Search Results (112)

Biodegradable polymer composites offer promising alternatives to petroleum-based plastics, supporting the principles of a zero waste and circular economy. This study investigates the reinforcing potential of alkali-treated wood flour derived from recycled pine (Pinus brutia Ten.) and poplar (Populus alba L.) waste wooden pallets in poly(lactic acid) (PLA) biocomposites. Wood flour was initially recovered through grinding and screening during recycling, followed by alkali treatment via a green chemistry approach to enhance interfacial bonding with the PLA matrix. The impact of alkali concentration and two fabrication methods—additive manufacturing (AM) and injection molding (IM)—on the properties of developed biocomposite materials was assessed through mechanical, physical, morphological, and thermal analyses. IM samples outperformed AM counterparts, with the IM PLA containing 30 wt% wood flour (alkali-treated with 10% solution) showing the highest mechanical gains: tensile (+71.35%), flexural (+64.74%), and hardness (+2.62%) compared to untreated samples. Moreover, the AM sample with 10 wt% wood flour and 10% alkali treatment showed a 49.37% decrease in water absorption compared to the untreated sample, indicating improved hydrophobicity. Scanning electron microscopy confirmed that alkali treatment reduced void content and enhanced morphological uniformity, while thermal properties remained consistent across fabrication methods. This work introduces a green composite using non-toxic materials and treatments, facilitating eco-friendly production aligned with zero waste and circular economy principles throughout the manufacturing lifecycle. Full article

Drug removal from urban wastewater (UW) is a topic of growing interest. The new European Directive addresses this problem by introducing quaternary treatment by 2045, as part of the “Zero Pollution” plan from a One Health perspective. In this context, the role of microalgae remains very promising in achieving clean and safe effluents, although its cost–benefit ratio needs to be carefully evaluated. The purpose of this review is to disclose the latest approaches to drug removal and energy recovery from UWs adopting different algae (Chlorella spp., Galdieria spp., and Scenedesmus spp.), to provide a detailed background for further research towards the development of new effective strategies on UW remediation while producing clean energy. We examined the most recent studies, considering most drugs found in wastewater, their management, as well as strategies used to recover energy while being mindful of a circular economy. There is growing interest in algae-based systems. The latest findings on algae–bacteria consortia show that it could be a better alternative to suspended biomass and represent a way to manage drug waste. This finding suggests that large-scale experiments should be conducted to confirm the potential benefits of such waste treatments. Full article

The increasing demand for sustainable energy and clean water has prompted the exploration of alternative solutions to reduce reliance on fossil fuels. In this context, hydrogen production through water electrolysis powered by solar energy presents a promising pathway toward a zero-carbon footprint. This study investigates the potential of copper slag, an abundant industrial waste, as a low-cost electrocatalyst for the hydrogen evolution reaction (HER) in contact with saline water such as 0.5 M NaCl and seawater, comparing the electrochemical response when in contact with geothermal water from El Tatio (Atacama Desert). The physicochemical characterisation of copper slag was performed using XRD, Raman, and SEM-EDS to determine its surface properties. Electrochemical evaluations were conducted in 0.5 M NaCl and natural seawater using polarisation techniques to assess the corrosion behaviour and catalytic efficiency of the copper slag electrodes. The results indicate that copper slag exhibits high stability and promising HER kinetics, particularly in seawater, where its mesoporous structure facilitates efficient charge transfer processes. The key novelty of this manuscript lies in the direct revalorisation of untreated copper slag as a functional electrode for HER in real seawater and geothermal water, avoiding the use of expensive noble metals and aligning with circular economy principles. This innovative combination of recycled material and natural saline electrolyte enhances both the technical and economic viability of electrolysis, while reducing environmental impact and promoting green hydrogen production in coastal regions with high solar potential. This research contributes to the value of industrial waste, offering a viable pathway for advancing sustainable hydrogen technologies in real-world environments. Full article

