Search Results (51)

The galvanic industry requires considerable amounts of water and produces significant quantities of wastewater. Two types of wastewater are created in the processes of the galvanic application of metal coatings: used galvanic baths and wastewater generated while rinsing coated elements. The composition and amount of wastewater depend on the type of process, the plant’s operational system, and the quantity of water utilised to rinse the coated elements. In this article, the possibilities of using different techniques, such as chemical precipitation, coagulation and flocculation, ion exchange, adsorption, and membrane filtration, to remove heavy metals from galvanic wastewater were analysed and assessed. It was determined that the use of physicochemical methods (i.e., chemical precipitation, coagulation, and flocculation) to remove heavy metals has significant disadvantages, including operational costs connected with the purchase of chemical reagents and the emergence of metal complexes requiring management/utilisation. On the other hand, the processes of ion exchange and adsorption can be used only for wastewater characterised by a low heavy metal concentration, with organic matter preliminarily removed. In addition, waste polluted with heavy metals in the form of used regenerative baths and used sorbents is generated during these processes. In turn, the advanced techniques of membrane filtration allow for the removal of different types of organic pollutants and heavy metals. The processes of membrane wastewater treatment exhibit a range of advantages compared to traditional technologies, including the complete, environmentally friendly removal of permanent organic pollution, easy integration into conventional technologies, a limited amount of residue, a high level of separation, and a shorter process time. The efficiency of membrane wastewater treatment depends on many parameters, including, most of all, the composition, pH, and type of membrane, as well as process conditions. The possibility of using new types of membranes to remove heavy metals from spent galvanic baths was analysed, and the possibility of using the processes in wastewater treatment systems according to the circular economy model was assessed. The assessment of the efficiency of heavy metal removal in hybrid systems combining specific individual processes and the development of state-of-the-art material solutions to realise these processes may be an interesting direction of research in this field. Full article

Oil-in-water emulsions (O/W emulsions) are generally used to lubricate the cold rolling process of low-carbon steel. In addition to the obvious advantages of efficient lubrication and cooling of the process, there are also some disadvantages, mainly related to emulsion bath maintenance, subsequent production steps and waste disposal. In some application areas, Oil-Free Lubricants (OFL’s) have been shown to be at least equally effective in decreasing friction and wear as conventional oil-based lubricants, while resulting in benefits related to waste disposal. In 2023, a project named “Transfer of aqueous oil free lubricants into steel cold rolling practice” (acronym ‘RollOilFreeII’) began, with it receiving funding from the Research Fund for Coal and Steel (RFCS). This project aims at an industrial application of Oil-Free Lubricants in the steel cold rolling process. The project builds on the work of the ‘RollOilFree’ project (also carried out in the RFCS-framework). This article briefly recapitulates the findings in the RollOilFree project and describes the objectives, benefits, activities and first results of the RollOilFreeII project. Notably, a pilot mill trial at high speed has been carried out, showing a good performance of the investigated OFLs. Back-calculated friction values were equal to, or even slightly lower than, reference O/W emulsions. The strip cleanliness with OFLs is much better than it is with the reference O/W emulsions. Only for a very thin product, as is the case in tinplate rolling, does the direct application of a conventional O/W dispersion (a high-particle-sized O/W emulsion) give a better performance than the investigated OFLs. Further development of OFLs should focus on this aspect. Full article

Coastal bathing waters are leading tourist destinations, mainly during holiday periods. Therefore, the quality of bathing waters is of key importance to tourists. In 2006, the European Union (EU) adopted the Bathing Water Directive (BWD). EU Member States are required to analyze the status of their bathing waters, the quality of which is determined by the presence or absence of microbial contaminants (Escherichia coli and enterococci). This study presents the quality of coastal bathing waters in Portugal and Poland during the 3-year period from 2020 to 2022. The difference in the bathing water quality of the two countries—excellent in Portugal versus worse in Poland—is caused by their contrasting management and sampling practices and differing geographical and environmental conditions (in Portugal, warm, open sea, and in Poland, a temperate, semi-enclosed sea that is almost surrounded by land and is exposed to urban wastewater discharge). Additionally, the results of a questionnaire showed that ecological awareness and responses are well developed in Portuguese and Polish students regardless of the different status of their bathing waters. To the best of the authors’ knowledge, this study is among the first to analyze the relationships between water pollution and students’ ecological awareness and opinions on tourism. The results provide valuable information that policymakers, tourist entities, and educational institutions can use to develop more efficient management strategies for the coastal bathing waters in both countries. Full article

