Search Results (6,431)

Wine lees, the residue left behind after racking or bottling of wine, are predominantly composed of dead yeast cells, ethanol, phenolic compounds, and tartrates. Yeast extract (i.e., commercial yeast extract), a highly nutritious powder derived from commercially cultivated yeast biomass, is commonly used in nutrient media as a nitrogen source. In the context of by-product valorization, wine lees could potentially be used to produce a substitute for commercial yeast extract (CYE). In our study we investigated the growth and fermentative ability of two major winemaking microorganisms, Lactiplantibacillus plantarum and Saccharomyces cerevisiae, in culture media containing a wine lees yeast extract (WLYE) and a CYE. The effects of yeast extract type, concentration, and initial cell concentration (y₀) on key kinetic parameters—maximum specific growth rate (μ_max), lag phase duration (λ), and maximum cell concentration (y_max)—were evaluated. For L. plantarum, the results showed that using a WLYE led to similar kinetic parameters to those obtained with a CYE, with λ being unaffected by y₀ in samples containing a WLYE. For S. cerevisiae, simultaneous addition of both yeast extracts led to increased μ_max values (up to 0.136 h⁻¹) compared to individually added yeast extracts, although this negatively affected λ and y_max. Current research on wine lees is mainly focused on using them as a substrate to produce valuable metabolites through fermentation, overlooking the potential industrial applications of the nutrient-rich autolysate. The findings of this study appear promising for the holistic valorization of wine lees, contributing towards the concepts of sustainability and circular economy. Full article

Spent carbon cathode (SCC) is one of the major hazardous solid wastes generated during the overhaul of electrolysis cells in the aluminum production process. SCC is not only rich in carbon resources but also contains soluble fluoride and cyanide, which gives it both recycling value and significant leaching toxicity. In this study, we explore the properties, emissions, and disposal strategies for SCC. Pyrometallurgy involves processes such as vacuum distillation, molten salt roasting, and high-temperature roasting. Hydrometallurgy describes various methods used to separate valuable components from leachate and prepare products. Collaborative disposal plays a positive role in treating SCC alongside other solid wastes. High-value utilization provides an approach to make full use of high-purity carbon-based materials. Finally, we analyze and summarize future prospects for the disposal of SCC. This study aims to contribute to the large-scale treatment and resource utilization of SCC while promoting circular economy principles and green development initiatives. Full article

Polyurethane foam (PUF) pads are widely used in semiconductor manufacturing, particularly for chemical mechanical polishing (CMP). This study prepares PUF composites with microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) to improve CMP performance. MCC and NCC were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), showing average diameters of 129.7 ± 30.9 nm for MCC and 22.2 ± 6.7 nm for NCC, both with high crystallinity (ca. 89%). Prior to preparing composites, the study on the influence of the postbaked step on the PUF was monitored through Fourier-transform infrared spectroscopy (FTIR). After that, PUF was incorporated with MCC/NCC to afford two catalogs of polyurethane foam composites (i.e., PUFC-M and PUFC-N). These PUFCs were examined for their thermal and surface properties using a differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), dynamic mechanical analyzer (DMA), and water contact angle (WCA) measurements. T_gs showed only slight changes but a notable increase in the 10% weight loss temperature (T_d10%) for PUFCs, rising from 277 °C for PUF to about 298 °C for PUFCs. The value of Tan δ dropped by up to 11%, indicating improved elasticity. Afterward, tensile and abrasion tests were conducted, and we acquired significant enhancements in the abrasion performance (e.g., from 1.04 mm/h for the PUF to 0.76 mm/h for a PUFC-N) of the PUFCs. Eventually, we prepared high-performance PUFCs and demonstrated their capability toward the practical CMP process. Full article

The investigation into the implementation and widespread adoption of oyster shell recycling methods aimed at restoring coastal ecosystems and enhancing water quality is currently limited. In this study, we investigated the utilization of oyster shell powder (OSP) as a cost-effective and environmentally sustainable method for treating high-fluoride-concentration wastewater, a byproduct of industrial processes. We conducted extensive laboratory testing to determine the optimal conditions for fluoride removal. This involved variations in OSP doses, particle sizes, and initial wastewater pH levels. The results of these tests showed that OSP achieved fluoride removal efficiencies exceeding 98% at an optimal dosage of 5 g/L. In addition, OSP effectively adjusted the wastewater pH from highly acidic (pH 2) to almost neutral (pH 6.87), demonstrating its effectiveness in real-world industrial wastewater treatment. OSP, derived from oyster shell waste, is rich in calcium carbonate and offers a novel approach to wastewater management by leveraging a natural waste product. This study demonstrates the potential of OSP as a waste management strategy and contributor to the circular economy by repurposing industrial byproducts. Full article

