查看更多>>摘要：In Japan, the material recycling (MR) of plastic packaging waste faces several problems. Almost half of the collected waste plastics become residue, and the quality of recycled resins is not high because the mixture of various types of plastics makes sorting by resin type difficult. Therefore, an appropriate combination of source separation targets and sorting processes based on plastic type needs to be explored to increase the quantity of waste plastics recycled and enhance the quality of recovered plastics. Furthermore, the acceptability of recovered plastics as raw materials for use in plastic products needs to be assessed by matching the quantity and quality of recovered plastics with the demand and quality requirements of resin users. In this study, we evaluated the purity and quantity of plastics recovered by resin type for 80 combinations of source-separation targets and sorting processes based on the results of a sorting experiment using an actual optical sorter. Then, we developed recycling scenarios that optimized the quantity and/or quality of plastics recovered for MR by allocating waste plastics to the 80 source-separation/sorting schemes using linear programming with the upper limit of the acceptable amounts of recovered plastics and quality constraints. We found that the recycling target established by the Japanese government could be reached, if resin users proactively accepted recycled resin. On the other hand, the current rate of MR could be maintained solely with high-quality recovered plastics, if the collection rate for recycling and the acceptable amounts of the high-quality recovered plastics were significantly boosted.
查看更多>>摘要：Food production is responsible for approximately 17% of Germany's greenhouse gas (GHG) emissions. After retail, out-of-home catering is the second largest food sales channel in Germany. A variety of means on both the supply and demand side are necessary to stimulate, facilitate and encourage a more sustainable development and minimise GHG emissions in this sector. Nudges are one of these. This paper's focus lies on the demand side. Set in real-world laboratories, we use a standardised empirical approach to compare different nudging interventions belonging to the area of physical environment and consumers' choice making process. We compare the effects of the same intervention across different settings and the effect of different, sequential nudging interventions in the same setting. Data was collected in eight workplace and school cafeterias in Germany over two project iterations (2016/2017; 2019/2020). A similar intervention design was applied. Comparability was assured by a harmonised menu. The first project iteration revealed that only one nudge (top menu position, +22.5%) led to significant increases in sustainable food choices, while results from the second iteration showed that all nudge interventions (best counter position, +11.6%; top menu position, +6,9%; label plus information, +15.9%) positively influenced consumer choice. Possible explanations such as the stricter compliance to the experimental design in the cafeterias but also societal developments such as the appearance of the Fridays for Future movement are discussed. As results vary between specific locations and settings, our findings suggest that nudges need to be adjusted to situational conditions for achieving highest efficacy.
查看更多>>摘要：Demand for new buildings and infrastructure continues to grow and will only increase in coming years to cater for forecast growth in global population. This demand will result in considerable strain on the natural environment, resulting from the operation of these new built assets as well as the demand for resources required to construct and maintain them. Life cycle assessment is a tool that can be used during the design or refurbishment of new or existing buildings or infrastructure projects, to assess and improve their environmental performance. A life cycle assessment is often time consuming and complex, especially when used for the analysis of entire construction projects. This is particularly true when it is used to analyse construction-related, or embodied, environmental flows (e.g. embodied greenhouse gas emissions). To simplify the process, especially with projects that have tight time or budget constraints, product-based environmental flow coefficients are often used, which provide an indication of the environmental flows associated with specific construction materials. However, existing coefficients are typically based on process data, inherent with truncated product system boundaries. This paper introduces the Environmental Performance in Construction (EPiC) Database, a comprehensive database of hybrid embodied environmental flow coefficients for construction materials in Australia. EPiC uses a hybrid life cycle inventory approach to fill the gaps that exist in process data and provide embodied environmental flow coefficients that are systemically complete. This study has shown that existing process data for materials is on average 55% incomplete, but considerable inconsistency in system boundary coverage means that this incompleteness varies from 2% to 99% across materials and environmental flows. Other key strengths of EPiC are its transparency, providing open access to all data, and methodological consistency, with coefficient data sources and methods being the same for all materials. Environmental flow coefficients from EPiC can be used on their own or integrated into existing life cycle assessment tools, informing improvements to the environmental performance of construction projects.
