Search Results (63)

This review investigates the influence of European Union regulations on the adoption of artificial intelligence in smart city solutions, with a structured emphasis on regulatory barriers, technological challenges, and societal benefits. It offers a comprehensive analysis of the legal frameworks in effect by 2025, including the Artificial Intelligence Act, General Data Protection Regulation, Data Act, and sector-specific directives governing mobility, energy, and surveillance. This study critically assesses how these regulations affect the deployment of AI systems across urban domains such as traffic optimization, public safety, waste management, and energy efficiency. A comparative analysis of regulatory environments in the United States and China reveals differing governance models and their implications for innovation, safety, citizen trust, and international competitiveness. The review concludes that although the European Union’s focus on ethics and accountability establishes a solid basis for trustworthy artificial intelligence, the complexity and associated compliance costs create substantial barriers to adoption. It offers recommendations for policymakers, municipal authorities, and technology developers to align regulatory compliance with effective innovation in the context of urban digital transformation. 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

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

The composition of plastic and multilayer packaging waste was assessed in the mixed municipal solid waste (MSW) streams of the Kaunas (Lithuania), Daugavpils (Latvia) and Tallinn (Estonia) municipalities. For the analysis of samples in the mixed MSW streams, the authors used manual sorting and a visual recognition method. Composition analysis of plastic and multilayer packaging waste from separately collected waste of multi-family and single-family households was performed in the Kaunas and Tallinn municipalities. For the analysis of samples in the separately collected waste streams, the research group combined manual sorting and near-infrared (NIR) spectroscopy methods. The findings reveal that the percentage distribution of plastic and multilayer packaging waste within the municipal solid waste (MSW) stream is relatively consistent across the municipalities of Kaunas, Daugavpils and Tallinn, comprising 40.16%, 36.83% and 35.09%, respectively. However, a notable variation emerges when examining separately collected plastic and multilayer packaging waste streams. In this category, the proportion of plastic and multilayer packaging within the total separately collected packaging waste stream ranges from 62.05% to 74.7% for multi-family residential buildings and from 44.66% to 56.89% for single-family residential buildings. The authors provided further insights for the enhanced recycling potential of different plastic materials through improved sorting. Full article

Enhancing the eco-efficiency of municipal solid waste (MSW) services is pivotal for the shift toward a circular economy. Although the Data Envelopment Analysis (DEA) method is widely used, it is susceptible to overfitting, potentially distorting eco-efficiency assessments. This study applies the efficiency analysis tree (EAT) method, which synergizes machine learning and linear programming, offering a more reliable framework for eco-efficiency evaluation in the MSW sector. This innovative approach provides deeper insights into the optimal levels of operational costs and unsorted waste. The research encompasses a case study of 98 Chilean municipalities from 2015 to 2019, uncovering significant disparities in optimal operational expenses and unsorted waste quantities, which underscores the necessity for customized waste management approaches. The average eco-efficiency scores for 2015–2019 range between 0.561 and 0.566. This means that assessed municipalities can reduce unsorted waste by amounts ranging from 1,632,409 tons/year (2016) to 1,822,663 tons/year (2018). Potential economic savings estimated are 105,973 USD/year (2019), which represents 44% of the total MSW management costs. Additionally, the investigation into the effects of external factors on eco-efficiency furnishes nuanced perspectives that can guide policymakers and municipal authorities in developing effective, context-specific waste management strategies. Beyond refining eco-efficiency evaluations, this study contributes to more informed decision-making processes, aiding the progression toward sustainable waste management practices. Full article

The increasing production of solid waste and the scarcity of natural aggregates as a matter of fact have made waste recycling a necessity. One such waste, which is generated in large quantities, is slag. However, slag from incineration plants may contain harmful elements that adversely affect the physical, chemical and mechanical properties of cement composites. This study presents laboratory research results on the effect of slag from the Poznan Municipal Waste Thermal Conversion Plant (Poland) on the physicochemical properties of cement composites. The samples were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that the slag analyzed contained significant amounts of aluminum, which had a direct effect on the structure of the concrete. An example of this influence is the release of hydrogen during reactions, which causes swelling and cracking of the concrete and reduces its mechanical strength. The authors emphasize that waste aggregate (slag) can be effectively used in the production of concrete after appropriate processing that reduces the risk of adverse effects. Full article

