Search Results (345)

Gasification of municipal solid waste and other biogenic residues (e.g., biomass and biowaste) is increasingly recognized as a promising thermochemical pathway for converting non-recyclable fractions into valuable energy carriers, with applications in electricity generation, district heating, hydrogen production, and synthetic fuels. This paper provides a comprehensive analysis of major gasification technologies, including fixed bed, fluidized bed, entrained flow, plasma, supercritical water, microwave-assisted, high-temperature steam, and rotary kiln systems. Key aspects such as feedstock compatibility, operating parameters, technology readiness level, and integration within circular economy frameworks are critically evaluated. A comparative assessment of incineration and pyrolysis highlights the environmental and energetic advantages of gasification. The valorization pathways for main product (syngas) and by-products (syngas, ash, tar, and biochar) are also explored, emphasizing their reuse in environmental, agricultural, and industrial applications. Despite progress, large-scale adoption in Europe is constrained by economic, legislative, and technical barriers. Future research should prioritize scaling emerging systems, optimizing by-product recovery, and improving integration with carbon capture and circular energy infrastructures. Supported by recent European policy frameworks, gasification is positioned to play a key role in sustainable waste-to-energy strategies, biomass valorization, and the transition to a low-emission economy. Full article

Automated waste classification is an essential step toward efficient recycling and waste management. Traditional deep learning models, such as convolutional neural networks, rely on extensive labeled datasets to achieve high accuracy. However, the annotation process is labor-intensive and time-consuming, limiting the scalability of these approaches in real-world applications. Zero-shot learning is a machine learning paradigm that enables a model to recognize and classify objects it has never seen during training by leveraging semantic relationships and external knowledge sources. In this study, we investigate the potential of zero-shot learning for waste classification using two vision-language models: OWL-ViT and OpenCLIP. These models can classify waste without direct exposure to labeled examples by leveraging textual prompts. We apply this approach to the TrashNet dataset, which consists of images of municipal solid waste organized into six distinct categories: cardboard, glass, metal, paper, plastic, and trash. Our experimental results yield an average classification accuracy of 76.30% with Open Clip ViT-L/14-336 model, demonstrating the feasibility of zero-shot learning for waste classification while highlighting challenges in prompt sensitivity and class imbalance. Despite lower accuracy than CNN- and ViT-based classification models, zero-shot learning offers scalability and adaptability by enabling the classification of novel waste categories without retraining. This study underscores the potential of zero-shot learning in automated recycling systems, paving the way for more efficient, scalable, and annotation-free waste classification methodologies. Full article

The accelerated industrialization in China has precipitated a dramatic surge in solid waste generation, causing severe land resource depletion and posing substantial environmental contamination risks. Simultaneously, the cement industry has become characterized by the intensive consumption of natural resources and high carbon emissions. This review aims to investigate the current technological advances in utilizing industrial solid waste for cement production, with a focus on promoting resource recycling, phase transformations during hydration, and environmental management. The feasibility of incorporating coal-based solid waste, metallurgical slags, tailings, industrial byproduct gypsum, and municipal solid waste incineration into active mixed material for cement is discussed. This waste is utilized by replacing conventional raw materials or serving as active mixed material due to their content of oxygenated salt minerals and oxide minerals. The results indicate that the formation of hydration products can be increased, the mechanical strength of cement can be improved, and a notable reduction in CO₂ emissions can be achieved through the appropriate selection and proportioning of mineral components in industrial solid waste. Further research is recommended to explore the synergistic effects of multi-waste combinations and to develop economically efficient pretreatment methods, with an emphasis on balancing the strength, durability, and environmental performance of cement. This study provides practical insights into the environmentally friendly and efficient recycling of industrial solid waste and supports the realization of carbon peak and carbon neutrality goals. Full article

The modern world has brought extensive socioeconomic and ecological changes. Urbanization in developing nations has significantly increased municipal solid waste, necessitating in-depth understanding of waste composition particularly in developing nations for sustainable management practices. This study aimed to classify and characterize waste while evaluating potential waste management methods. Mixed methods were used to examine landfilled waste from Soshanguve and Hatherley sites in Tshwane Metropolitan, South Africa, using techniques such as Fourier transform infrared spectroscopy, X-ray fluorescence, proximate, and ultimate analysis. Seasonal variations in waste components were analysed over two seasons. The study identified that both sites are predominantly composed of organic waste, accounting for over 42 wt.%, with moisture content of ~50 wt.%, and minimal recyclables (<5 wt.%). Seasonal variations in MSW were significant for glass (<4% increase), organic waste (<5% increase), while plastic decreased by ~7% during spring. The biodegradable waste showed high carbon (>50%) and oxygen (>40%) levels, low ash content (<18%), and calorific values of 15–19 MJ/kg. Biodegradables mainly contained oxides of calcium, silicon, iron (III), and potassium with chemical composition indicating functional groups that emphasize composting and energy recovery benefits. The research provides insights into sustainable waste management, revealing waste composition at Tshwane landfills, aiding informed decision-making for resource usage and environmental conservation. Full article

