This study aimed to determine the environmental and health risks of the heavy metal levels in the Danube River in Hungary. The metals, including Fe, Mn, Zn, Cu, Ni, Cr, Pb, and As, were measured in the period from 2013 to 2019. The Spearman correlation and heatmap cluster analysis were utilized to determine the origin of pollution and the factors that control surface water quality. Several indices, such as the heavy metal pollution index (HPI), metal index (MI), hazard quotient oral and dermal (HQ), hazard index oral and dermal (HI), and carcinogenic risk (CR), were conducted to evaluate the potential risks for the environment and human health. The values of the HPI were between the range of 15 < HPI < 30, which indicated moderate pollution; however, the MI results showed high pollution in Dunaföldvár and Hercegszántó cities. The ecological risk (RI < 30) and HI values (< 1) showed low environmental risks and non-carcinogenic impacts of the existing metals, either on adults or children. The mean CR value of oral arsenic was 2.2E−04 and 2.5E−04 during April–September and October–March, respectively, indicating that children were the most vulnerable to arsenic-carcinogenic oral effects. While lead’s CR oral values for children during April–September exceeded the threshold of 1.0E−04, chromium’s oral and dermal CR values for both adults and children were 2.08E−04, 6.11E−04, 1.97E−04, and 5.82E−04 during April–September and October–March, respectively. These results demonstrate the potential carcinogenic risks related to chromium exposure within the two pathways in Hungary and highlight the need for effective measures to mitigate these risks.

Evaluation of water quality is crucial for managing surface water effectively, ensuring its suitability for human use, and sustaining the environment. In the lower Danube River basin, various methods were employed to assess surface water quality for irrigation, drinking, human health risk purposes and the main mechanism control the surface water chemistry. These methods included water quality indicators (WQIs), complex statistical analyses, geographic information systems (GIS), Monte Carlo simulation, and geochemical modeling. Physicochemical analyses of surface water samples revealed primarily Ca–Mg–HCO₃⁻ is the dominant water types. Principal component analysis (PCA), ionic ratios and piper, chloro alkaline index, Chadha, and Gibbs diagrams identified three distinct water characteristics influenced by water-rocks interaction, evaporation, ions exchange, and human activities. The geochemical modeling showed Danube River water’s strong ability to dissolve gypsum, halite, and anhydrite (SI < 0) and precipitate aragonite, dolomite, and calcite with saturation index (SI) value greater than 0 along its flow path. The irrigation water quality index (IWQI = 99.6–107.6), sodium adsorption ratio (SAR = 0.37–0.68), sodium percentage (Na% = 13.7–18.7), soluble sodium percentage (SSP = 12.5–17.5), Potential Salinity (PS = 0.73–1.6), and Residual Sodium Carbonate (RSC = − 1.27–0.58) values were used, mainly indicating acceptable quality with some limitations. Danube River water was unsuitable for drinking based on WQI value (WQI = 81–104). Oral exposure of children to specific components showed a higher hazard index (HI > 1) compared to adults, indicating a 2.1 times higher overall non-carcinogenic risk hazard index. However, Monte Carlo simulation demonstrated negligible iron, manganese, and nitrate health hazards for both age groups. These findings are valuable for water quality management decisions, contributing to long-term resource sustainability.

Lake Nasser in Egypt contains significant tilapia fish quantities, yet consumption remains low due to its geographical isolation from marketing and consuming areas. Therefore, investigating efficient and economical Tilapia fish drying methods is essential. The current study developed and tested a solar dryer based on solar energy collection, using evacuated tubes at three Nile Tilapia slice (NTS) thicknesses of 4, 8, and 12 mm, and an air velocity of 0.5 m/s. The obtained result of the solar dryer with evacuated tubes (SDET) was compared with the other results of the oven liquid petroleum gas (OLPG) as an industrial drying method. The results obtained showed that the air temperature inside the drying room of the SDET ranged between 44 and 75 °C. The average initial moisture content (MC) was 74.83% (w.b.). For both systems, the drying time ranged between 13 and 17 h at the same slice thickness. The effective moisture diffusivity was in the range of 0.87 × 10^–11 to 5.66 × 10^–11 m²/s. Furthermore, the mathematical modeling revealed the Modified Midilli (II) and Modified Henderson and Pabis models as the most suitable models to describe the drying behavior of NTS dried on SDET. On the other hand, the environmental analysis indicates that the developed SDET can mitigate approximately 273.6 tons of CO₂ during its lifetime, resulting in a carbon credit equivalent of approximately 19,838.89 $. Additionally, the economic analysis of the SDET showed that the annual production of dried fish was 450 kg; this may result in substantial cost savings, amounting to a total of 608.4 $ per year. Also, the developed SDET had a payback period of approximately 0.413 years or less than half a year.