In Africa, the urban population and informal settlements are increasing, resulting in additional public health and environmental risks and challenges related to the need for basic and sustainable infrastructures and services. In Maputo, the capital of Mozambique, at least 80% of the city is composed of informal settlements, and although some areas are regularized and have approved urbanization plans, the municipality has major deficiencies in meeting current demands in terms of basic infrastructures, such as water supply, sewerage, solid wastes, energy, roads, and communications. Most of the peri-urban areas are occupied by small but overcrowded houses, mostly self-built, served by unpaved roads, and with access limitations. The water pipe network is almost non-existent, and the same occurs with stormwater drainage, sanitation, waste collection, and public illumination services. Despite the improvements made in the last few years, some households still do not have safe sanitation, and in some neighborhoods, open defecation still prevails. In this study, the authors try to understand and explore the interdependences among the infrastructures of the different sectors and how they may jointly contribute to adequate services and a better life for the urban poor. And how to identify the combination of infrastructures to be implemented in the short term in the face of limited budgets for investments. For that purpose, a simplified conceptual approach is proposed and applied to an informal neighborhood in Maputo. Full article

The pursuit of shifting Slovakia towards a circular economy is met with a multitude of obstacles, including the pervasive consumerist mindset among Slovakians. This mindset favors packaged food, leading to its improper disposal in municipal waste instead of being recycled. Furthermore, the inclination towards landfills poses a significant challenge in the management of municipal solid waste (MSW). To address this issue, a quantitative analysis was conducted using developed and validated models, incorporating various factors related to MSW management in Slovakia. Our study confirmed the significance of parameters such as MSW management costs and population size in the amount of MSW generated. Furthermore, our findings include a short-term forecast for MSW generation in Slovakia for the next two years. These results, based on quantitative data, provide valuable insights for policymakers and waste management authorities in Slovakia, emphasizing the urgent need for a transition towards a more sustainable and circular economy. Full article

Rapid population growth, urbanization, and diverse production materials have led to a surge in municipal solid waste (MSW), harming the environment, climate, and sanitation. Despite China’s efforts to implement MSW segregation policies, results have been unsatisfactory. Research often emphasizes public participation, with less focus on the entire policy implementation process. This paper employed Smith’s theoretical model to comprehensively analyze the challenges of implementing a MSW segregation policy, using qualitative methods and secondary data from literature and policy documents. The findings revealed challenges at four levels: policy formulation, implementing agencies, target groups, and the external environment. Issues include policy ambiguity, unclear authority, government-enterprise cross-functionality, casual attitudes, implementer shortages, poor public participation, and economic disparities. To address these, the study recommends enhancing public engagement, clarifying responsibilities among agencies, and increasing financial support for disadvantaged areas to improve policy implementation. Full article

This study is motivated by the need to understand and proffer sustainable circular economy solutions to the persistent challenges associated with plastic waste management in Nigeria. Despite the emerging awareness and increased number of studies conducted on plastic and plastic products in Nigeria, the challenges and opportunities associated with their production, consumption, and post-consumption management are still poorly understood. Besides the large quantity of plastic and plastic products produced locally in Nigeria, a substantial quantity of these products in various forms and polymer types also comes into the country through importation. This results in a high consumption rate and, by extension, a huge volume of plastic waste generated daily exceeding the capacity and ability of the authorities to manage. In this work, we reviewed the available literature to analyze the status of the production, importation, consumption, and post-consumption management of plastic waste in Nigeria. It is estimated that out of 27.3 million tonnes of municipal solid waste currently generated in Nigeria’s urban cities per annum about 11.2 million tonnes is collected, of which about 1.1 million tonnes is plastics. It is further projected that by 2040, about 40.5 million tonnes of municipal solid waste will be generated, and only about 1.6 million tonnes of the plastic component will be collected for disposal. Based on the outcome of the analysis, the current study further suggested how adopting circular economy principles can help mitigate the impact of plastic waste on Nigerian society. Full article

