Waste management最新文献

Green and biowaste, processed within large facilities into compost, is a key fertilizer for agricultural and horticultural soils. However, due to improper waste disposal of plastic, its residues often remain or even lead to the formation ofmicroplastics (1 µm - 5 mm, MiPs) in the final compost product. To better understand the processes, we first quantified 'macroplastics' (> 20 mm, MaPs) input via biowaste collection into an industrial composting plant, and, then determined MiP concentrations at five stages during the composting process (before and after shredding and screening processes), and in the water used for irrigation. The total concentrations of MaPs in the biowaste collected from four different German districts ranged from 0.36 to 1.95 kg ton^-1 biowaste, with polyethylene (PE) and polypropylene (PP) representing the most abundant types. The "non-foil" and "foil" plastics occurred in similar amounts (0.51 ± 0.1 kg ton^-1 biowaste), with an average load of 0.08 ± 0.01 items kg^-1 and 0.05 ± 0.01 items kg^-1, respectively. Only 0.3 ± 0.1 kg MaP t^-1 biowaste was biodegradable plastic. Compost treatment by shredding tripled the total number of MaPs and MiPs to 33 items kg^-1, indicating an enrichment of particles during the process and potential fragmentation. Noticeably, a substantial amount of small MiPs (up to 22,714 ± 2,975 particles L^-1) were found in the rainwater used for compost moistening, being thus an additional, generally overlooked plastic source for compost. Our results highlight that reducing plastic input via biowaste is key for minimizing MiP contamination of compost.

Bio-based and biodegradable (bio-)plastics are heralded as a key solution to mitigate plastic pollution and reduce CO₂ emissions. Yet, their end-of-life treatments embodies complex energy and material interactions, potentially leading to emissions through incineration or recycling. This study investigates the cradle-to-grave, emphasizing the waste management stage, carbon footprint for several types of bio-plastics, leveraging both GWP100a and CO₂ uptake methods to explore the carbon reduction benefits of recycling over disposal. Our findings indicate that in scenarios characterized by carbon-intensive electricity, using polylactic acid (PLA) as an example, incineration with energy recovery (-1.6316 kg CO₂-eq/kg, PLA) yields a more favorable carbon footprint compared to chemical recycling (-1.5317 kg CO₂-eq/kg, PLA). In contrast, in environments with a high proportion of renewable energy, chemical recycling is a superior method, and compared to incineration (-1.4087 kg CO₂-eq/kg, PLA), the carbon footprint of chemical recycling (-2.0406 kg CO₂-eq/kg, PLA) are significantly reduced. While mechanical recycling presents considerable environmental benefits, its applicability is constrained by the waste quality, especially in the case of biodegradable plastics like PLA. In addition, the degradation of biodegradable plastics such as PLA was modeled during compost and anaerobic digestion processes. This enables us to quantify the specific biogenic carbon emissions released during these processing steps, revealing the direct emissions with dynamic degradation. This study highlights the importance of tailoring bio-plastic waste management strategies to support global energy decarbonization while understanding their life-cycle carbon metabolism to effectively tackle plastic pollution and climate change.

Plastic Recovery Facilities are typically designed to process a specific, predetermined mix of plastic in the infeed. However, in many cases, the composition of the infeed varies seasonally and regionally. These variations may result in bottlenecks within sorting machines, thereby causing inconsistencies in the quality and quantity of recovered material. While most recovery facilities attempt to mix different bales before feeding them into the sorting line, relying on trial and error based on the material compositions of those bales, there is a lack of a systematic approach to this process. This paper introduces a systematic approach to plastic sorting within a plastic recovery facility, where the entire recovery process flow is dynamically modelled and validated. By identifying bottleneck regions within the system, infeed bales can be premixed to achieve the designed proportions, ensuring that machines and process lines are optimised for maximum efficiency. A pre-waste survey is necessary to achieve premixing, and the cost is justified by the benefits of the final return. To enhance the efficiency, it is crucial to implement a dynamic mixing model adaptable to daily variations in infeed. In this study, the dynamic optimisation model is designed in the form of simple mixing charts, allowing for on-site premix adjustments to bales without the need for additional equipment or tools. The proposed design chart based mixing methodology can be adopted across the globe to increase the output of established plastic recovery facilities.

