Multi-Criteria Decision Making Approaches Applied to Waste Electrical and Electronic Equipment (WEEE): A Comprehensive Literature Review

Experimental and Molecular Dynamics Simulation Insights into Adsorption of Co(II), Cr(III), and Cu(II) on Chitosan and Chitosan/Tripolyphosphate Nanoparticles

Chitosan (CS)/tripolyphosphate (TPP) nanoparticles were synthesized using the ionic gelation method based on the mass ratio and volume ratio between CS and TPP and then subsequently characterized using XRD, FT-IR, and SEM. The interaction between the metal ions Co(II), Cr(III), and Cu(II) on CS and 2CS/TPP was simulated using molecular dynamics (MD), and the findings were compared with the experimental data. CS/TPP nanoparticles were more favorable than using pure chitosan at a % removal efficiency of 91.47, 89.11, and 78.11 for Cu(II), Cr(III), and Co(II), respectively. The binding energy between 2CS/TPP and the metals was more favorable than that for CS at -214.95, -106.87, and -58.11 kcal/mol for Cr(III), Co(II), and Cu(II), respectively. The CS/TPP nanoparticles greatly affect metal adsorption and are therefore considered materials for wastewater treatment.

Challenges to implement and operationalize the WEEE reverse logistics system at the micro level

Waste electrical and electronic equipment (WEEE) possesses unique characteristics such as its growing production and the potential for resource extraction due to its composition. The implementation and operationalization of a reverse logistics system (RLS) for WEEE is a challenge, particularly concerning the micro level. The implementation of such systems often prioritizes urban centers and their higher population densities, generally overlooking the micro level. The latter refers to ward- or village-level divisions, which can be regarded as the smallest administrative divisions of both urban and rural areas. Furthermore, it encompasses any area facing logistical challenges regarding RLS operationalization due to factors such as geographical isolation, budgetary constraints, imbalances, social isolation, environmental aspects, and even geopolitical conflicts. This study is aimed at addressing this literature gap by discussing the challenges to implement and operationalize a WEEE RLS at the micro level. A systematic literature review was employed as our methodology. We found 13 challenges for developed and developing countries without distinction between macro and micro levels. An additional approach highlighted the significance of monitoring and controlling WEEE RLS. The challenge The population and LRS entities' lack or insufficient training and awareness received the most citations in the conducted search. These challenges were organized by operational phase and discussed from the perspective of the micro level to comprehend multifactorial local challenges involving all stakeholders in the reverse logistics of WEEE in emerging nations. This can assist local administrators and constitutes the primary contribution of this study.

Multi-criteria decision making-based waste management: A bibliometric analysis

Waste management is a complex research domain. While the domain is challenging in terms of content, it is also a diverse and cross-disciplinary research subject. One of its important components includes efficient decision-making at various levels and stages. Therefore, Multi-criteria decision-making (MCDM) techniques have found decent applications in this domain. The field of MCDM techniques-based waste management has been examined using bibliometric analysis in this paper in order to report a systematic overview of the trends and advancements in this area of study. The Scopus database provided 216 publications on the aforementioned subject written between 1992 and 2022. The 216 articles include 56 countries, 158 institutions, and 160 authors. Furthermore, Asian countries, including India, Iran, and China, dominate this field of study. The geographical disparity in the output of publications is visible. Journal of cleaner production, Waste Management and Waste Management and Research are the major journals publishing on MCDM techniques-based waste management research. Given that majority of the articles include multiple authors, it can be said that there is a lot of collaborative research in this area. Overall, the current study provides a thorough analysis of the development in the domain of waste management using MCDM techniques. The trend suggests that it will continue to be a focus of research for academicians, environmentalists and policymakers in the future.

Cloud Based Fault Diagnosis by Convolutional Neural Network as Time-Frequency RGB Image Recognition of Industrial Machine Vibration with Internet of Things Connectivity

The human-centric and resilient European industry called Industry 5.0 requires a long lifetime of machines to reduce electronic waste. The appropriate way to handle this problem is to apply a diagnostic system capable of remotely detecting, isolating, and identifying faults. The authors present usage of HTTP/1.1 protocol for batch processing as a fault diagnosis server. Data are sent by microcontroller HTTP client in JSON format to the diagnosis server. Moreover, the MQTT protocol was used for stream (micro batch) processing from microcontroller client to two fault diagnosis clients. The first fault diagnosis MQTT client uses only frequency data for evaluation. The authors' enhancement to standard fast Fourier transform (FFT) was their usage of sliding discrete Fourier transform (rSDFT, mSDFT, gSDFT, and oSDFT) which allows recursively updating the spectrum based on a new sample in the time domain and previous results in the frequency domain. This approach allows to reduce the computational cost. The second approach of the MQTT client for fault diagnosis uses short-time Fourier transform (STFT) to transform IMU 6 DOF sensor data into six spectrograms that are combined into an RGB image. All three-axis accelerometer and three-axis gyroscope data are used to obtain a time-frequency RGB image. The diagnosis of the machine is performed by a trained convolutional neural network suitable for RGB image recognition. Prediction result is returned as a JSON object with predicted state and probability of each state. For HTTP, the fault diagnosis result is sent in response, and for MQTT, it is send to prediction topic. Both protocols and both proposed approaches are suitable for fault diagnosis based on the mechanical vibration of the rotary machine and were tested in demonstration.