Textile recycling approaches require input material streams of defined purity. Establishing sorting facilities and defining viable sorting fractions for efficient subsequent recycling necessitates knowledge on the composition and material content of the textiles to be processed. Subsequently, this information is crucial for the implementation of a sustainable circular economy for textiles. This study presents the results of a comprehensive waste textile sampling and characterisation along with data on the quantities and composition of waste textiles in Vienna in 2022. The data reveals that only 28% of the 19,975 t of waste textiles generated end up in separate collection, of which a significant amount goes to the international market. However, the results regarding the fibre composition show that textiles from mixed municipal solid waste and separate collection are very similar. Cotton fibres accounted for approx. half of the fibre mass from non-complex textiles, with 9328 t overall (6776 t in the mixed municipal solid waste and 2522 t in separate collection). A further analysis regarding fibre blends found that a total of 6275 t of single-fibre materials and 5132 t of two-fibre materials were present. This reveals great potential for using this waste stream in fibre-to-fibre recycling processes. Collecting accurate data on this waste stream enables sorters and recyclers to tailor their processes to the expected input material. By increasing the amount of recycled materials, the share of incinerated or landfilled textiles will decrease, which in turn will have a positive impact on the environment. However, further research in textile identification and material separation as well as regulations to keep these materials in a sustainable closed loop are required. Full article

The municipal solid waste generation is projected to spike from 2.1 billion tonnes in 2023 to 3.8 billion tonnes by 2050. In Taiwan, the upsurge of waste volume, in addition to periodic maintenance of incinerators, which may persist up to four months, has resulted in limited incineration capacity. The optimum approach to address the challenge is to reduce the amount of waste sent for incineration by effective segregation of combustible and non-combustible waste, as well as improving the public recycling rate. Local authorities play a significant role in encouraging public recycling and restricting non-burnable waste from being delivered to incinerators within a short period of time. This can greatly reduce the amount of waste and incinerator maintenance costs. This study aimed to explore the key driving factors for public participation in waste recycling and translate the determinants into policy in order to increase the waste recycling rate. The study employed literature analysis to select factors repeatedly mentioned as indicators and conducted online surveys to collect data on factors influencing consumer engagement in waste recycling in Taiwan. This study also adopted the Analytic Hierarchy Process and established a hierarchical framework with four dimensions (Psychological, Knowledge, Policy, and Infrastructure) and thirteen indicators. The findings have demonstrated that infrastructure (0.275) is the most influential aspect in affecting consumers’ recycling actions, followed by psychological (0.256) and policy aspects (0.251), and knowledge aspect (0.218) as the least influential factor. Positive rewards (0.120), recycling knowledge (0.118), and well-built infrastructure (0.113) were specifically identified as key drivers in encouraging recycling. The findings informed the public’s priorities in recycling involvement, and strategic initiatives targeted at these preferences can effectively assist local authorities in promoting citizen engagement in recycling. Policies that meet public demands, such as positive rewards for recycling, dissemination of recycling knowledge, and provision and improvement of more recycling infrastructure, can ensure the success of the policy implementation and serve as a reference for other Asian countries in reducing waste and improving the recycling rate. Full article

Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews often focus narrowly on specific technologies or regional case studies, lacking a comprehensive analysis of global research trends. This study addresses this significant gap by conducting a large-scale trend analysis based on 15,646 relevant articles screened from 25,068 Scopus-indexed publications from 1904 to 2023 using title, abstract, and keyword analysis. Literature-based comparative assessments were conducted to critically evaluate the pathways through TEE (techno-economic and environmental), SWOT (strengths, weaknesses, opportunities, and threats), and PESTEL (political, economic, social, technological, environmental, and legal) frameworks. Since 1990, article publication has increased by about 10% annually, consistently concentrating on thermochemical conversion and, more recently, on sustainability and circular economy perspectives. Seven distinct pathways for MSW management were identified, with recycling and material recovery, followed by thermochemical conversion for high-calorific waste and biochemical conversion for high-organic waste, showing the most promise. The findings aim to help researchers understand MSW research trends and assist planners in identifying effective management and valorization strategies. Full article