This paper presents an innovative mathematical model of solid fuel gasification, which is not described in the available literature. The calculation of the components of the heterogeneous phase (including both solid and gaseous phases) as well as the calculation of the homogeneous phase (only gaseous components) is based on the balance of the total amounts of carbon, oxygen, hydrogen, and nitrogen entering the reactor space. Additionally, this paper introduces a new method for calculating the composition of the gaseous phase, based on reducing the heterogeneous mixture (composed of solid and gaseous phases) to a homogeneous gaseous phase. This approach to calculating the gaseous phase composition in the solid fuel gasification process has not been found by the authors in the cited literature. This paper also presents a model for calculating the heterogeneous and gaseous phases using the number of moles that participate in the assumed chemical reactions of the solid fuel gasification process. This approach to calculating the composition of the heterogeneous and gaseous phases of the solid fuel gasification process is also not represented in the cited literature. For comparison with the literature data, municipal solid waste (MSW) and cashew nut shell (Cashew Shell Char (CNSC)) were used as fuels in the calculation of gasification composition. The results of the calculation of the gaseous phase composition using the model presented in the paper show good agreement with the data from the literature. The calculation of the composition of the heterogeneous mixture during the steam gasification of MSW (α = 0.4) shows the presence of a solid phase (carbon) up to approximately 735 °C. At that temperature, the synthetic gas contains only gaseous components: CO = 33.10%, H₂ = 52.70%, CH₄ = 2.54%, CO₂ = 4.97, H₂O = 5.93% and N₂ = 0.76%. Increasing the temperature above 735 °C eliminates the solid phase from the equilibrium mixture. The literature data on solid fuel gasification generally do not consider the proportion of the solid phase (carbon) in the equilibrium mixture. To satisfy the material balance at the input and output of the gasification reactor, it is necessary to determine the proportion of the solid phase (carbon) in the equilibrium mixture. Since the proportion of the solid phase (carbon) in the heterogeneous equilibrium mixture can only be determined through measurement, the development and application of a mathematical model in engineering practice is of great importance, so this developed model can be considered a useful tool for simulating the influence of process parameters on gas characteristics. Full article

Indigenous knowledge systems related to solid waste management in economically marginalized communities have been largely overlooked in the scientific literature, even though the indigenous communities of developing nations struggling to manage solid waste rely on these practices. It is startling that indigenous solid waste management practices are scarcely documented in the scientific literature despite their position as potential alternative disposal methods. This gap persists amid limited municipal budgets, inadequate waste collection services, and poor infrastructure in economically marginalized indigenous rural communities in developing nations. Subsequently, in the discipline of solid waste management, this obstacle impedes the recognition and inclusion of indigenous waste management practices into integrated waste management plans. As a result, this causes a delay in their progress or elevation to the same level of credibility as mainstream scientific knowledge. In the process, this relegates the waste management practices of indigenous communities to the background. Against this background, the current study sought to investigate the indigenous solid waste management practices of rural communities in Bushbuckridge Local Municipality. As such, ten cases that captured the spatial cultural diversity of indigenous communities’ practices across Bushbuckridge Local Municipality (BLM) were selected for sampling. Data were collected using ethnographic research methods. Data analysis was carried out using the thematic analysis approach. Inductive logic was used in the interpretation of the current study results. The results of the current study indicate that indigenous communities of Bushbuckridge Local Municipality, in the absence of formal waste management services from the local authority, resort to an indigenous knowledge system to manage solid waste. Waste burning (100%), open-air dumping (100%), and backyard pits (90%) are some of the indigenous waste management practices espoused by the rural communities of BLM. The similarity in practices was corroborated by statistical inferences that revealed that between BLM communities, the amount of indigenous waste management practices is not significant (p > 0.05). However, there are concerns that despite the sustainability aspect associated with recycling (<25%) practices, these disposal methods are not common in the rural communities of BLM. This is a setback for an indigenous knowledge system that is supposed to advance environmental sustainability practices. Full article