Road transport plays a significant role in the economic growth of a country. Conventional internal combustion engines (ICEs) are widely used in automobiles, with an efficiency range of 25% to 35%, while the remaining energy is lost through cooling and exhaust gases. Additionally, two parasitic loads—the alternator and the air conditioning (AC) compressor—are driven by the ICE via a belt, further reducing efficiency. In this paper, energy and exergy analysis of the waste heat of exhaust gases has been performed for automobiles equipped with ICEs, i.e., R06A, F8B, K10B, 2NZ-FE, and 2ZR-FE, to evaluate their potential to drive these parasitic loads. The working cycles of these ICE models were simulated using a zero-dimensional MATLAB model based on fundamental governing equations. The results indicate that approximately 10–40 kW of energy is lost through exhaust gases under varying operating conditions for the examined ICEs. The average exhaust gas temperature and mass flow rate for these ICEs are approximately 900 K and 0.016 kg/s, respectively. Based on these findings, an E-turbine retrofit system is proposed to operate under these conditions, recovering exhaust energy to power the alternator and AC compressor. The results showed that the E-turbine generated 6.8 kW of mechanical power, which was converted into 4 kW of electrical power by the generator. This electrical power was used to supply the parasitic loads, thereby enhancing the overall efficiency of ICE. Full article

Starch, as a natural, low-cost, and vegan-friendly raw material, aligns well with the growing demand for sustainable, zero-waste, and waterless cosmetic products. Its biodegradability and natural origin allow for minimal environmental impact during production and disposal. Anhydrous lotion body bars, solid and water-free alternatives to traditional moisturizers, offer high concentrations of active ingredients that are more effective and have a longer shelf life. Their solid form enables packaging in paper-based containers, reducing plastic waste. To address formulation challenges such as excessive greasiness, poor absorption, or lack of structural stability, which are often associated with the high oil content of anhydrous body lotion bars, starch may serve as a promising natural additive. The aim of this study was to optimize the formulation of an innovative starch-based anhydrous lotion bar. For this purpose, physicochemical analyses of starches from various botanical sources (corn, rice, tapioca, waxy corn and potato) were performed, along with evaluations of the functional (including commercially acceptable form, hardness sufficient for application, product stability, reduced greasiness and stickiness) and mechanical properties of the resulting bars. Additionally, the rheological behavior was described using the De Kee model. The results indicate that a 2.5% starch addition, regardless of its botanical origin, provides the best balance between viscosity and ease of application. Moreover, starches with a low moisture content and high oil absorption capacity effectively reduce the greasy skin sensation. These findings demonstrate the potential of starch as a natural multifunctional additive in the development of stable, user-friendly anhydrous lotion body bars. Full article

With the increase in greenwashing, corporate greenwashing governance has become a crucial component of urban environmental management. Industrial clusters are a key form of urban economic organization, yet the mechanisms through which they affect corporate greenwashing remain unclear. This study examines how different types of industrial agglomeration influence corporate greenwashing using a sample of Chinese A-share listed companies. The key findings include the following: (1) Specialized agglomeration inhibits corporate greenwashing through a “supervision” effect generated by intra-industry competition, while diversified agglomeration exacerbates greenwashing via a “collusion” effect arising from inter-industry cooperation. (2) The inhibitory role of specialized agglomeration is amplified under conditions of low public and strong government environmental concern, while the promotional effect of diversified agglomeration becomes more pronounced in contexts of high public and weak government environmental concern. Government environmental concern can be categorized into “general” and “specific” types, with the former being more effective in governing corporate greenwashing. (3) Specialized agglomeration demonstrates superior efficacy in curbing greenwashing among firms with green innovations related to energy-saving, alternative energy production, waste management, and transportation, while diversified agglomeration intensifies greenwashing tendencies in firms without green innovations. (4) Collusive greenwashing under diversified agglomeration yields short-term firm value gains but incurs hidden costs, including elevated operational risks and declining profit margins. This research provides critical insights for promoting corporate green transition and fostering zero-carbon industrial clusters. Full article