The export ban on plastic waste by China has brought domestic plastic recycling to the forefront of environmental concerns, with sorting being a crucial step in the recycling process. This study assessed the performance of advanced AI models, Mask R-CNN, and YOLO v8, in enhancing plastic waste sorting. The models were evaluated in terms of accuracy, mean average precision (mAP), precision, recall, F1 score, and inference time, with hyperparameter tuning performed through grid search. Mask R-CNN, with an accuracy of 0.912 and mAP of 0.911, outperformed YOLO v8 in tasks requiring detailed segmentation, despite a longer inference time of 200-350 ms. Conversely, YOLO v8, with an accuracy of 0.867 and mAP of 0.922, excelled in real-time applications owing to its shorter inference time of 80-160 ms. This study underscores the importance of selecting the appropriate model based on specific application requirements.

Aerobic composting is an environmentally friendly and effective approach to treating organic solid waste. The variability in material composition introduces complex interactions between environmental factors and materials, which in turn affects compost maturity. This study uses multiple statistical analyses to systematically compare key indicators across composting processes for kitchen waste, livestock manure, and sludge. The results show that material type and composting stage have a significant impact on compost maturity (p < 0.001). High-precision modeling (R² > 0.90) was achieved using a Stacking model on the composting dataset, with interpretability analysis highlighting the important roles of temperature, moisture content, and nitrogen content across different composting materials. The combined effects of environmental and material changes jointly influence the composting progression. In kitchen waste composting, strong interactions between multiple indicators were observed, while moisture shifts in livestock manure and sludge composting primarily influenced compost maturity by promoting decomposition and enhancing nitrogen retention, respectively. Partial dependence analysis quantified the relationships between key indicators and compost maturity scores. These findings offer a scientific basis for identifying key factors and optimization paths in various composting processes, supporting the development of more effective composting strategies.

Post-consumer waste management systems have proven insufficient to meet the growing global demand. In this context, adopting alternative pathways that complement established practices, such as chemical recycling, becomes essential. Accordingly, this study evaluated the potential of the co-pyrolysis process to manage polyethylene terephthalate (PET) residues and waste cooking oil (WCO), converting them into industrial inputs. Three mixing ratios between PET and WCO were evaluated, assessing their synergistic effects through kinetic studies and comprehensive characterization of the final liquid product. The interaction between PET and WCO in the evaluated mixtures reduced the activation energy of thermal degradation by ∼ 40 % compared to raw PET, improving the energy viability of the process. The addition of WCO to the thermal conversion of PET favored the cracking of the polymer, thus the yield of the pyrolytic liquid increased from 44.41 % by weight to 59.38 % in the PW (2:1) mixture, 71.06 % in PW (1:1) and 79.86 % in PW (1:2). The synergistic interaction between the feedstocks led to an increase in terephthalic acid (TPA) production compared to the individual pyrolysis of PET. When PET and WCO were mixed in proportions of 2:1, 1:1, and 1:2, TPA production increased by 167 %, 73 % and 58 %, respectively. Moreover, the production of highly aromatic compounds was inhibited during co-pyrolysis, favoring the formation of less aromatic species. The results showed that the simultaneous management of wastes from co-pyrolysis offers advantages to the production process, presenting itself as a promising approach for the management and production of chemical inputs from PET and WCO.

The world's three leading tire manufacturers have proposed specific timelines for using recycled materials. For instance, Michelin targets an increase in the proportion of sustainable materials in tires to 40 % by 2030 and aims to produce 100 % of its tires from bio-based, renewable, or recyclable materials as of 2050. In such a context, this study introduced wet mixing technology to apply recycled rubber (RR) in highly wear-resistant tire tread compounds. This technique leverages the rubber's inherent crosslink density to enhance the mechanical performance of final products. The results indicated that wet mixing effectively addressed the high viscosity issue of RR. In the traditional dry mixing method, physical blending typically results in large particle sizes and suboptimal performance. In contrast, wet mixing reduced the rubber's hysteresis loss by 75 % and improved its rebound performance by 35.6 % at 23 °C, 60 °C, and 100 °C compared to traditional dry mixing. DIN volume abrasion was also reduced by 23.3 %. Remarkably, Akron abrasion nearly doubled its effect. Additionally, wet mixing regulated aggregate structure and formed a densely packed honeycomb-like structure within RR. Incorporating RR using wet mixing demonstrates noticeable advantages in carbon black/natural rubber/RR composite materials. This approach also presents a viable path to sustainable development in the rubber manufacturing industry.