The evaluation of energy consumption in transportation and processing of municipal waste for recovery in a waste-to-energy plant: a case study of Poland

Refuse-derived fuel (RDF) can be produced from combustible materials contained in municipal waste. This article investigates energy and material flow of waste in different scenarios for production of RDF from bulky waste, separately collected waste, and mixed municipal solid waste (MSW). We compare the proportion of energy consumption in transportation, handling waste, and processing using data from the waste collection company in South Poland. The findings show the components of the reverse supply chain consuming the highest value of energy. A model of material and energy flow has taken into consideration collection of waste and transportation by two categories of waste collection vehicles: light commercial vehicles and garbage trucks. The shipping of RDF from pre-treatment facilities uses tipper semi-trailers and walking floor trailers. The findings of the study show production of RDF from municipal solid waste consumes almost 10% of energy potential in RDF. Less energy is required for the production of RDF from bulky waste (2.2-4.8%) or separately collected waste (1.7-4.1%) depending on the efficiency of collection and selected vehicles. Transportation consumes the greatest portion of energy. For mixed municipal solid waste (MSW), it can reach 79%; for separated collection waste, 90%; and for bulky waste, up to 92% of the total energy consumed. Comparing emissions for two categories of the collection vehicles, no significant difference was found for the bulky waste collections. For mixed MSW and separately collected waste, the emissions are higher for garbage trucks. A recommendation for practitioners is optimization of routing to achieve a higher collection rate at a minimized route length. For transportation of RDF to WtE plants, vehicles with higher loading capacity are essential.

Modification of the DIBR and MABAC Methods by Applying Rough Numbers and Its Application in Making Decisions

This study considers the problem of selecting an anti-tank missile system (ATMS). The mentioned problem is solved by applying a hybrid multi-criteria decision-making model (MCDM) based on two methods: the DIBR (Defining Interrelationships Between Ranked criteria) and the MABAC (Multi-Attributive Border Approximation area Comparison) methods. The methods are modified by applying rough numbers, which present a very suitable area for considering uncertainty following decision-making processes. The DIBR method is a young method with a simple mathematical apparatus which is based on defining the relation between ranked criteria, that is, adjacent criteria, reducing the number of comparisons. This method defines weight coefficients of criteria, based on the opinion of experts. The MABAC method is used to select the best alternative from the set of the offered ones, based on the distance of the criteria function of every observed alternative from the border approximate area. The paper has two main innovations. With the presented decision-making support model, the ATMS selection problem is raised to a higher level, which is based on a proven mathematical apparatus. In terms of methodology, the main innovation is successful application of the rough DIBR method, which has not been treated in this way in the literature so far. Additionally, an analysis of the literature related to the research problem as well as to the methods used is carried out. After the application of the model, the sensitivity analysis of the output results of the presented model to the change of the weight coefficients of criteria is performed, as well as the comparison of the results of the presented model with other methods. Finally, the proposed model is concluded to be stable and multi-criteria decision-making methods can be a reliable tool to help decision makers in the selection process. The presented model has the potential of being applied in other case studies as it has proven to be a good means for considering uncertainty.

Recycling Model Selection for Electronic Products Considering Platform Power and Blockchain Empowerment

This paper considers a dynamic platform-based, closed-loop supply chain consisting of a manufacturer and an online platform. As an online distributor of the manufacturer, the platform expands the market scale by exerting the platform power. At the same time, to solve the problem of inconsistency between the actual recycling amount and the theoretical recycling amount in the recycling process of waste electronic products, the whole-process supervision of waste products is carried out with the help of blockchain technology, which is difficult to tamper with and is traceable. With the help of differential game theory, four differential game models of manufacturer recycling and platform recycling with and without blockchain are established. The state feedback strategies are derived from Bellman’s continuous dynamic programming theory. Through analytical results and comparative analysis, the adoption conditions of blockchain and the impact of blockchain on the selection of recycling models are obtained. The results illustrated that the introduction of blockchain technology effectively improves the real recycling rate of waste electronics, building trust in consumers, which benefits corporations in certain conditions. However, it amplifies the double marginal effect of the CLSC. Nevertheless, the implementation of blockchain is still beneficial to consumers, as the adverse impact of the double marginal effect is compensated by the improvement in consumer surplus. In addition, the study shows that the implementation of the blockchain incentivizes members, who benefit on the same recycling model when the fixed cost of the blockchain and the share ratio of the residual value of waste electronics are between certain thresholds. That is, both the manufacturer and the platform are better off in a manufacturer recycling model enabled by blockchain. Moreover, in this model, the social welfare and the recycling rate of waste electronics are increased, which enable the CLSC to achieve benefits related to economy, environment, and society.