The aim of this study is to determine the effect of the separation of solid waste at the source on three different sustainable solid waste management scenarios using the analytic hierarchy process. In this context, the type of source separation method that would be most appropriate for three solid waste management scenarios was investigated (A1: material recycling facility + sanitary landfill; A2: material recycling facility + biological processes + sanitary landfill, and A3: thermal processes + biological processes + sanitary landfill) based on well-known solid waste management alternatives. Firstly, solid waste management scenarios were determined as decision points. Secondly, three solid waste collection options at the source (mixed: there is only one type of bin for all solid waste components; binary: paper + metal + plastic + glass, kitchen organics, and others; and triple: paper + metal + plastic + glass, kitchen organics, and others) were chosen as the main criteria affecting the decision points. Thirdly, fifteen sub-criteria were chosen based on the main criteria. In the process, not only the main and sub-criteria, but also stakeholders’ contributions are vital. For the pairwise comparison of all the criteria to be used in the study, the opinions of thirteen experts as stakeholders were obtained through face-to-face interviews. Within the scope of the zero waste vision, with a focus on environmental protection, the analytical hierarchy process was applied via pairwise comparisons of decision points and factors affecting the decision points. According to the results, in the case of mixed collection at the source, high preference rates were obtained for A1 as the decision point in terms of environmental (0.665), economic (0.699), social (0.510), and technical (0.544) criteria. In the case of binary separation at the source, A1 has high preference rates as the decision point in terms of environmental (0.553), economic (0.673), social (0.507), and technical (0.632) criteria. In the case of triple separation at the source, it is calculated that the A1 alternative has the highest preference values as the decision point in terms of environmental (0.558), economic (0.669), social (0.514), and technical criteria (0.611). Hence, the determining factor in the efficient integration of sustainable waste management with smart technologies is how waste is managed at the source. It is hoped that the results obtained in this study within the scope of the zero waste vision will assist decision-makers during sustainable municipal solid waste management processes. Full article

Achieving net-zero carbon emissions, this study introduces a sustainable pathway for reducing strontium sulfate (SrSO₄) and celestite ore to strontium sulfide (SrS) using biofuels (biomethane, bioethanol) derived from agro-industrial waste and green hydrogen. Traditional SrSO₄ reduction methods, which rely on fossil-derived reductants like coal and operate at energy-intensive temperatures (1100–1200 °C), generate significant greenhouse gases and toxic byproducts, highlighting the need for eco-friendly alternatives. Experimental results demonstrate that bioethanol outperformed other reductants, achieving 97% conversion of synthetic SrSO₄ at 950 °C within 24 min and 74% conversion of natural celestite ore over 6 h. Remarkably, this bioethanol-driven process matches the energy efficiency of the conventional black ash method while enabling carbon neutrality through renewable feedstock utilization, reducing CO₂ emissions by 30–50%. By valorizing agro-industrial waste streams, this strategy advances circular economy principles and aligns with Mexico’s national agenda for sustainable industrial practices, including its commitment to decarbonizing heavy industries. This study contributes to sustainable development goals and offers a scalable solution for decarbonizing strontium compound production in the chemical industry. Full article

This study examines a range of aspects relating to the projected waste generation in Bihor County, Romania from 2020 to 2040, focusing on key milestones set for 2020, 2025, 2030, 2035, and 2040. The analysis incorporates socio-economic, macroeconomic, and demographic factors, along with household income, economic activities, and waste composition, in order to obtain accurate projections. Furthermore, this study evaluates the current state of waste management, identifies deficiencies, and proposes targeted objectives. The assessment methodology considers targets such as increasing waste reuse and recycling rates, reducing biodegradable waste landfilling, enhancing energy recovery, and improving separate waste collection systems. Three alternative waste management strategies are analyzed, including a “zero” alternative (i.e., maintaining the current system) and two investment-driven alternatives. The evaluation integrates both quantitative criteria—such as financial viability and environmental impacts—and qualitative factors, including market risk and adherence to circular economy principles. Through a comprehensive analysis, this study offers a robust foundation for strategic decision-making in the context of sustainable waste management and the efficient implementation of waste treatment practices in Bihor County. Full article