The use of mineral waste for the production of lightweight artificial aggregate is an important element of activities for sustainable development in construction and the implementation of the objectives of the circular economy. The article presents the physical, mechanical, and ecological properties of an innovative artificial aggregate produced from bottom sediments, concrete dust, and municipal solid waste incineration fly ash. The obtained research results confirm that the developed material achieves technological properties comparable to artificial aggregates available on the market, both commercial and those derived from recycling. However, the increased leachability of chlorides and sulphates remains a significant challenge, which may limit the scope of its applications. Despite this, the material shows the potential for use, among others, in the production of lightweight concrete. The analyses carried out have shown that the thermal hardening processes (200–400 °C) and autoclaving do not guarantee full immobilization of harmful substances contained in the raw materials for the production of this type of aggregate. Full article

This study employed a two-stage fixed-bed pyrolysis-reforming reactor to investigate H₂ production behaviors from municipal solid waste (MSW) and biomass with their self-derived catalysts under different operating parameters. The self-derived catalysts are prepared by mechanically mixing pyrolysis-derived chars with CaO and iron powders. The main results are as follows: (1) The higher oxygen content in biomass facilitates oxidative dehydrogenation reactions, enabling in situ generation of H₂O, which results in a higher H₂/CO ratio for biomass compared to MSW under steam-free conditions. (2) There are optimal values for the reforming temperature and steam-to-feedstock ratio (S/F) to achieve best performance. In the presence of steam, MSW generally exhibits superior H₂ and syngas production performance to biomass; (3) Both MSW char (MSWC)- and biomass char (BC)-based catalysts showed satisfied H₂ production and tar cracking performance at 850–900 °C, and the MSWC-based catalyst demonstrated better catalytic activity than the BC-based catalyst due to its higher contents of several active metals. In addition, the iron powder can be recycled easily, proving the effectiveness of the self-derived convenient and cheap catalysts. Full article

This study investigates the effectiveness of the Lagos Recycle Initiative (LRI) on landfill diversion (LFD) in Lagos, Nigeria, where evidence-based assessments of such initiatives are lacking. It evaluates the recycling diversion rate (RDR) of household recyclables (HSRs) across local government areas using field surveys and population data. Machine learning algorithms (logistic regression, random forest, XGBoost, and CatBoost) refined with Bayesian optimisation were employed to predict household recycling motivation. The findings reveal a low RDR of 0.37%, indicating that only approximately 2.47% (31,554.25 metric tonnes) of recyclables are recovered annually compared to a targeted 50% (638,750 metric tonnes). The optimised CatBoost model (accuracy and F1 score of 0.79) identified collection time and the absence of overflowing HSR bins as key motivators for household recycling via the SHapley Additive exPlanations (SHAP) framework. This study concludes that current LRI efforts are insufficient to meet recycling targets. It recommends expanding recovery efforts and addressing operational challenges faced by registered recyclers to improve recycling outcomes. The policy implications of this study suggest the need for stricter enforcement of recycling regulations, coupled with targeted financial incentives for both recyclers and households to boost recycling participation, thereby enhancing the overall effectiveness of waste diversion efforts under the LRI. This research provides a benchmark for assessing urban recycling initiatives (RIs) in rapidly growing African cities. Full article

Global municipal solid waste (~2B tons/year) affects sustainability, as landfill and incineration face persistent leachate contamination, demanding effective management to advance water recycling and circular economies. Accelerated investigation of hybrid biocatalytic ozonation systems is imperative to enhance contaminant removal efficiency for stringent discharge compliance. This study investigates the catalytic ozonation effects of γ-Al₂O₃-based catalysts loaded with different metals (Cu, Mn, Zn, Y, Ce, Fe, Mg) on the biochemical effluent of landfill leachate. The catalysts were synthesized via a mixed method and subsequently characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Pseudo-second-order kinetics revealed active metal loading’s impact on adsorption capacity, with Cu/γ-Al₂O₃ and Mg/γ-Al₂O₃ achieving the highest Q_e (0.85). To elucidate differential degradation performance among the catalysts, the ozone/oxygen gas mixture was introduced at a controlled flow rate. Experimental results demonstrate that the Cu/γ-Al₂O₃ catalyst, exhibiting optimal comprehensive degradation performance, achieved COD and TOC removal efficiencies of 84.5% and 70.9%, respectively. UV–vis absorbance ratios revealed the following catalytic disparities: Mg/γ-Al₂O₃ achieved the highest aromatic compound removal efficiency; Ce/γ-Al₂O₃ excelled in macromolecular organics degradation. EEM-PARAFAC analysis revealed differential fluorophore removal: Cu/γ-Al₂O₃ exhibited broad efficacy across all five components, while Mg/γ-Al₂O₃ demonstrated optimal removal of C2 and C4, but showed limited efficacy toward C5. These findings provide important insights into selecting catalysts in practical engineering applications for landfill leachate treatment. This study aims to elucidate catalyst formulation-dependent degradation disparities, guiding water quality-specific catalyst selection to ultimately enhance catalytic ozonation efficiency. 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