查看更多>>摘要：Plastics are one of the most greenhouse gas (GHG) intensive and the fastest growing industries in the manufacturing sector. Environmental tradeoffs of plastics occur through all stages of their life cycles, accelerating climate breakdown and threatening our ability to maintain a sustainable climate. Herein, material flow analysis (MFA) of three major synthetic resins (PVC, PP, PE) in China was first conducted from production to end-of-life. Meanwhile, life cycle assessment (LCA) was applied to investigate "cradle-to-gate " environmental impacts of these synthetic resins, and then GHG emissions during each plastic life stage were quantified by the integrated LCA-MFA framework. Results suggested that GHG emissions during resin production were 5.42, 4.72 and 3.43 kg CO(2)eq for 1 kg PVC, PP and PE, respectively. Taken together, China generated 304 million metric tons (Mt) CO(2)eq in 2020 by synthetic resin production, and additional 44 and 55 Mt CO(2)eq were emitted due to further plastic product manufacturing and end-of-life management, respectively. Packaging was identified as the major GHG contributor during the use phase, which should be critically monitored for GHG management. The study provides a new perspective to reveal environmental hotspots that drive GHG emissions among plastic life cycles and guides policy-makers towards effective carbon control and sustainable plastic management.
查看更多>>摘要：The main purpose of this paper is to study the feasibility of producing concrete made of 100% recycled materials, by using coal fly ash (FA) or granulated blast-furnace slag (GGBS) activated by waste water coming from concrete production and with lime residue coming from the waste of a slaked lime factory as the binder, instead of conventional Portland cement binder. Conventional aggregates were replaced by various percentages of recycled concrete, crushed brick, recycled bottle glass and sediments. Used cooking oil was incorporated as an admixture to improve the fresh properties of the concretes. Several formulations of concrete were tested in order to evaluate their fresh and hardened properties. The results show that it is feasible to formulate concretes containing only recycled materials. The binder composed of GGBS and slaked lime could lead to quite high performance in the long term, especially when used with recycled concrete aggregates. The dry concretes obtained could reach compressive strengths of up to 37 MPa at 9.5 months. Attempts to improve the workability by the use of admixture (e.g. used oil) or less absorbent aggregates (e.g. waste glass) gave limited results and still need to be developed in order to limit the loss of strength. Before any generalization of the results, the variability of the wastes used should be taken into consideration.
查看更多>>摘要：Fire extinguishers are used to contain the imminent risk posed by fire globally. Suitable disposal and utilization of fire extinguisher powder (FEP) waste have developed into a significant challenge due to high nitrogen and phosphorus content. Harnessing the waste as a secondary resource for integrated waste-to-profit enterprises, such as microalgae cultivation for high-value bio-based products, is considered crucial for sustainable production, resource conservation, and mitigating adverse effects on environments. This paper proposes an algae-based circular economy concept to recycle one of the most difficult to treat wastes globally by applying it as a nutrient resource for microalgae biomass production. Hydrophilizing the waste for nutrient release is critical to this valorization pathway due to its hydrophobicity. Ten solvents were tested, of which five, including ethanol/methanol-sodium hydroxide mixtures, acetate, isopropanol, and polysorbate-20, were effective in hydrophilizing the powder waste, without significant differences (p < 0.05) in nutrients release (80 - 120 mg N-NH4+ gFEP(-1)). Highest biomass productivity (102.7 +/- 3.98 mgL(-1)d(-1)), NH4+-N uptake efficiency (58%), and biomass yield on PO43--P utilized (12.6 g phosphorus g(-1) biomass) were obtained with the most robust microalgal strain (Chlorella sp. MUR269) in isopropanol-based FEP medium under mixotrophic conditions. The inherent low nitrogen to phosphorus ratio (N:P < 1) is prohibitive for bioremediation purposes, creating room to utilize the waste as a phosphorus source. Microalgae performance in culture media in which phosphorus was replaced with FEP was generally similar to the control media (p > 0.05), except for Chaetoceros muelleri, which had 70% more biomass in control than in the waste medium. The protein and carbohydrate contents of Chlorella biomass cultivated in the waste were not significantly different, though significantly higher than carbohydrate (p < 0.001). FEP waste can act as nitrogen and/or phosphorus fertilizers for algal cultivation without significant growth inhibition. The resulting biomass can be valorized to high-value products such as pigments and animal/aquaculture feed due to more than 50% protein content if it meets permissible regulatory levels of contaminants.