Microbial fuel cells (MFCs) are environmentally friendly energy converters that use electrochemically active bacteria (EAB) as catalysts to break down organic matter while producing bioelectricity. Traditionally, MFC research has relied on simple organic substrates, such as acetate, glucose, sucrose, butyrate, and glutamate, the production of which involves energy-intensive, CO₂-dependent processes and chemically aggressive methods. In contrast, nonconventional waste streams offer a more sustainable alternative as feedstocks, aligning with zero-waste and regenerative agricultural principles. This review highlights the potential of nonconventional organic wastes, such as fruit and vegetable wastes, raw human and livestock urine, and farm manure, as globally available and low-cost substrates for MFCs, particularly in household and farming applications at small-scale waste levels. Furthermore, complex waste sources, including hydrocarbon-contaminated effluents and lignin-rich industrial wood waste, which present unique challenges and opportunities for their integration into MFC systems, were examined in depth. The findings of this review reveal that MFCs utilizing nonconventional substrates can achieve power outputs comparable to traditional substrates (e.g., 8314 mW m⁻²–25,195 mW m⁻² for crude sugarcane effluent and raw distillery effluent, respectively) and even superior to them, reaching up to 88,990 mW m⁻² in MFCs utilizing vegetable waste. Additionally, MFCs utilizing hydrocarbon-containing petroleum sediment achieved one of the highest reported maximum power densities of 50,570 mW m⁻². By integrating diverse organic waste streams, MFCs can contribute to carbon-neutral energy generation and sustainable waste management practices. Full article

Grape pomace (GP) has gained attention for its potential to be valorized into functional foods due to its rich composition of bioactive compounds. In this work, GP has been exploited to develop plant-based mayonnaise alternatives and salad dressings. The influence of the water-to-oil ratio, percentage content of GP, lecithin, and vinegar on the viscosity and physical stability of the obtained emulsions have been investigated by the Design of Experiments. Two formulations, one high-oil (70%) and the second high-water (60%), were further studied for their potential applications. The selected samples were subjected to an accelerated stability test (60 °C for 21 days) to verify the influence of GP on oxidation protection. The high-water sample, combined with 8% GP, showed lower primary (peroxide value < 20 mEq O₂/kg fat) and secondary oxidation (anisidine value < 55) parameters than the high-oil sample, highlighting the GP antioxidant activity. The phenolic profile of all samples by HPLC was also determined. Lastly, a sensory analysis was conducted, showing the highest overall acceptability for the oil-rich sample. The obtained results contribute to highlighting the potentiality of GP in the formulation of healthy foods, adopting the zero-waste approach for the full exploitation of this underutilized resource. Full article

The coffee industry generates a large amount of waste that is difficult to treat due to its chemical composition, namely, the presence of caffeine and its derivatives, as well as recalcitrant molecules such as tannins (mainly condensed tannins or polymeric procyanidins), which make it an undervalued waste product. Procyanidins are compounds beneficial to human health and can be found in nature in fruit, grain, seeds, and beverages, among other foods. The zero-waste approach has allowed for the valorization of by-products from the food industry. Currently, coffee pulp is the target of research on extraction, purification, and alternative use. Research on the fungal degradation of procyanidins has emerged as an avenue for the efficient use of these by-products. In this study, the degradation and biotransformation of procyanidin is evaluated and comprises three steps: first, the extraction and partial purification of procyanidins from coffee pulp; second, the production of the potential procyanidin-degrading enzyme by submerged fermentation with Aspergillus niger GH1; third, enzymatic extracellular extract evaluation using a model system with commercial procyanidin C1. The biodegradation/biotransformation results reveal the formation of new compounds, including a final compound with an m/z of 289, possibly a monomeric molecule such as catechin or epicatechin. Identification of the compounds by HPLC-MS confirmed procyanidin C1 depletion under the described assay conditions, which could be used to understand biodegradation pathways proposed for future study. Furthermore, these results confirm that A. niger GH1 is able to degrade and biotransform procyanidin C1. Full article