Currently, scientific studies have are focusing on environmentally friendly solutions, such as the effective use of waste in new green polymeric materials according to circular economy. Waste valorization is the main driving force for upcoming academic research. In this study, the impact of mussel particle size on reinforced biopoly(terphtalate ethylene) (bPET) is investigated. The waste filler was modified using NaOH. The filler content was 10 wt% and the same for all samples. The strength properties of the materials were determined in static tensile, bending and impact tests. The wetting angle was also analyzed for the obtained biocomposites. A low-cycle dynamic test was carried out to determine changes in dissipation energy and to observe the development of relaxation processes. This present study proves that preparation of new biocomposites based on waste mussels is an effective option in waste management. Full article

Bacterial cellulose (BC) has emerged as a sustainable biomaterial with diverse industrial applications. This paper examines BC production through a circular economy framework, focusing on organic waste as a primary feedstock. It compares static and agitated cultivation methods for BC production, highlighting their advantages and limitations. Static cultivation using Gluconacetobacter xylinum yields high-quality cellulose films but is constrained by lower yields and longer incubation times. Agitated cultivation accelerates production but may affect fiber uniformity. This paper emphasizes sustainability by exploring organic waste materials such as coffee grounds, tea leaves, and food scraps as cost-effective nitrogen and carbon sources. These materials not only lower production costs but also support circular economy principles by converting waste into valuable products. BC produced from these waste sources retains key properties, making it suitable for applications in the textile and other industries. In addition, BC production can align with vegan principles, provided that all additives and processing methods are free of animal-derived components. The paper discusses BC’s potential to replace synthetic fibers in textiles and reduce environmental impact. Case studies show successful BC integration into textile products. In conclusion, this paper calls for more research to optimize BC production processes and explore new industrial applications. Using organic waste in BC production can help industries adopt sustainable practices, reduce environmental footprints, and create high-value materials. Full article

Typical household recyclable bin in Australia contains around 60% of waste cardboard. Given the possibilities of developing a construction material, this study conducted a life cycle assessment (LCA) comparing the development of cardboard trusses with © timber trusses, encompassing production to construction. The results show that cardboard trusses offer significant environmental benefits, including a 73% reduction in climate change category, an 83% decrease in ozone-depleting potential, and almost complete avoidance of agricultural land occupation compared to timber trusses, showcasing their sustainability. In both material manufacturing and material transportation, cardboard trusses prioritize climate change mitigation, accounting for over half of the environmental impact. Timber trusses, in contrast, heavily impact land occupation and exhibit climate change dominance. A benefit analysis highlights advantages of cardboard trusses, particularly in reducing land occupation, sustainability, circular economy, and particulate matter formation. The life cycle cost analysis demonstrates an impressive 83% cost reduction for cardboard trusses compared to timber trusses, despite higher labor costs during manufacturing. Full article

This research tackled the food waste problem in Saudi Arabia, with a particular focus on family restaurants, where this issue is evident. The study adopted a semi-structured survey, including structured and open-ended questions with family restaurants’ owner–manager/managers. The results of quantitative and qualitative data analysis showed that the most frequent types of food waste in family restaurants are starchy foods, especially bread and rice with a waste ratio above 50% of these items. Additionally, the average ratio of food waste was at least 20% of served food at sampled restaurants per customer. Three major reasons for this high rate of food waste were consumers’ behavior, e.g., positive attitude towards food waste; external factors, e.g., absence of a legal framework; and factors related to restaurants, e.g., food portion served and food cycle management. The results identified no applied strategies for handling food left over and reducing food waste at most (70%) of Saudi restaurants. This study calls for a national policy and program on managing food waste at Saudi family restaurants by adopting the 5Rs model for proper food waste management. Restaurants are encouraged to adopt green initiatives, such as “clean your plate” or “eat or waste” to stimulate their customers’ behavior for reducing their food waste and sustain the environment. This would support a green and circular economy. Full article