E-Device Purchase and Disposal Behaviours in the UAE: An Exploratory Study

The United Arab Emirates (UAE) is one of the high-income countries in the Middle Eastern region and is vying for sustainable development in every sector. One of the UAE sustainable development goals is to ensure sustainable consumption and production patterns; hence, the emphasis is on circular economy. UAE is one of largest consumers of e-devices, and their proper disposal is of paramount importance. E-waste disposal awareness leads to better disposal behaviors. Therefore, the purpose of the study was to understand the e-device purchase and disposal behaviour among university communities in the UAE. A survey was conducted among the students and staff members of a federally funded university in the UAE, namely Zayed University, and quantitative methodology was adopted to analyze the collected data. The study found that 47.95% of respondents purchased mobile phones, and 65% of the respondents purchased 1–3 electronic devices every year. Through chi-square test, gender of the respondents was found to be related with e-device ownership. Through the analysis of variance (ANOVA), age and field of specialization were found to affect the knowledge about e-waste. Older and the respondents with science specialization were more aware about e-waste. Most of the respondents disposed e-devices, such as batteries, earphones/headphones, and electronic toys, along with the household trash. A very small percentage of respondents disposed e-devices such as laptops, phones, and tablets with the household trash. Mostly, these were either repaired, donated, or sold to second-hand users. Many respondents were neither aware of the government initiatives on e-waste collection nor participated in government-sponsored e-waste recycling. The study further identified that 67% of the respondents were aware of the toxicity of e-waste, and 61% of the respondents were keen to join e-waste recycling drives at university. The findings of the study imply that the policy makers need to incentivize e-waste-disposal systems and develop targeted awareness approaches to enhance e-waste disposal in the UAE.

A Review on Global Emissions by E-Products Based Waste: Technical Management for Reduced Effects and Achieving Sustainable Development Goals

In the 21st century, a great amount of electrical and electronic waste (e-waste) has accumulated, and the unregulated nature of its disposal and recycling represents a particular hazard in a global context. For the purposes of e-waste management, there must be more emphasis on the scientific processes for recycling, reusing and remanufacturing precious materials. Resource management is related to energy management; therefore, the harvesting of costly materials from e-waste is important for both energy management and sustainable development. At present, a lack of scientific recycling of a significant amount of e-waste is a source of environmental pollution and health hazards that are having a detrimental effect on sustainable development goals. It is necessary to find a process for recovering valuable materials from e-waste with the minimum possible environmental impact. At present, it is essential to modify the process of electrical and electronic products (e-products) becoming e-waste, and the subsequent process of e-waste recycling, in order to lessen the impact in terms of pollution. E-waste scientific recycling initiatives can reduce the environmental impact of the process, which in turn can support a shift from the current linear flow of costly materials to a more sustainable circular flow. Furthermore, internal consumption loss, emissions, and heating loss from e-products are the main factors contributing to the loss of energy efficiency in the process, which in turn contributes to environmental pollution. Promoting green innovation in the manufacturing process of e-products, as well as their reuse, can reduce the environmental impact of e-waste in near future. Both of these pathways are imperative for a less polluted, low-toxic environment and sustainable development. However, the sustainable development initiative of the United Nation Environmental Programme (UNEP) policy framework is the ultimate goal. This is expected to support the management of environmental pollution, maintaining it at an acceptable level, while also preventing hazardous risks to human health. Hence, this review examines the prospects for achievable environmental sustainability through technological developments.