PHPs (pulsating heat pipes) are widely used as an efficient heat transfer element in equipment thermal management and waste heat recovery due to their flexibility. The purpose of this study was to design a heat transfer device that utilizes an asymmetric pulsating heat pipe structure by adjusting the lengths of selected pipes within the entire circulation pipeline. In the experiment, a constant temperature water bath was used as the heat source, with heat dissipated in the condensing section via natural convection. An infrared thermal imager was used to record the temperature of the condensing section, and the local wall temperature distribution was measured in different channels of the condensing section. Based on an in-depth analysis of the wavelet frequency, the following research conclusions are drawn: Firstly, as the heat source temperature increases, the start-up time of the pulsating heat pipe is shortened, the operating state changes from start–stop–start to stable and continuous oscillation, and the oscillation mode changes from high amplitude and low frequency to low amplitude and high frequency. These changes are especially pronounced when the heat source temperature is 80 °C, which is when the thermal resistance reaches its lowest value of 0.0074 K/W, and the equivalent thermal conductivity reaches its highest value of 666.29 W/(m·K). Secondly, the flow and oscillation of the working fluid can be effectively promoted by appropriately shortening the length of the condensing section of the pulsating heat pipes or the heat transfer distance between the evaporation and condensing sections. Third, under a low-temperature heat source, the oscillation frequency of each channel of a pulsating heat pipe is found to be low based on wavelet analysis. However, as the heat source temperature increases, the energy content of the temperature signal of the working fluid in each channel changes from a low- to a high-frequency value, gradually converging to the same characteristic frequency. At this point, the working fluid in the pipes no longer flows randomly in multiple directions but rather in a single direction. Finally, we determined that the maximum oscillation frequency of working fluid in a PHP is around 0.7 HZ when using the water bath heating method. Full article

Remote sensing for water quality evaluation has advanced, with more satellites providing longer data series. Validations of remote sensing-derived data for water quality characteristics, such as chlorophyll-a, Secchi depth, and turbidity, have often remained restricted to small numbers of water bodies and have included local calibration. Here, we present an evaluation of > 100 water bodies in Germany covering different sizes, maximum depths, and trophic states. Data from Sentinel-2 MSI and Sentinel-3 OLCI were analyzed by two processing chains. Our work focuses on analysis of the accuracy of remote sensing products by comparing them to a large in situ data set from governmental monitoring from 13 federal states in Germany and, hence, achieves a national scale assessment. We quantified the fit between the remote sensing data and in situ data among processing chains, satellite instruments, and our three target water quality variables. In general, overall regressions between in situ data and remote sensing data followed the 1:1 regression. Remote sensing may, thus, be regarded as a valuable tool for complementing in situ monitoring by useful information on higher spatial and temporal scales in order to support water management, e.g., for the European Water Framework Directive (WFD) and the Bathing Water Directive (BWD). Full article

This research proposes an efficient alternative for dehydrating cassava bagasse to address the inherent challenges in the handling, transportation, storage, and preservation of this agro–industrial residue generated in cassava starch production plants. This residue is characterized by high moisture retention, considerable volume, and hydrophilic nature, complicating conventional drying methods. This study evaluates the impact of emerging ultrasound (US) and pulsed electric field (PEF) technologies prior to convective drying to enhance the dehydration efficiency of cassava bagasse, aiming at its valorization and contributing to the sustainability of the cassava starch industry. The findings reveal that pretreatment with ultrasound (US) and pulsed electric fields (PEF) significantly reduces the drying time of cassava bagasse compared to convective drying alone. With probe ultrasound at 26 kHz for 30 min, the drying time is reduced by 72% (3.83 h vs. 14.0 h); with bath ultrasound at 37 kHz for 30 min, it is reduced by 56.0% (6.16 h vs. 14.0 h); and with PEF at 7.5 kV/cm for 30 min, it is reduced by 52.4% (6.66 h vs. 14.0 h). These emerging technologies increased the effective diffusivity and modified the molecular structure of the bagasse, thereby improving mass transfer and drying process efficiency. These results are particularly useful for developing more efficient and sustainable strategies for drying agricultural by-products, with direct implications for the post-industrial treatment of agro–industrial residues with high water content. Full article

