Life cycle assessment for municipal solid waste management: a case study from Ahvaz, Iran

Simultaneous achievement of energy recovery and carbon sequestration through municipal solid waste management: A review

Effective municipal solid waste (MSW) management is a crucial component for sustainable cities, as inefficient waste disposal contributes to the release of about a billion tons of CO2-eq in greenhouse gases (GHG) annually. With escalating global waste generation, there is an untapped opportunity to integrate carbon dioxide removal (CDR) technologies into existing MSW management processes. This review explores current research on utilizing MSW for CDR, emphasizing its potential for both energy generation and carbon sequestration. The investigation covers three waste management practices: landfilling, waste-to-energy (WtE), and biochar production, revealing two paths for carbon sequestration. First, MSW serves as a feedstock in bioenergy with carbon capture and storage (BECCS), acting as a carbon-neutral resource that avoids fossil fuel and energy crop use, reducing GHG emissions and generating value through energy production. Second, direct storage of organic MSW and its derivatives, like biochar, in various carbon sinks allows for extended sequestration, offering a comprehensive approach to address the challenges of waste management and climate change mitigation. Moreover, this review advocates for an extended exploration into several subjects including in-depth analysis of waste, research on MSW-derived biochar recalcitrance across different carbon sinks, and understanding the symbiotic connections with GHG-emitting sectors like agriculture and energy. Finally, this review emphasizes the necessity of conducting life-cycle assessment studies to fully discern the benefits and assess the impacts of any future endeavors exploring the role of MSW in carbon sequestration.

Life cycle assessment of municipal solid waste generated from hilly cities in India - A case study

Improper disposal of waste poses a grave environmental threat, contributing to pollution of air, water, and soil. It is necessary to address this issue in order to mitigate the adverse effects of solid waste on both the environment and public health. In many developing nations, municipal authorities of bigger cities are enduring significant challenges in proper management of waste. The present study evaluates the impacts of various waste management alternative scenarios for environmental impacts for the selected study locations using Life Cycle Assessment (LCA) methodology. The methodology comprised of five different scenarios of waste management including an existing baseline scenario. In this context, the environmental impact categories analyzed were Global Warming potential (GWP), Acidification potential (AP), Eutrophication potential (EP) and Human Toxicity potential (HTP). The results indicated that amongst all the proposed scenarios, Scenario 1 and 4 exhibited the maximum and minimum environmental impacts respectively. The study revealed that least greenhouse gas emissions, acidification potential, eutrophication potential and human toxicity potential were comparatively lesser for scenario 4 varying from 5.65 to 11.36 kg CO2eq t-1; 1.24-3.345 kg SO2eq t-1, EP 0.19-0.68 kg PO4eq t-1, and 0.35-4.22 kg 1,4-DBeq t-1 respectively. Further, a sensitivity analysis was also performed to evaluate the influence of recycling rate of valuable resources in all the considered scenarios. The sensitivity analysis indicated an inversely proportional relation between change in recycling rate and total environmental burdens.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

The Role of the Circular Economy in Road Transport to Mitigate Climate Change and Reduce Resource Depletion

The transport sector is responsible for several environmental impacts, including contributions to climate change through greenhouse gas emissions and depleting natural resources. A strategy to reduce these issues goes towards the application of a circular economy, a concept that offers a response to increasing concerns about resource scarcity and the associated impacts from their use. Thus, this paper aims to fill a gap in the literature that consists of the scarcity of studies that consider the circular economy application on a micro, meso, and macro level in road transport, including all stages as well as the 7 Rs of the reverse cycle. Therefore, an approach is presented to meet road transport needs, highlighting best practices obtained through a literature review, to promote climate change mitigation and resource depletion. Qualitative data were presented for each circular economy stage with 46 best practices identified, providing invaluable guidance to transport decision-makers. Thus, public policies focusing on all of the CE stages should be taken into consideration, not only those responsible for closing the cycle, such as waste and recycling or disposal and treatment.