查看更多>>摘要：Municipal solid waste (MSW) properties and parameters for MSW treatment technologies are decisive for GHG emission of MSW treatment systems. But they are changing in China due to MSW source segregation and technological advancements, which requires new studies on GHG emissions of MSW treatment systems based on up-to-date data. In this study, GHG emission values and their uncertainties of waste treatment systems before and after MSW source segregation in Shanghai were analyzed utilizing Life Cycle Assessment (LCA) methods and Monte Carlo analysis. The results showed that before waste segregation, 21.0 similar to 319 kg CO2-eq GHG per tonne was emitted and that -139 similar to 203 kg CO2-eq GHG per tonne was emitted after waste source segregation. The source segregation helps to reduce GHG emissions from MSW treatment systems. In the long run, waste to energy incineration was not recommended from GHG perspective and anaerobic digestion has a great potential for GHG emission reductions.
查看更多>>摘要：The unsustainable use of irrigation water is one of the most serious environmental problems in coffee farming. Rapid expansion of sustainability certifications and adoption of advanced irrigation technologies are expected to promote more sustainable water use through changes in water management practices in coffee farming. However, there lacks empirical evidence on the effects of those certification schemes on water efficiency. This study examines the effect of sustainability certification on the water efficiency of coffee growers, considering distinct irrigation technologies used by farmers overhead sprinkler and micro-basin irrigation technologies. The meta frontier framework is used in our empirical analysis of 896 Vietnamese coffee farms over three crop years. Results confirm that irrigation water efficiency in coffee farming is substantially low. There is no evidence supporting the effect of sustainability certification on water efficiency, but advanced irrigation technologies could improve water efficiency. Coffee farms using the sprinkler system are more efficient than those using the micro-basin irrigation technology. Our results also support environmentally friendly farming practices, i.e., having wind-break trees on coffee farms. It also suggests that improving the quality of sustainability certification schemes towards sustainable use of water requires water-saving technologies.
Du, WenqianZheng, JiahuiLi, WenxiaLiu, Zhengdong...
11页
查看更多>>摘要：In order to better recycle waste textiles and save resources, intelligent identification and sorting equipment and technology are urgently needed. In this work, an online near infrared (NIR) spectral library was established by utilizing self-developed online NIR device, including polyester, cotton, wool, silk, viscose, nylon, acrylic, polyester/cotton, polyester/wool, polyester/nylon, polyester/viscose, nylon/spandex and silk/cotton. Importantly, artificial intelligence technology was introduced into the identification and sorting of waste textiles, and two online NIR qualitative identification models covering above 13 kinds of waste textiles were constructed by the convolutional neural network (CNN) and Baidu deep learning platform PaddlePaddle. First, the input onedimensional spectral data (901-2500 nm) was normalized and converted into a two-dimensional grayscale image of 40*40 pixels. Then feature extraction, compression and dimension reduction of multiple spectra were carried out through convolution and pooling. Finally, the category probability value of each kind of waste textiles was calculated by the CNN model and the maximum value was taken as the final classification of the fabric. Online identification tests were performed using 526 samples as an external validation set, presenting an accuracy of two CNN qualitative identification models were both more than 95.4%. In addition, the accuracy of online identification and sorting was above 95%, and the recognition and sorting time of each sample is less than 2 s, which can perform the efficient identification and automatic sorting of waste textiles.
NSTL
Elsevier