New Models to Reduce the Health Risks of Informal WEEE Recyclers in MTN Phone Village, Rumukurushi, Port Harcourt, Nigeria

Waste electrical and electronic equipment (WEEE) management in Port Harcourt, an oil-producing city in Nigeria, has become an environmental challenge for the location. WEEE recycling is predominantly managed by informal recyclers, who lack the skills to perform risk-free recycling, hence raising health risks to individuals in associated communities and degrading the environment. Formal recycling, which embraces the best practices for effective WEEE management, is faced with several limitations, such as a lack of detailed guidelines on waste recycling, reuse, and final disposal techniques, with no opportunities for landfilling. A qualitative approach was adopted for this study. Data were gathered via questionnaires and analysed graphically. A background literature review of the assessment of informal recycling methods and associated challenges was performed. Hence, a new concept for the local management of WEEE processing was introduced. This concept limits the role of informal recyclers to WEEE collection. In this case, informal recyclers are paid for WEEE collection; they no longer engage in further WEEE processing. The results show that 48% and 40% agree to partner and collaborate with government agencies, respectively. Conversely, 52% and 40% agree and strongly agree, respectively, to limit their activities to WEEE collection only if the government is willing to pay for the services.

Collecting Small-Waste Electrical and Electronic Equipment in Poland—How Can Containers Help in Disposal of E-Waste by Individuals?

The effectiveness of e-waste collection depends on organizational and social factors. Individuals should have easy access to collection points and be aware of proper methods of e-waste disposal. This article investigates the availability, usability, and occurring irregularities of the container collection of small-waste electrical and electronic equipment. The study explores the attitude and behavior of individuals when disposing of small-waste equipment in the South of Poland. The results show that ninety-five percent of supermarkets’ managers responsible for waste management find a growing interest in the disposal of small e-waste by individuals. An increasing number of collection containers encourages residents to dispose of small-waste appliances. More than eighty-three percent of respondents are aware of proper methods of e-waste disposal. Additional information campaigns addressed to residents are required to prevent mixing electrical and electronic waste with other waste and to encourage the disposal of small e-waste. The intention to dispose of small e-waste was declared by only thirty-two percent of respondents. Containers with discarded easy breakable items, such as lamps, should be removed more frequently. The collection containers’ noticeability is evaluated by individuals as of average difficulty. The containers in supermarkets have simple designs and labels indicating the category of waste for disposal. The containers installed in residential areas have attractive designs and advertising slogans. The individuals expect the containers should be available in more locations that are easily accessible from households. The results of this study should be helpful for local authorities, waste collection companies, and waste electrical and electronic organizations, to support design, location selection, and information campaigns for small e-waste container collections.

Pro-environmental behavior and smartphone uses of on-campus engineering students in Xi'an, China

BACKGROUND

The usage status, waste electrical and electronic equipment (WEEE) related to the smartphones of on-campus engineering students should be studied. Furthermore, the correlations between their smartphone profiles with energy consumption and environmental knowledge should be understood make measures improve their environmental behaviors.

METHODS

Pro-environmental behavior and smartphone uses of the on-campus engineering undergraduates in Xi'an, China, were investigated with a self-designed questionnaire anonymously. The energy-saving activities they participated in and their e-waste treatment patterns were analyzed.

RESULTS

Most of the respondents had a smartphone with large screen and high battery capacity, which also had long standby/usage time and frequent charging. Average daily power consumption of one smartphone was estimated to be 6.475 Wh. The surveyed undergraduate students changed their smartphones frequently, which produced large quantities of WEEE annually.

CONCLUSION

Most on-campus students treated their waste smartphones in the proper ways. However, some of them were short of environmental knowledge about their smartphones. Some measures were suggested to improve their environmental concerns. The findings will help the on-campus engineering undergraduates in China to use their smartphones rationally and to deal with their waste smartphones appropriately.

Sustainability Assessment of Reuse and Recycling Management Options for End-of-Life Computers-Korean and Japanese Case Study Analysis

The depletion of natural resources and global warming have increased in severity globally. In the industrial field, assembly products, such as electronic products, should be disassembled for recycling and reuse to deal with these problems. Reuse and recycling can contribute to reducing GreenHouse Gas (GHG) emissions and less depletion of natural resources since GHG emissions for virgin material production can be saved using reused components and recycled materials. However, each component of selling revenue and material-based GHG emissions depends on the country because of the different energy mixes of electrical power. Moreover, each collected component embedded in End-of-Life (EOL) products needs to be selected as a life cycle option based on its remaining life. The purpose of this study is to decide life cycle options such as reuse, recycling, and disposal of each component environmentally-friendly and economically in Korea and Japanese cases for computers. Firstly, selecting the life cycle option for each component was formulated by 0–1 integer programming with ε constraints. Next, GHG emissions, profits, and costs in Korea and Japan were estimated and analyzed for each component. Finally, Korean and Japanese cases were analyzed to obtain an economic value in the same material-based GHG saving rate with each component’s life cycle option selection by comparing each EOL product data. In the experiments, GHG recovery efficiency was higher in Japan 43 [g/Yen] than one in Korea 28 [g/Yen]. Therefore, it was better to retrieve and reutilize the components in Korea. However, if the maximum GHG recovery efficiency is desired, Japan is a better option.