High production rates and the constant expansion of production capacities for lithium-ion batteries will lead to large quantities of production waste in the future. The desired achievement of a circular economy presupposes that such rejects could be recovered. This paper presents a two-staged process route that allows one to recover graphite and conductive carbon black from already coated negative electrode foils in a water-based and function-preserving manner, and it makes it directly usable as a particle suspension for coating new negative electrodes. In a first step, coating residues, which accumulate in production (as offcuts or rejects for example), are decoated in an aqueous ultrasonic bath. The ultrasonic bath also serves as a pre-thickener. As a result, high mass concentrations of active material can already be achieved in the water after the first process step. Water is then removed from the negative electrode suspension in a subsequent step by applying dynamic cross-flow filtration. With this unit operation, it is possible to concentrate the slurry residue to a solid content similar to that of the new electrode slurries used for coatings. An important criterion for the direct utilization of production waste is that the particle properties are affected as little as possible so that the suspension can be used directly for coating new films. This work presents the individual recycling process steps and their influence on the particle and slurry properties. The aim is to assess whether the recyclate is suitable for a coating of new negative electrodes and thus also for manufacturing batteries from 100% recycled material. Full article

Bent wood has the advantages of visually appealing and ergonomic shapes and the disadvantage of processing failure. Understanding how water and temperature influence wood bending is critical to avoid processing failure. Compared with softwood, saturated hardwood has been seldom reported in terms of bending performance at various temperature levels. In this paper, white birch and ash wood were studied in bending using a universal testing machine and a program-controlled water bath. White birch wood exhibited lower proportional limit stress, smaller modulus of elasticity (MOE), and lower failure stress, but higher proportional strain and failure strain than ash wood. At 20 °C, bending of air-dried wood on the tangential direction exhibited much smaller mechanical variation than that on the radial direction. The proportional limit stress, MOE, and failure stress of water-saturated wood were much smaller than those of air-dried wood, while failure strain was much higher. Evidenced by the almost constant proportional limit strain, plastic bending deformation of water-saturated wood happened to a great extent. As the temperature elevated at 20–100 °C, MOE, proportional limit stress, and failure stress of water-saturated wood decreased while proportional limit strain, failure strain, and wood toughness increased. Variation in proportional limit strain resulting from temperature change was ignorable, evidencing that elevated temperature enhanced wood plastic deformation. Furthermore, white birch wood was more susceptible to temperature over 40 °C than ash wood in terms of toughness. Under water-saturated condition, both species exhibited excellent bending performance at relatively high temperature. Full article

In this study, graphene quantum dots (GQDs) have been incorporated into the g-C₃N₄/ZIF-67 heterojunction system as a photosensitizer to enhance photocatalytic conversion of CO₂-to-CO. The GQDs are deposited onto the surface of g-C₃N₄/ZIF-67 using a simple water bath procedure. As expected, GQDs/g-C₃N₄/ZIF-67 presents outstanding performance in CO₂ photoreduction. Among the GQDs/g-C₃N₄/ZIF-67 ternary photocatalysts, 7 GQDs-CN/ZIF-67 exhibits the best photocatalytic CO₂ reduction ability with a CO yield of 51.71 μmol g⁻¹, which is 5.05 and 1.87 times more than pristine g-C₃N₄ (10.24 μmol g⁻¹) and g-C₃N₄/ZIF-67 (27.65 μmol g⁻¹), respectively. This result shows that upon combination of GQDs with ZIF-67/g-C₃N₄, GQDs can be used as photosensitizers to improve the optical absorption capacity of the photocatalyst. Furthermore, GQDs serve as electron channels, facilitating the transport of photo-induced electrons from ZIF-67 to g-C₃N₄, which promotes photogenerated carrier separation efficiency. This study innovatively adds GQDs to the heterojunction and applies the prepared ternary composite to the CO₂ photoreduction, which inspires a novel direction for the design of non-noble metal photocatalysts. Full article