Anaerobic digestion (AD) is a promising biowaste valorization technology for sustainable energy, circular economy, local energy community growth, and supporting local authorities’ environmental goals. This paper presents a systematic review meta-analysis methodology for biomethane estimation, using over 600 values of volatile solids (VS) content and biochemical methane potential (BMP) of six different waste streams, collected from 240 scientific studies. The waste streams include cow manure (CM), sheep/goat manure (SGM), wheat straw (WS), household waste (HW), organic fraction of municipal solid waste (OFMSW), and sewage sludge (SS). The statistical analysis showed a mean VS content of 11.9% (CM), 37.3% (SGM), 83.1% (WS), 20.8% (HW), 19.4% (OFMSW), and 10.6% (SS), with BMP values of 204.6, 184.1, 305.1, 361.7, 308.3, and 273.1 L CH₄/kg VS, respectively. The case study of Kozani, Greece, demonstrated the methodology’s applicability, revealing a potential annual CH₄ production of 15,429,102 m³ (corresponding to 551 TJ of energy), with SGM, WS, and CM as key substrates. Kozani, aiming for climate neutrality by 2030, currently employs conventional waste management, like composting, while many local business residual streams remain unused. The proposed model facilitates the design and implementation of AD units for a sustainable, climate-neutral future. Full article

In Indonesia, plastic constitutes the second largest component of municipal solid waste; however, 58% remains uncollected. Most plastic recycling depends on informal sectors, accounting for only 10% of the total, leaving the remainder to potentially harm the environment. This paper analyzes how cities in Indonesia have tackled their plastic waste problems from the perspective of the integrated sustainable waste management framework. This study focuses on plastic waste management (PWM) in three cities: Bandung, Yogyakarta, and Magelang. Data were collected from 41 semi-structured interviews, a plastic waste composition data analysis, and site visits. The research outcomes include a comprehensive analysis of stakeholder roles, plastic waste flow, plastic waste composition data, and various challenges in PWM. This study identifies three main stakeholders in collecting plastic wastes: the Department of Environment as the main local government body, community-based waste banks, and private waste management companies. Most recyclable plastic waste is recovered through waste banks and private collection services. In 2022, the predominant types of plastic waste in Bandung, Yogyakarta, and Magelang City were soft plastics, thick plastics, and hard plastics, respectively. The challenges for the PWM stem from various aspects in political, legal, and institutional; environmental; financial and technical; and socio-cultural spheres. Positive trends towards an integrated system are observed, although full integration has not yet been achieved. The research recommends a multi-stakeholder cooperative approach involving municipal authorities, waste banks, and private collectors, responsive to local conditions and emphasizing sustainability aspects throughout waste management stages for a sustainable resource recycling in developing countries. Full article

In order to protect the natural resources, it is beneficial for the environment when materials that are not valuable, such as waste or recycled materials, are used in engineering. This article presents laboratory studies on the use of mixtures of incineration bottom ash (IBA) from municipal waste incinerators with natural, fine grain and uniform aggregate in cement-bound layers. The mechanical and engineering properties of aggregates were studied, their usefulness was assessed and possible applications are indicated. The chemical composition of the material was found to be consistent with typical IBA from other incineration plants, and leachability studies were carried out, confirming lack of any environmental impact. The authors’ own mixtures were prepared based on optimal water content and maximal dry densities of solid particles, and the compressive strength was calculated after 7 and 28 days of hardening. The results indicate that replacing natural aggregates with IBA permits an increase in the compressive values for the specimens using the same amount of CEM I 42.5R while improving the frost resistance of cement–aggregate mixtures. Full article