior mass and heat transfer performance compared to that of conventional reactors. In the context of advanced oxidation processes, miniaturized flow reactors enhance the degradation efficiency for persistent pollutants by promoting effective mass transport under laminar flow conditions. The reduced diffusion distance between the aqueous phase and the immobilized catalyst layer minimizes mass transfer limitations. This effectively sorts out one of the main challenges associated with heterogeneous photocatalysis. Equally, nitrosamines are hazardous disinfection byproducts formed during water treatment when nitrogenous precursors react with chlorine or chloramine. Particularly, N-nitrosodimethylamine (NDMA) is among the most frequently detected nitrosamines, with a World Health Organization (WHO) guideline value of 100 ng/L in drinking water due to its carcinogenic potential. In this study, the degradation efficiency of a tandem microreactor system was evaluated. The system comprised two continuous-flow microreactors operated in series: the first consisted of a UV-irradiated column packed with TiO₂ immobilized on a biopolymeric matrix, while the second contained an activated carbon-packed bed. An aqueous NDMA solution (1 ppm, pH 3, 20 °C) was introduced under plug-flow conditions, with the temperature and pressure regulated via a Peltier module and a pressure control unit. NDMA degradation was monitored using liquid chromatography–tandem mass spectrometry (LC-MS/MS), revealing a removal efficiency of 87.6%.