Circular Economy最新文献

As the main consumer group for online shopping and ordering fast food, young people—particularly university students—have contributed to a substantial amount of packaging waste. In the present study, the material flow method was employed to quantify the generation and end-of-life flows of packaging waste from both the express delivery and food delivery sectors at universities in China. Moreover, this study takes reusable packaging materials for food delivery services as a case study to evaluate their environmental benefits through a simplified life cycle assessment approach. The results show that approximately 1.7 (±0.3) million metric tons and 123 (±1.0) kilo metric tons of packaging waste were generated from express delivery and food delivery services, respectively, for university students in 2021. Although reusable food packaging is more complex and costly than regular disposable food packaging is, our modeling results show that reusable food packaging has significant emission reduction benefits under the current practice of 63 cycles per year of actual operation at a specific university. The reusable packaging mode in universities is feasible from an environmental perspective; however, it faces significant challenges due to a few concerns among stakeholders, such as high costs and inadequate recycling supply systems.

The urgent global challenges of climate change and resource overconsumption highlight the need for sustainable innovations in the construction industry. Ordinary Portland cement, a vital construction material, significantly contributes to carbon emissions. Alkali-activated materials have emerged as promising alternatives. Three-dimensional printing (3DP) has gained attention in construction, because it offers efficiency and sustainability benefits. This study addresses the integration of alkali-activated materials and 3DP, focusing on circular economy implications. This study examines 1200 research articles from the Scopus database and comprehensively reviews 47 articles on 3DP of geopolymer structures. This study identifies critical research gaps, including a lack of focus on 3DP for alkali-activated materials, circular economy models, optimal mixtures, anisotropy mitigation, reinforcement strategies, and scalability. These insights highlight the transformative potential of 3DP with alkali-activated materials in sustainable construction, fostering a circular economy.

Malachite green is a persistent, bioaccumulative, mutagenic, carcinogenic, and teratogenic dye that poses significant risks in water sources, making its removal from water a critical necessity. This study aims to fabricate a sorbent comprising amorphous aluminosilicate nanopowder utilizing silicomanganese slag (SMS) and secondary aluminum dross (SAD) waste materials to remediate dye-contaminated water. The silica and alumina components of the SMS and SAD were extracted as sodium silicate and sodium aluminate leachates, respectively, through an effective hydrometallurgical conversion process. An empirical formula of Al₂O₃·2.3SiO₂ was deduced from the X-ray fluorescence analysis of the synthesized material. The X-ray diffraction (XRD) pattern indicated the amorphous nature of the synthesized aluminosilicate, with no evidence of nanocrystals or ordered clusters observed via high-resolution transmission electron microscopy (TEM). Based on TEM micrographs, the aluminosilicate particles ranged in size from 20 to 80 nm. The synthesized aluminosilicate nanopowder was utilized to treat wastewater containing malachite green dye, demonstrating a remarkable dye removal efficiency of 97% after a 15-min contact time using 30 mg of adsorbent in a 30 mL dye solution at 200 rpm. The methodology proposed in this study could facilitate the production of amorphous aluminosilicate powder as a high-value product from industrial waste. Studies on its reusability demonstrated that it could remove over 90% of the dye after three cycles of use.

Hazardous waste from industrial production has become a global concern because of its impact on the environment and human health. However, studies on heavy metals in regional hazardous waste are rare. Thus, this study examined 93 hazardous waste samples in Beijing in 2019, to assess the distribution, occurrence, and potential eco-environmental risks of heavy metals in such waste. The results indicated high concentrations of Zn, Cu, and Ni in hazardous waste, and the leaching toxicity of Ni (270.60 mg/L), Cu (524.1 mg/L), and Pb (136.23 mg/L) exceeded Chinese identification standards for hazardous waste. Heavy metals in hazardous waste have been primarily found in remote counties around the locations of industrial enterprises. The total amount of the heavy metals followed the order: Zn > Cu > Ni > Ba > Mn > Pb. Based on the migration abilities of their detected forms, heavy metals were classified into three categories (high, middle, and low migration abilities) to characterize their potential to enter the environment. The detected amounts of heavy metals with high and middle migration ability followed the order: Zn > Cu > Ni > Mn > Pb > Ba. The potential environmental risk of heavy metals was evaluated using the potential environmental risk index, resulting in the following ranking: Ni > Pb > Mn > Zn > Cu > Ba. Daxing District exhibited the highest total environmental risk and environmental risk per unit area, whereas Miyun District showed the highest environmental risk per secondary sector of the economy and unit of GDP. This was attributed to Beijing's industrial structure. The results of this study provide fundamental data for the management and control of hazardous waste in Beijing and are expected to aid in preventing and managing environmental risks caused by such waste.