Significant advances in the electrical and electronic industries have increased the use of electrical and electronic equipment and its environmental emissions. The e-waste landfill disposal has deleterious consequences on human health and environmental sustainability, either directly or indirectly. E-waste containing ferrous and non-ferrous materials can harm the surrounding aquatic and terrestrial environments. Therefore, recycling e-waste and recovering metals from it before landfill disposal is an important part of environmental management. Although various chemical and physical processes are being used predominantly to recover metals from e-waste, the bioleaching process has gained popularity in recent years due to its eco-friendliness and cost-effectiveness. Direct contact between microbes and e-waste is crucial for continuous metal dissolution in the bio-leaching process. Biofilm formation is key for the continuous dissolution of metals from e-waste in contact bioleaching. Critical reviews on microbial activities and their interaction mechanisms on e-waste during metal bioleaching are scarce. Therefore, this review aims to explore the advantages and disadvantages of biofilm formation in contact bioleaching and the practical challenges in regulating them. In this review, sources of e-waste, available metallurgical methods, bioleaching process, and types of bioleaching microbes are summarized. In addition, the significance of biofilm formation in contact bioleaching and the role and correlation between EPS production, cyanide production, and quorum sensing in the biofilm are discussed for continuous metal dissolution. The review reveals that regulation of quorum sensing by exogenous and endogenous processes facilitates biofilm formation, leading to continuous metal dissolution in contact bioleaching.

Each year, a significant number of smartphones are retired, yet retained by consumers. These hibernating smartphones have the reuse potential for another lifecycle. Nonetheless, they often stay in storage for a long time and may ultimately face inadequate recovery. This study explores consumers' perceptions regarding the value of hibernating smartphones over time. It examines the influence of factors such as the duration of smartphone storage and monetary incentives on users' decision-making regarding the End-of-Hibernation (EoH). The findings demonstrate that, on average, participants perceive the value of a newly retired smartphone to be 28% higher than its market value. This perceived value increases to 83% after three years since the smartphone's retirement. Participants' tendency to keep a hibernating smartphone increases as the gap between the monetary incentive and their perceived value of the device increases. Conversely, the longer the smartphone stays in hibernation, the less inclined users are to keep it.

Pharmaceutical biowastes, rich in organic matter and high in moisture, are typical light industry byproducts with waste and renewable attributes. Thermochemical and biochemical conversion technologies transform these residues into value-added bioproducts, including biofuels, biofertilizers, and bio-carbon materials. Hydrothermal pretreatment effectively removes toxic substances and enhances feedstock for these processes. This review comprehensively examines its role in improving the formation of bioproducts from pharmaceutical biowastes, focusing on (i) upgrading and denitrogenating solid biofuels with better combustion performance; (ii) enhancing biodegradability and gaseous biofuel production via organic matter decomposition; (iii) enriching soluble carbon and nitrogen for liquid biofertilizer; (iv) eliminating antibiotic residues and reducing antibiotic resistance in solid biofertilizers; and (v) stabilizing carbon and nitrogen structures and optimizing pore characteristics for functionalized carbon materials. The review recommends a potential staged thermochemical approach to co-produce nitrogen-enriched liquid biofertilizers and porous carbon materials from pharmaceutical biowastes. Hydrothermal pretreatment emerges as a key technique for facilitating the migration and conversion of essential elements like carbon and nitrogen. This study reveals the potential of hydrothermal pretreatment to address the limitations of pharmaceutical biowastes and offers insights into their valorization.