Real-world energy efficiency in the building sector is currently inadequate due to significant discrepancies between predicted and actual building energy performance. As operational energy is optimized through improved building envelopes, embodied energy typically increases, further exacerbating the problem. This gap underscores the critical need to re-evaluate current practices and materials used in energy-efficient building construction. It is well established that adopting a life cycle view of energy efficiency is essential to mitigate the building sector’s contribution to rising global energy consumption and CO₂ emissions. Therefore, this study aims to examine existing research on sustainable building materials for life cycle energy efficiency. Specifically, it reviews recent research to identify key trends, challenges, and suggestions from tested novel materials. A combination of theoretical analysis and narrative synthesis is employed in a four-stage framework discussing the challenges, context, concepts, and the reviewed literature. Key trends include the growing adoption of sustainable materials, such as bio-fabricated and 3D printed materials, which offer improved insulation, thermal regulation, and energy management capabilities. Multifunctional materials with self-healing properties are also emerging as promising solutions for reducing energy loss and enhancing building durability. The focus on reusing materials from the agricultural, food production, and paper manufacturing industries in building construction highlights the opportunity to facilitate a circular economy. However, the challenges are substantial, with more research required to ascertain long-term performance, show opportunities to scale the implementation of these novel materials, and drive market acceptance. Full article

BIM is being strongly implemented in design companies. General contractors are using it during investment projects, and boards are using it for the maintenance and operation of buildings or infrastructure. Without the so-called BIM mandate (mandatory in public procurement), this is hard to imagine, even though it has already been implemented in many countries. In Poland, work in this direction is still being carried out. Due to the high complexity of investment and construction processes, the multiplicity of stakeholder groups, and conflicting interests, work on BIM adoption at the national level is hampered. The paper conducts an in-depth literature review of BIM implementation in Poland and presents a critical analysis of the current state of work. As a result of the literature research, proposals for changes in the processes of implementing the BIM mandate in Poland were formulated. This paper presents an excerpt from a potential BIM strategy and the necessary steps on the road to making BIM use mandatory. The results of the study indicate strong grassroots activity conducted by NGOs, which, independent of government actions, lead to measurable results. The authors propose that these activities must be coordinated by a single leading entity at the government level. The study could influence decisions made in other countries in the region or with similar levels of BIM adoption. BIM is the basis of the idea of the digital twin, and its implementation is necessary to achieve the goals of the doctrine of sustainable development and circular economy. Full article

This study examines the role of agritourism in developing strategies to promote a circular economy by applying the 3Rs (reduce, reuse, and recycle) and improving guests’ satisfaction. It contributes to filling the gap in the literature regarding the challenges posed, impact evidence, potential trade-offs, and socioeconomic considerations for the application of the 3Rs strategy in small tourism businesses. Interviews with hotel owners/hosts and guests were conducted through mainly qualitative methods, and the content was analyzed. This study reports on a case study conducted with a convenience sample of customers from a rural tourism company in Portugal to assess their position concerning the company’s 3Rs strategy. The case study reveals that common categories—hosts, breakfast, decoration, environment, and comfort—appreciated by guests align with the 3Rs practices. It was found that being environmentally responsible, taking part in the circular economy, and interacting with it can improve not only the satisfaction of guests but also hosts, thus creating memorable experiences for both. This study also shows that the position of customers regarding the 3Rs is not monolithic, with reusing and recycling emerging most prominently. This study shows that, in this context, a circular economy is feasible, provides tangible benefits, and successfully combines operational efficiency and guest convenience. This study also shows that it is possible to establish a successful tourism supply strategy based on a circular economy, particularly the 3Rs. Still, this strategy should not look at the 3Rs as if they were a uniform reality. Full article