The pipeline direct drinking water system (PDDWS) has emerged to ensure the quality of direct drinking water. Nevertheless, the existing literature suggests that the PDDWS suffers from inherent structural technological deficiencies, and various internal and external factors hinder its reliability, which raise concerns about the scientific and rational basis of the PDDWS. To address these issues, a new-type terminal differentiated water system (TDWS) is proposed to establish an efficient and health-oriented household water supply system. A water purifier is directly installed at the user’s terminal, and, due to its diversion process, differentiated water is provided, including direct drinking water, clean water and flushing water. Direct drinking water can be produced on demand, without secondary contamination. Clean water is also not stored, thus preventing microbial growth and ensuring superior water quality compared to tap water, suitable for kitchen usage. Flushing water is mixed with tap water for laundry, bathing and toilet flushing. Engineering verification has demonstrated that the quality of the direct drinking water and the clean water exceeds national standards. With the diversion process, the TDWS exhibits benefits related to health, the economy, applicability and environmental friendliness, and it can serve as a supplement and innovation for the PDDWS. Full article

The objective of this study was to develop effervescent cleansing tablets that can be dissolved and turned into liquid soap, which can be used for bathing or soaking the body. The asiatic-acid-loaded solid lipid microparticles (AASLMs) were prepared via the hot emulsification method followed by cold re-solidification and then freeze-dried to obtained dry powder. The physicochemical properties such as morphology and % entrapment efficiency (%EE) were evaluated. The results revealed that AASLMs have an irregular shape, and the %EE for the resulting AASLMs was 92.04 ± 3.43%. The tablets were manufactured via the direct compression technique. The compatibility test was conducted to ensure that the excipients are compatible with the active ingredient. The angle of repose, Carr’s index, and Hausner’s ratio were studied to evaluate the flowability of the powder blend before compression. The weight of each tablet was set to 1000 mg, and physicochemical characteristics, in vitro dissolution, ex vivo cleansing efficacy, and stability were evaluated. The results showed that the active ingredient was compatible with other excipients, as the results obtained from FTIR spectra indicated the absence of potential chemical interaction between the active ingredient and excipients used in this study. Additionally, all formulations had good flow properties. The effervescence times of selected formulations, F2 and F3, were <5 min, with favorable pH and hardness values. The friability values of all formulations exceeded 1% because the excipients used in effervescent tablets are very fragile. The release of asiatic acid (AA) from the tablets was dependent on the concentration of SLS. In an ex vivo test, it was discovered that the developed products F2 and F3 showed much more effective cleansing efficacy than water. Nevertheless, brown spots appeared in the tablets and the AA content was significantly decreased in both tested formulations after 3 months’ storage at 40 ± 2 °C/75% RH ± 5% RH. The stability study revealed that the developed products were not stable at high temperature and humidity. Therefore, it is recommended that the developed effervescent tablets are not stored at a high temperature. Full article

In recent decades, the world’s population is progressively shifting towards coastal areas, and it is estimated that it could reach 1 billion by 2050. On the other hand, meteocean forcings show increasing modification in terms of the occurrence and frequency of energetic events related to climate change trends. Then, the definition of adaptation strategies is crucial to managing coastal areas, especially in the most densely populated or highly valued tourist and environmental areas. Meaningful long-term strategies should then be based on quantitative estimation of future scenarios in a changing climate. Although most of the studies in the literature focus on extreme events, this paper aims to assess, through synthetic indicators, whether and how average and mild energy conditions related to wave climate will vary considering the current situation compared to future projections. The study is based on the analysis of wave data. The projection of average and mild energy conditions can indeed influence, just for example, the long-term morphodynamics of sandy beaches and the quality of bathing waters. Data extracted from the Copernicus database are considered. The methodology has been applied to the case of Sardinia island at a regional scale. Then, the aim of this paper is twofold: on the one hand, a method is proposed to evaluate the variation of average and mild wave conditions; on the other hand, it aims to apply the method to the case study of the Sardinia coastal area to highlight its feasibility. Results confirm that variations are expected. In the analyzed case study, it emerges that, on average, the long-term evolution of the wave climate shows a tendency toward intensification, while a decrease in the frequency of calm conditions is estimated. The average annual number of events undergoes an increase. Moreover, changes in wave directional sectors are observed, which, from being unimodal, are estimated to exhibit bimodal characteristics in particular on the west coast of the island. Full article