Building new paths for responsible solid waste management

The amount of solid waste produced across the planet in the past decade was 1.3 billion tons (1.2 kg/year per person). Also, the significant number of publications on solid waste management (SWM) draws attention to the importance of discussing the topic to improve public health and to mitigate environmental impacts. The objectives of this article are to identify the state of the art and the scientific gaps on SWM and to propose a framework to promote it in the coming years. For this, a content analysis was carried out with the support of a bibliometric study, considering articles published in the Scopus database. The field of SWM study was classified into 12 different themes, and from this division, it was sought to identify the evolution of each of them between the 2005 and 2018 period. Content analysis and bibliometric study indicate that thermal and biological treatments are a promising trend to improve the performance of SWM. Its most important applied contribution is the generation of qualified information about SWM that can support the decision-making of public and private managers to reduce environmental impacts and improve life in urban spaces. The main academic contribution of the paper is the articulation of the most important themes on SWM, identifying the individual impact of each one of them in this field of study and the indication of the scientific trends that should guide the development of future research.

Drivers of Residents’ Home Composting Intention: Integrating the Theory of Planned Behavior, the Norm Activation Model, and the Moderating Role of Composting Knowledge

Home composting is judged as an effective municipal waste management option in which household contribution is essential, but it has a low adoption. The objectives of the study were to determine the factors that influence home composting intention and identify the moderating role of composting knowledge in the model, using the combined model of the theory of planned behavior (TPB) and norm activation model (NAM). A structured questionnaire was applied to a sample of 367 residents of Isfahan city, Iran, randomly selected. Data were analyzed using cluster analysis, discriminant analysis, PLS-SEM, and PLS-MGA. Cluster analysis grouped the three clusters based on the constructs of the integrated model, and this result was confirmed by discriminant analysis. Findings show that attitude, subjective norm, and perceived behavior control can predict the intention to compost. Study results confirmed the positive effect of awareness of the consequences of composting on ascribed responsibility to compost at home, of responsibility to the personal norm, and of the personal norm on intention to compost at home. Furthermore, it was observed that composting knowledge moderates the relationship between subjective norm and behavioral intention, and the one between perceived behavioral control and behavioral intention. The integrated model had more predictive power than the TPB model. The fit statistic of the integrated model was good and 71% of the variance for intention behavior toward home composting. The insights on factors affecting residents’ intention to compost obtained from this study can be used in measures and programs that reinforce and stimulate home composting.

Sensitivity analysis and improvements of the recycling rate in municipal solid waste life cycle assessment: Focus on a Latin American developing context

The life cycle assessment (LCA) of municipal solid waste (MSW) systems in developing countries is a matter of research. Obtain reliable results is challenging since field data and local databases are not always available. The research presented in this paper explores this issue in La Paz (Bolivia), where six environmental impact categories were assessed. The LCA, related to the formal MSW management system of the city, involves a sensitivity analysis of ten parameters and the scenario assessment in relation to the increase of the recycling rate. Results report that the environmental impacts are mostly sensitive in relation to landfill gas collection efficiency, use of plastic bags, the transportation distances of collected waste, and the replacement rate of virgin materials. Global warming potential is the impact category most variable (341.38-551.95 kg CO₂-eq t_MSW^-1), although it is not considerably reduced by recycling, which contributed mostly to the human toxicity and freshwater aquatic ecotoxicity. Doubling the amount of MSW recycled, from 235 t to about 473 t per year, human toxicity potential reduces of about 18% while freshwater aquatic ecotoxicity of about 12%. This research contributes for evaluating the most sensitive parameters in an MSW-LCA and to support policymakers towards waste recycling and sustainable development in Latin America developing cities.

Life Cycle Impact Assessment of Garbage-Classification Based Municipal Solid Waste Management Systems: A Comparative Case Study in China