With the widespread use of the Material Extrusion method in the 3D printing industry, it has become important to determine the optimum printing parameters to improve the mechanical characteristics of Polylactic Acid material according to the place of use. It is important to choose the right press parameters according to the forces to which the material is subjected. In research, we examined the impacts of 3D printing parameters such as Layer Thickness, Infill Density, Raster Angle, Printing Speed, and Wall Thickness on mechanical tests covering tensile, compression, flexural, impact, hardness, and surface roughness. We employed Taguchi analysis to streamline the number of experiments and determine the optimal printing parameters to maximize mechanical performance. Five samples were determined for each experimental design measurement. According to the results of the research, Layer Thickness and Infill Density parameters were found to be very important parameters in mechanical tests according to the effect and contribution ratios. The effect ranking of the Infill Density parameter on tensile, compressive and impact strength was the best (1) and the contribution rate was the highest (55.21%, 80.86% and 63.61%). In flexural strength, the order of effect and contribution rate (25.66%) were found in the 2nd place. The effect of Layer Thickness parameter on impact, hardness and surface roughness tests was found to be significant (2,1 and 1). The effect values in tensile and compression tests were also found to be moderate (3). Considering the efficiency levels and contribution rates for the other parameters, the order of importance can be listed as Wall Thickness, Raster Angle and Printing Speed. With the help of this study, the importance levels of the parameters during the formation of parts under combined forces were determined and presented to the literature.

This study evaluates the performance of an evacuated tube indirect solar dryer (ETISD) for drying tilapia strips at three thicknesses (4, 8, and 12 mm) using computational fluid dynamics (CFD), energy-exergy analysis, and sustainability indicators. CFD simulations were employed to analyze airflow patterns, temperature distribution, and velocity profiles inside the drying room (DR) across five air velocities (0.02–0.06 m/s). The optimal air flow rate of 0.03 m³/s provided a uniform drying temperature of 74.82 °C, at solar noon. Simulations over two consecutive drying days (8 a.m.–5 p.m.) further assessed thermal and aerodynamic behavior, enhancing system optimization. Energy analysis revealed that the evacuated tube solar collector (ETSC) achieved a maximum input energy of 1311.8 W and useful energy of 682.5 W, with energy efficiencies of 44.5–51.2% (ETSC) and 16.18–21.57% (ETISD). Exergy efficiencies ranged from 8.51 to 21.99% (ETSC) and 29.23–84.76% (ETISD), highlighting thermodynamic performance. Sustainability indicators, including improvement potential (IP) (2.71–6.69 W), waste exergy ratio (WER) (1.15–1.36), and sustainability index (SI) (1.09–1.28), demonstrated the system’s environmental and operational viability. These findings underscore the ETISD’s effectiveness for sustainable tilapia drying, balancing energy efficiency, thermal performance, and ecological impact.

This study presents an indirect mixed-mode solar dryer (IMMSD) integrated with a photovoltaic system with an automatic, temperature-responsive control system that automatically switches between natural and forced convection, enhancing efficiency and reducing energy use. Unlike previous fixed systems, it prevents over-drying and spoilage. The cost-effective, solar-powered design suits off-grid communities. By integrating drying kinetics with economic and environmental assessments, the system supports sustainability goals. The study also examines how slice thicknesses and tray positions within the drying room affect orange drying kinetics. Then, the IMMSD was used to dry orange slices under real conditions at Aswan University, Egypt, in January 2025, aiming to evaluate performance across different slice thicknesses (4, 6, and 8 mm) and tray positions (lower, middle, and upper levels). The results demonstrated that orange slices with a 4 mm thickness dried on the lower tray reached the final moisture content (MC) more quickly than thicker slices (8 mm) dried on the middle and upper trays. The 4 mm slices achieved the lowest final MC at approximately 12.5%, with a 48% reduction in drying time compared to 8 mm slices on the upper tray. The effective moisture diffusivity (D _eff ) ranged from 4.5 × 10⁻⁸ to 15 × 10⁻⁸ m²/s. Additionally, five semi-theoretical models—Midilli, Modified Midilli I and II, Aghbashlo, and Henderson–Pabis—provided the best fit for modeling the drying behavior of orange slices. The environmental analysis showed that the energy required for moisture evaporation ( $$\:{E}_{at}$$ ) increased with slice thickness, reaching 916.56, 1372.31, and 1839.76 kWh for 4, 6, and 8 mm slices, respectively. The 8 mm slices yielded the highest annual dried product output, net CO₂ reduction (90.72 tons), and the shortest energy payback time (0.85 years). Carbon credits ranged from 2179.29 to 4535.76 USD. Economically, the IMMSD required a low capital cost of 700 USD and annual costs of 996.12 USD, generating yearly savings of up to 14,015.9 USD, that reduced the payback period of investigation up to only about one month.