As a representative service industry, the hotel industry has a complex water-use structure and high water consumption. It is of great significance to investigate the mechanisms determining hotel water-use behavior for demand analysis, as this would make it possible to enhance water-use efficiency and enact targeted water-saving measures. Using Spearman’s hierarchical correlation coefficient, the multi-layer perceptron (MLP) neural network model, and the structural equation model (SEM), in this study, we explored the mechanism determining hotel consumers’ water-use behavior from different dimensions and constructed a typical water-use behavior model based on the MLP-SEM model. In terms of individual water-use behavior, the results showed that individual characteristics, water-conservation awareness, and consumption behavior possessed significant differences regarding their influence on and correlation with various water-use behaviors. The most relevant factors influencing each behavior, namely washing up, hand washing, and drinking, were daily stay in the hotel, education, and income. Gender had the greatest impact on bathing and toilet-flushing water-use behaviors. The importance of daily stay in the hotel was 0.181, which meant that this was the most significant factor influencing the direct water-use behavior of hotel guests. The following factors were identified: hotel type, income, age, and gender. Typical individual characteristics had a significant impact on main water-use behaviors, whereas typical consumption behaviors had no effect. These results can provide a foundation for relevant research in other industries and serve as a basis for a prediction model of water consumption in hotels based on water-use behavior. Furthermore, they provide a basis for the delicate management of water-use behavior in hotels, making it possible to effectively guide the public to consciously adopt water-saving habits, thus improving water efficiency, which could alleviate the shortage of water resources in the long-term. Full article

Vibrios, such as Vibrio parahaemolyticus, are naturally occurring halophilic bacteria that are a major cause of foodborne illness. Because of their autochthonous nature, managing vibrio levels in marine and estuarine environments is impossible. Instead, it is crucial to reliably enumerate their abundance to minimize human exposure. One method of achieving this is the direct plating/colony hybridization (DP/CH) method, which has been used to efficiently quantify pathogenic vibrios in oysters and other seafood products. Although successful, the method relies on proprietary resources. We examined alternative approaches, assessed the influence of the reagent suppliers’ source on enumeration accuracy, and made experimental adjustments that maximized efficiency, sensitivity, and specificity. We report here that in-house conjugation via Cell Mosaic is a viable alternative to the previously available sole-source distributor of the alkaline phosphatase-conjugated probes used to enumerate vibrios in oysters. We also report that milk was a viable alternative as a blocking reagent, pH must be eight, an orbital shaker was a viable alternative to a water bath, and narrow polypropylene containers were a viable alternative to Whirl-Pak bags. These modifications will be crucial to scientists enumerating vibrios and other pathogens in food products. Full article

Bottom-blowing copper smelting is a bath smelting technology recently developed in China. It has the advantages of good adaptability of raw materials, high oxygen utilization and thermal efficiency, and flexible production capacity. Plume eye is a unique phenomenon observed in the bottom-blowing copper-smelting furnace where the slag on the surface of the bath is pushed away by the high-pressure gas injected from the bottom. The existence of plume eye was first confirmed by analyzing the quenched industrial samples collected above the gas injection area and then investigated by laboratory water model experiments. Combining the plant operating data and the smelting mechanism of the copper concentrate, the role of the plume eye in bottom-blowing-enhanced smelting is analyzed. It reveals that the direct dissolution of copper concentrate as a low-grade matte into the molten matte can significantly accelerate the reactions between the concentrate and oxygen. The productivity of the bottom-blowing furnace is therefore increased as a result. The effects of the gas flow rate and thickness of the matte and of the slag layer on the diameter of the plume eye were studied using water-model experiments. It was found that increasing the gas flow and the thickness of the matte and reducing the thickness of the slag can increase the diameter of the plume eye. This work is of great significance for further understanding the copper bottom-blowing smelting technology and optimizing industrial operations. Full article