Confronted with a series of problems caused by surging generation of municipal solid waste (MSW), the Chinese central and local governments have promulgated and implemented policies to deal with them, including promotions of the classification of MSW. However, to date, practical knowledge and understanding about benefits for garbage classification from its environmental performance perspective is still limited. The present study is purposed to comprehensively investigate the environmental effects of garbage classification on municipal solid waste management (MSWM) systems based on three proposed garbage classification scenarios in China, via a comparative life cycle impact assessment (LCIA). Taking advantage of Impact Assessment of Chemical Toxics (IMPACT) 2002+ method, this comparative LCIA study can quantitatively evaluate midpoint, endpoint, and single scored life cycle impacts for the studied MSWM systems. A Monte Carlo uncertainty analysis is carried out to test the effectiveness and reliabilities of the LCIA results. The LCIA and uncertainty analysis results show that MSWM systems based on various garbage classification scenarios have significant variations in the studied midpoint, endpoint, and single scored environmental impacts. Different garbage classification scenarios have their individual environmental-friendly superiority for specific impact categories. Overall, results of this study demonstrate that MSW treatment systems integrated with garbage classification are more environmentally friendly by comparison with non-classification; and that the more elaborate the level of MSW classification, the smaller its impacts on the environment.

Odour Emissions of Municipal Waste Biogas Plants—Impact of Technological Factors, Air Temperature and Humidity

Biogas plants processing municipal waste are an important part of a circular economy (energy generation from biogas and organic fertiliser production for the treatment of selectively collected biowaste). However, the technological processes taking place may be associated with odour nuisance. The paper presents the results of pilot research conducted at six municipal waste biogas plants in Poland. It shows the relations between odour intensity and concentration and the occurring meteorological and ambient conditions (air temperature and relative humidity) and technological factors at biogas plants processing municipal waste. The impact of meteorological and ambient conditions was identified by measuring air temperature and relative humidity and observing their changes. The impact of technological factors was identified by measuring odorant concentration (volatile organic compounds and ammonia) and observing their changes between individual measurement series. At most analysed biogas plants, the influence of technological factors on odour emissions took place and was clearly noted. The elements of biogas installations characterised by the highest concentration of these odorants were indicated. Special attention should be paid to the choice of technological solutions and technical and organisational measures to reduce the impact of unfavourable atmospheric conditions on odour emissions.

Enhancing waste management strategies in Latin America under a holistic environmental assessment perspective: A review for policy support

Waste remains a serious environmental and human health hazard in developing nations, including those in Latin America and the Caribbean (LA&C). Despite important breakthroughs in waste management in LA&C, the region still faces many challenges that require special attention, such as the existence of uncontrolled open dumpsters (33%) or the low recovery rates of waste fractions (below 4%). Moreover, the adoption of sophisticated waste management technologies, such as incineration or anaerobic digestion, is still lagging. This review paper provides environmentally-sound and relevant policy support for municipal solid waste management stakeholders through a critical review of the current situation of the waste management sector in LA&C from an environmental perspective. Thereafter, Life Cycle Assessment (LCA) bibliography linked to waste management, namely collection, sorting, recycling and landfilling applications and technologies worldwide, is used in order to understand potential alternative waste management strategies in LA&C, as well as the potential environmental benefits that could be attained. Finally, based on the holistic review and analysis, the adoption of more sophisticated technologies in landfill sites (e.g. landfill gas flaring), waste-to-energy, as well as higher recycling rates, would enhance waste management in the region and mitigate environmental impacts. A holistic view to support policy formulations, including climate action, for the adoption of integrated waste management strategies in LA&C is imperative.

Application of the Operational Research Method to Determine the Optimum Transport Collection Cycle of Municipal Waste in a Predesignated Urban Area

This paper deals with waste management. The aim is to find out whether the number of municipal mixed waste bins can be reduced due to the impact of waste separation and to determine the optimum municipal waste collection cycle within a predesignated area with an existing urban road network. The number of mixed waste bins depends on two factors—household waste volume and household waste composition. Both of these factors have a significant impact on the number of mixed waste bins required, with household waste composition being of particular importance when it comes to calculating the potential reduction in the number of mixed waste bins required due to waste separation. The calculations for the weight and volume of mixed household waste per person and the composition (types) thereof are presented accordingly. The results reveal which types of waste are the most useful in minimising the number of mixed waste bins by up to 30–50%. To determine the optimum waste collection cycle within the predesignated area with a real urban road network, the Nearest Neighbour Search method was applied. In the discussion, the focus is on whether other methods, including the Two-Phase Heuristic approach and the Bellman-Ford Algorithm, could be applied to solve the problem, whereby parameters such as application time and the capacity of the waste collection vehicle are compared.