The wastewater circular economy promises improved environmental impacts within the food-water-energy nexus. This requires verification as the global sanitation sectors seek to improve environmental impacts and achieve integrated water management. Life cycle assessment (LCA) has been used to compare novel technologies for wastewater treatment and recovery, but research addressing plant-wide improvements of co-product resource recovery using real data from full-scale plants is still needed, particularly in a Latin American context. In Chile, two wastewater treatment plants (WWTPs) have embraced the circular economy configuration, recovering treated effluent, biosolids, and biogas, in addition to implementing advanced nitrogen removal using different technologies. The LCA of these two WWTPs demonstrated that Plant A improved 8 out of 10 impact categories compared to the baseline conventional scenario, while Plant B improved 5 categories out of 10. The analysis of the two plants showed the influence of influent quality on environmental impacts and the trade-off that occurs between the different technologies implemented. Plant B generated larger environmental credits through increased biogas and biosolids recovery due to thermal hydrolysis pre-treatment and anaerobic digestion, combined with cogeneration of heat and power. Plant A implemented water recovery, which provided benefits on a smaller magnitude but to more impact categories. Therefore, both plants improved environmental impacts through the wastewater circular economy, but further improvements in system configurations are recommended in each.

In recent years, the chemical production and waste generation have been rapidly increasing, presenting substantial hazards to the ecosystem and human well-being. To address this issue, a series of multilateral environmental agreements (MEAs) have been developed internationally, that provide essential decision-making support for the appropriate governance of chemicals and wastes in the participating countries. MEAs have established subsidiary bodies known as science-policy interface (SPI) institutions to provide evidence-based support and scientific assessments for environmental policies. However, the existing SPIs face limitations that hinder their ability to tackle the obstacles presented by the vast quantities of chemicals and wastes currently found in the environment. Therefore, the fifth session of the United Nations Environment Assembly made the decision to establish a science-policy panel to promote the effective management of chemicals and waste and to prevent pollution (SPP-CWP). This panel is intended to be an independent intergovernmental body, similar to the Intergovernmental Panel on Climate Change and Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. The United Nations Environment Programme convened an ad hoc open-ended working group (OEWG) to design strategies for the SPP-CWP. Since 2022, three OEWG meetings have been conducted, and draft documents outlining the panel's scope, functions, operational principles, conflict of interest policy, institutional setup, work processes, and procedures have been formulated. In this article, we analyzed the background and development of the SPP-CWP and provided updates regarding the progress of the panel's establishment. We also suggested future trends for the SPP-CWP. We concluded that SPP-CWP will be a comprehensive and authoritative international body, providing policymakers with exhaustive reports, consequently strengthening the capacity of life cycle management of chemicals. Thus, the panel will effectively reduce or prevent waste production and pollution, promote material circulation, and minimize resource consumption, making significant contributions to the establishment of a circular economy and an environmentally friendly society.

Biological treatment technologies (such as anaerobic digestion, composting, and insect farming) have been extensively employed to handle various degradable organic wastes. However, the inherent complexity and instability of biological treatment processes adversely affect the production of renewable energy and nutrient-rich products. To ensure stable processes and consistent product quality, researchers have invested heavily in control strategies for biological treatment, with machine learning (ML) recently proving effective in optimizing treatment, predicting parameters, detecting disturbances, and enabling real-time monitoring. This review critically assesses the application of ML in biological treatment, providing an in-depth evaluation of key algorithms. This study reveals that artificial neural networks, tree-based models, support vector machines, and genetic algorithms are the leading algorithms in biological treatment. A thorough investigation of the applications of ML in anaerobic digestion, composting, and insect farming underscores its remarkable capacity to predict products, optimize processes, perform real-time monitoring, and mitigate pollution emissions. Furthermore, this review outlines the challenges and prospects encountered in applying ML to biological treatment, highlighting crucial directions for future research in this area.