The global need for energy has risen sharply recently. A global shift to clean energy is urgently needed to avoid catastrophic climate impacts. Hydrogen (H₂) has emerged as a potential alternative energy source with near-net-zero emissions. In the African continent, for sustainable access to clean energy and the transition away from fossil fuels, this paper presents a new approach through which waste energy can produce green hydrogen from biomass. Bio-based hydrogen employing organic waste and biomass is recommended using biological (anaerobic digestion and fermentation) processes for scalable, cheaper, and low-carbon hydrogen. By reviewing all methods for producing green hydrogen, dark fermentation can be applied in developed and developing countries without putting pressure on natural resources such as freshwater and rare metals, the primary feedstocks used in producing green hydrogen by electrolysis. It can be expanded to produce medium- and long-term green hydrogen without relying heavily on energy sources or building expensive infrastructure. Implementing the dark fermentation process can support poor communities in producing green hydrogen as an energy source regardless of political and tribal conflicts, unlike other methods that require political stability. In addition, this approach does not require the approval of new legislation. Such processes can ensure the minimization of waste and greenhouse gases. To achieve cost reduction in hydrogen production by 2030, governments should develop a strategy to expand the use of dark fermentation reactors and utilize hot water from various industrial processes (waste energy recovery from hot wastewater). Full article

Succinic acid is applied in many chemical industries in which it can be produced through microbial fermentation using lignocellulosic biomasses. Mixed-waste office paper (MWOP) containing lignocellulosic fibers is enormously generated globally. MWOP is recycled into toilet paper and cardboard, but the recovery process is costly. The reuse of MWOP to alternatively produce succinic acid is highly attractive. In this study, pretreatment of MWOPs with 1% (v/v) H₂SO₄ at 121 °C for 20 min was found to be optimal. The optimal conditions for the enzymatic hydrolysis of H₂SO₄-pretreated MWOP (AP-MWOP) were at 50 °C, with cellulase loading at 80 PCU/g AP-MWOP. This resulted in the highest glucose (22.46 ± 0.15 g/L) and xylose (5.11 ± 0.32 g/L). Succinic acid production via separate hydrolysis and fermentation (SHF) by Escherichia coli KJ122 reached 28.19 ± 0.98 g/L (productivity of 1.17 ± 0.04 g/L/h). For simultaneous saccharification and fermentation (SSF), succinic acid was produced at 24.58 ± 2.32 g/L (productivity of 0.82 ± 0.07 g/L/h). Finally, succinic acid at 51.38 ± 4.05 g/L with yield and productivity of 0.75 ± 0.05 g/g and 1.07 ± 0.08 g/L/h was achieved via fed-batch pre-saccharified SSF. This study not only offers means to reuse MWOP for producing succinic acid but also provides insights for exploiting other wastes to high-value succinic acid, supporting environmental sustainability and zero-waste society. Full article

This study investigates the application of pipe freeze crystallization (PFC) as a sustainable, zero-waste technology for treating high-salinity industrial wastewater, enabling the simultaneous recovery of salts and clean water. PFC addresses the limitations of traditional brine treatment methods such as evaporation ponds and distillation, which are energy-intensive, produce concentrated brine requiring disposal, and emit significant CO₂. A pilot demonstration plant in Olifantsfontein, South Africa, served as the basis for this research. The plant operates at an energy consumption rate of 330 kJ/kg, significantly lower than distillation’s 2200 kJ/kg. It efficiently recovers high-purity Na₂SO₄ and clean ice, which can be reused as water, with plans underway to incorporate NaCl recovery. Comparative analyses highlight PFC’s energy efficiency and reduced CO₂ emissions, achieving an 82% reduction in greenhouse gas emissions compared to evaporation-based methods. This study evaluates the operational parameters and scalability of PFC for broader industrial applications. X-ray Diffraction analysis confirmed that the Na₂SO₄ recovered from the pilot plant achieved a purity level of 84.9%, demonstrating the process’s capability to produce valuable, market-ready by-products. These findings reinforce PFC’s potential as a cost-effective and environmentally sustainable alternative to conventional methods. PFC offers a transformative solution for managing saline effluents, aligning with zero-waste objectives and contributing to reduced environmental impact. This technology provides industries with an economically viable solution for resource recovery while supporting compliance with stringent environmental regulations. Full article