Circular Economy最新文献

Mega sporting events (MSEs) such as the FIFA World Cup and the Olympics always attract people around the world to visit the hosting country, boosting its tourism and business, and leaving a positive legacy. However, such events also leave significant negative impacts on the environment such as an increase in greenhouse gas (GHG) emissions in the host and neighboring countries. Considerable research efforts have been devoted to reducing such negative impacts and maintaining the sustainability of infrastructure associated with MSEs. The infrastructure construction in the host country of an MSE is the main and inevitable source of GHG emissions. In particular, the construction work of stadiums. This study presents comprehensive research on scope-based carbon footprint analysis related to two phases, i.e., the construction phase and operation phase of stadiums, by taking the eight world cup stadiums in Qatar as a case study. A life cycle assessment is used to quantify the potential environmental impacts of these stadiums at different stages. The Ecoinvent database is used to quantify the emission factor at each phase. According to the findings, Scope 3 (indirect supply chain) emissions are greater than Scope 1 (direct on-site) emissions, and the construction supply chain is found to be a significant contributor to the carbon footprint of the stadiums, accounting for 98% of the total GHG emissions. The results also show that electricity, district cooling, and waste generation are the three top contributors of GHG emissions with 35%, 25%, and 21% emissions, respectively. Moreover, it is vital to implement innovative approaches such as circular design for end-of-life material recycling and reuse of structural components, which can support a transition toward sustainable and carbon-neutral mega events. Thus, this study presents the role of circular economy in achieving carbon-neutral FIFA World Cup Qatar 2022. This research will contribute to enhancing the future benefits of the sustainable construction of infrastructure projects for mega events and help in harmonizing mega event strategies with national circular economy targets.

PV modules generally contain several metals that are considered critical and/or strategic and can be recovered. They also contain harmful and toxic metals that pose a threat to the environment and human health, which makes the significance of recycling even greater. This study used mechanically processed waste Si–C (polycrystalline silicon) photovoltaic (PV) panels to obtain highly concentrated recycled metals of interest. The PV panels were comminuted and granulometrically separated before the concentration of the metals of interest could be studied in an electrostatic separator. Some parameters of the electrostatic separator were evaluated, such as the applied voltage, rotation speed of the roll, as well as distance and angle of the electrodes for better separation of the metals of interest (copper, silver, aluminum, and silicon). The results were evaluated by X-ray fluorescence analysis and the proportions of each element in the samples were compared. The results obtained showed that in the comminution and particle size separation process, the greatest mass of material (49.22%) is concentrated in the smallest particle size category, which is smaller than 0.5 mm. This particle size also has higher concentrations of silicon, silver, and aluminum. The best results with the electrostatic separator were obtained using an electric potential difference of 38 kV and a rotation speed of 75 rpm (rotation per minute), where it was possible to concentrate silicon, silver, and aluminum.

To improve the effectiveness of recycling, echelon utilization, and recovery mechanism of waste power batteries (WPBs), 12 recycling modes were proposed based on extended producer-responsibility principle. By employing profit and sensitivity analyses, we found that resource-recovery companies (Rs) are the key for recycling, echelon utilization, and recovery mechanism. For R, the high resale price of waste LiNi_xMn_yCo_1−x−yO₂ batteries was not conducive to recovering waste batteries. However, the recycling behavior of R was beneficial for resisting the risk of high resale price of waste LiNi_xMn_yCo_1−x−yO₂ batteries. This condition increased the profits by saving on the buying cost and reselling of WPBs to echelon-utilization companies. Following the decrease in the number of recyclers in the recycling system, the profits of R also increased. However, when the proportion of recycled waste LiNi_xMn_yCo_1−x−yO₂ batteries was 100%, the profits of R faced risks due to the high resale price of waste LiNi_xMn_yCo_1−x−yO₂ batteries. For other recyclers, only the power-battery manufacturers (Ms) were willing to reduce the resale price of waste LiNi_xMn_yCo_1−x−yO₂ batteries to let R earn profit because R supplied regenerated materials to M at a lower price than the material companies. This condition created a cycle for WPB recovery and reduced the use of raw materials. Thus, Mode M–R was considered as the optimal recycling mode.

Under the goal of global sustainable development, the new energy vehicle industry is evolving rapidly, leading to a proliferation of spent lithium-ion batteries (LIBs). The recycling of LIBs is key to the sustainable development of the new energy industry, which is consistent with the concept of circular economy as well. And the green extraction of critical metals is the core part of the development. As an alternative to traditional pyrometallurgy and hydrometallurgy, emerging mechanochemical technology provides a new approach for high efficiency and green recycling of critical metals from spent LIBs, as it has the advantages of easy operation, flexibility, and short processing time. This article reviews the state of the art of mechanochemical technology in the recycling of critical metals from spent LIBs. Based on numerous practices, a framework including mechanochemical activation, organic reaction, inorganic reaction, redox reaction, gas-solid reaction, and solid-phase synthesis was constructed. These practices have proved that mechanochemical technology can provide a greener and more sustainable solution for recycling critical metals from spent LIBs. The metals can be transformed into high-value metal products at room temperature and under ordinary pressure, leading to efficient recycling of critical metals and significant reduction of wastes.