With the increasing rate of urbanization and the annual rise in municipal domestic waste, the use of harmless municipal solid waste incineration fly ash (HMSWIFA) as a construction material has been gradually adopted and promoted. However, significant differences exist in how various characteristics of HMSWIFA affect the performance of recycled aggregate concrete (RCA). To analyze the effects of HMSWIFA content and particle size on the macroscopic properties and microstructure of RCA, this paper conducts compressive, flexural, frost resistance, and Scanning Electron Microscope (SEM) characterization on RCA with varying dosages and particle sizes of HMSWIFA as a cement replacement. The results indicate that HMSWIFA enhances the compressive strength (CS) and frost resistance of RCA. Experimental data reveal that HMSWIFA with a particle size of 600–900 μm exhibits the best modification effect at an admixture level of 10–15%: the 28-day CS increased by 1.90–3.60%, the mass loss after freezing and thawing decreased by 0.37–0.45%, and the increase in dynamic elastic modulus reached 16.09–16.44%. Notably, the flexural strength (FS) experienced a reduction of 1.81% at a high dosage of the optimal particle size. This study elucidates the coupling relationship of “particle size-admixture-performance” in HMSWIFA-modified recycled concrete, demonstrating that reasonable control of the particle size distribution of HMSWIFA can achieve a synergistic effect of mechanical enhancement and durability improvement. The research findings provide a valuable reference for the application of municipal waste incineration HMSWIFA in RCA, facilitating the recycling of waste resources to mitigate pollution and enhance energy efficiency. Full article

Municipal solid waste (MSW) accumulation is a critical global challenge for society and governments, impacting environmental and social sustainability. Efficient separation of MSW is essential for resource recovery and advancing sustainable urban management practices. However, manual classification remains a slow and inefficient practice. In response, advances in artificial intelligence, particularly in machine learning, offer more precise and efficient alternative solutions to optimize this process. This research presents the development of a light deep neural network called R3sNet (three “Rs” for Reduce, Reuse, and Recycle) with residual modules trained end-to-end for the binary classification of MSW, with the capability for faster inference. The results indicate that the combination of processing techniques, optimized architecture, and training strategies contributes to an accuracy of 87% for organic waste and 94% for inorganic waste. R3sNet outperforms the pre-trained ResNet50 model by up to 6% in the classification of both organic and inorganic MSW, while also reducing the number of hyperparameters by 98.60% and GFLOPS by 65.17% compared to ResNet50. R3sNet contributes to sustainability by improving the waste separation processes, facilitating higher recycling rates, reducing landfill dependency, and promoting a circular economy. The model’s optimized computational requirements also translate into lower energy consumption during inference, making it well-suited for deployment in resource-constrained devices in smart urban environments. These advancements support the following Sustainable Development Goals (SDGs): SDG 11: Sustainable Cities and Communities, SDG 12: Responsible Consumption and Production, and SDG 13: Climate Action. Full article

An increasing lack of raw materials, resource depletion, environmental impacts and other concerns have changed the way the population faces garbage disposal and municipalities implement waste management strategies. The aggravated global rise in municipal solid waste (MSW) generation has led to a new stage in full development, with objectives and targets set by the European Union regarding reducing the production of MSW. The targets also include the increasing selective collection, reuse, recycling and recovery (organic and energetic) of the waste produced. At the same time, the European Union has also set caps for the greenhouse gas emissions and for increasing the use of alternative renewable energy sources. In this context, one of the sources of renewable energy that is beginning to be used to produce electricity in our country is biogas. Finally, AD promotes the development of a circular economy. The present study introduces the formalism for a computer application that simulates the technical–economic behaviour of the short-term management of biogas for the conversion of electricity, and the mathematical model is formulated as a mathematical programming problem with constraints. A simulation for a case study of short-term management is given using the real landfill data available. The case study proves the ability of the LandGEM, despite some authors’ support that the Tabasaran–Rettenberger model provided a more reliable estimate, especially when compared to actual landfill data. The present paper is a contribution to the optimisation of the management of electricity from the use of biogas, namely the second phase of the Strategic Plan for Urban Waste. In addition to complying with the legislation in force, the use of biogas to produce electricity is an added value for the concessionaires of waste treatment and final destination units, as this alternative energy source can provide not only self-sufficiency in electricity for these units but also the export of surplus energy to the National Electricity Grid, thus contributing to the self-sustaining management and energy flexibility that is intended for these infrastructures. Full article