The circular economy transition encompasses the identification of various available and sustainable materials to replace traditional binders in the construction industry. The utilization of water sediments represents this point as a beneficial action that may provide synergy in terms of waste reduction and replacement of energy-intensive materials. To explore the potential of water sediments, this study contemplated the characterization of water sediments as precursors for the design of alkali-activated materials (AAMs). The experimental approach was based on the detailed characterization of raw materials’ chemical, mineralogical, and basic material properties and the assessment of the designed AAM paste and mortar samples. The results achieved revealed the capability of low amorphous water sediments to form dense structures with favorable mechanical performance, reaching up to 36.8 MPa in compressive strength. The microstructural and water sorption characteristics point to the applicability of such materials in the building practice and, thus, the valorization of water sediments into valuable material. Full article

This study investigates the factors influencing ${CO}_2$ emissions in Romania from 1990 to 2023 using the Autoregressive Distributed Lag (ARDL) model. Before the ARDL model, we identified a set of six policies that were ranked using Fuzzy Electre, Topsis, DEMATEL, and Vikor. The multi-criteria decision-making (MCDM) methods have highlighted the importance of a circular policy on ${CO}_2$ emission reduction, which should be a central focus for policymakers. The results of the ARDL model indicate that, in the long term, renewable energy production reduces ${CO}_2$ emissions, showing a negative relationship. Conversely, an increase in patent applications and urbanization contributes to higher ${CO}_2$ emissions, reflecting a positive impact. In total, five key factors were analyzed: ${CO}_2$ emissions per capita, patent applications, gross domestic product, share of energy production from renewables, and urbanization. Notably, GDP does not significantly explain ${CO}_2$ emissions in the long run, suggesting that economic growth alone is not a direct driver of ${CO}_2$ emission levels in Romania. This decoupling might result from improvements in energy efficiency, shifts towards less carbon-intensive industries, and the increased adoption of renewable energy sources. Romania has implemented effective environmental regulations and policies that mitigate the impact of economic growth on ${CO}_2$ emissions. Full article

This research concerns the development and implementation of ground-breaking strategies for improving the sorting, separation, and recycling of common flexible laminate packaging materials. Such packaging laminates incorporate different functional materials in order to achieve the desired mechanical performance and barrier properties. Common components include poly(ethylene) (PE), poly(propylene) (PP), and poly(ethylene terephthalate) (PET), as well as valuable barrier materials such as poly(vinyl alcohol) (PVOH) and aluminium (Al) foils. Although widely used for the protection and preservation of food produce, such packaging materials present significant challenges for established recycling infrastructure and, therefore, to our future ambitions for a circular economy. Experience from the field of ionic liquids (ILs) and deep eutectic solvents (DESs) has been leveraged to develop novel green solvent systems that delaminate multilayer packaging materials to facilitate the separation and recovery of high-purity commodity plastics and aluminium. This research focuses on the development of a hydrophobic DES and the application of a Design of Experiments (DoE) methodology to investigate the effects of process parameters on the delamination of PE/Al/PET laminate packaging films. Key variables including temperature, time, loading, flake size, and perforations were assessed at laboratory scale using a 1 L filter reactor vessel. The results demonstrate that efficient separation of PE, Al, and PET can be achieved with high yields for material and solvent recovery. Recovered plastic films were subsequently characterised via Fourier-transform infra-red (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to qualify the quality of plastics for reuse. Full article

In light of mounting environmental concerns surrounding the overuse and accumulation of plastic waste, the United Nations (UN) has turned its attention towards sustainable materials and the Circular Economy (CE). Polymer recycling technologies have the potential to reduce the environmental impact and carbon footprint of plastic waste production, thereby contributing to the achievement of several Sustainable Development Goals (SDGs). In response to this challenge, students enrolled in the fourth year of secondary education, specializing in technology, during the 2021–2022 academic year, developed an open-source prototype that automatically transforms polyethylene terephthalate (PET) bottles into recycled rPET filament for 3D printing using an automated pultrusion model. In this working group, one of the students identified as gifted developed the pultrusion prototype using challenge-based learning and the project method (PM), which is now known as project-based learning. The resulting prototype has the capacity to transform PET bottles into rPET filament with mechanical properties comparable to those of commercial filaments, thereby enabling the manufacture of a wide range of products through 3D printing. It is not the intention of this work to create a commercial product. Rather, it is designed to promote social and sustainable entrepreneurship, CE, and the values of Education for Sustainable Development (ESD) through the recycling of polymers by means of 3D printing production. In addition, it seeks to develop the key competences for sustainability described in the methodological framework established by UNESCO in 2017. Full article