查看更多>>摘要：Consumer electronics contain a broad spectrum of materials whose production requires water and potentially discharges contaminants into the water supply, exacerbating freshwater scarcity and pollution. These water impacts have not yet been fully studied, as much of the literature on consumer electronics focuses on supply chain energy or carbon footprint. This study evaluates life cycle water consumption and degradation impacts associated with extracting and producing base, precious, hazardous, and critical metals that are typically found in electronic products. Water impacts were analyzed for individual metals and for the representative material profile of smartphones and laptop computers to identify "hotspots" for future improvement. Results indicate that, at the level of individual materials, precious metals have the highest impacts, due to water consumed directly for mining operations and indirectly for energy production, and water degradation attributed to metal emissions during mine tailings management. At the product level, precious metals also have the highest contribution per smartphone, whereas aluminum has a higher contribution per laptop, accounting for about 40% of the total water scarcity footprint. On the other hand, for water quality impacts, precious metals are responsible for the highest contributions for both products. Scenarios are evaluated to assess improvement potential associated with product design changes, including alternate supply chains, material substitution, and use of recycled content. The greatest potential opportunities for reducing water impacts were sourcing metals from lower water scarcity regions (19% reduction over the baseline water scarcity footprint) and increasing recycled content to the maximum theoretical potential (20% reduction).
查看更多>>摘要：In this study, preparation of hierarchically porous biochar (PB) and simultaneous nutrient recovery from sewage sludge were realized through three steps of KHCO3-activated pyrolysis, water leaching and acid leaching. The prepared PB samples were applied as adsorbents for the removal of 4-chlorophenol (4-CP) from aqueous solutions. Effect of pyrolysis temperature on the physicochemical properties of PB samples was investigated. The PB prepared at 900 degrees C (PB-900) had the highest surface area (1476.0 m(2)/g) and total pore volume (1.138 cm3/g). The formation mechanism of porous structure of PB-900 was revealed by investigating the phase transformation, element distribution and pore structure evolution during its whole preparation process. PB-900 showed a high 4CP adsorption rate of 14.4 mg/(g.min), and its maximum adsorption capacity for 4-CP was up to 192.4 mg/g. The mechanism of 4-CP removal by PB-900 was mainly physical adsorption, and its strong aromaticity strengthened its interaction with 4-CP through p- p bonding. The water leaching solution in the preparation process of PB-900 contained a lot of nutrient elements (K, Si, P), which was recovered for grass seeds germination. Compared with the samples cultured with ultrapure water only, the seed germination rate of samples cultured with ultrapure water added with 20% of pretreated water leaching solution increased from 63% to 80%, and the average shoot length of grass grown for 7 days increased by 51.4%. The findings of this study suggest that KHCO3 is an alternative activator to prepare hierarchically porous biochar adsorbent from sewage sludge and realize simultaneous nutrient recovery.
查看更多>>摘要：Controlling the hygrothermal conditions around fresh fruit and vegetables is vital for their preservation. Therefore, cold chain stakeholders often measure temperature along the supply chain of fresh produce. However, the temperature is typically monitored only in one segment of the entire cold chain, namely from the supplier until the distribution center. Besides, such measured data are rarely used for decision-making because they are not translated into the impact on the quality of the products. We provide a solution by extending the monitoring until the retail stores and upcycling these thermal data into actionable metrics. To do so, we use physics-based digital twins, namely virtual representations of the food products. This study focuses on 331 cold chain shipments of cucumber, eggplant, strawberry, and raspberry imported from Spain to Switzerland. We followed these fruits through pre-cooling, thermally stable conditions at the distribution center, and the temperature ramp-up phase before arriving at the retail store. The temperature performance of each carrier and flow analysis of the shipment enabled us to map the complex logistic system better. The digital twins detected that the fruits lost 43 - 85% of their quality before being displayed at the retail store. This quality loss remains invisible to the retailer. Additionally, we found a strong correlation between fruit quality and shipment duration (i.e., for cucumber r = -0.95 (P < 0.001)), which emphasizes the importance of shortening the shipment to prolong the freshness of the fruit. The digital twins have shown a large potential to help further maximize shelf life and uniform product quality.
查看更多>>摘要：Understanding the dynamics behind forest transitions, i.e., shifts from deforestation to forest recovery, is crucial for forest conservation and climate-change mitigation i.e., carbon (C) sequestration. We investigated the drivers of the forest transition in the United States, which was characterized by forest thickening despite surges in industrial wood extraction. We employ the concepts of Human Appropriation of Net Primary Productivity (HANPP) and Material and Energy Flow Analysis (MEFA) to quantitatively assess changes in major provisioning ecosystem services demanded from forests, i.e., industrial wood (comprising biomass used in products such as paper and pulp), grazing, and fuelwood, and analyse substitution processes from 1870-2012 at regional, sectoral, and national scales. The share of industrial wood in total annual forest biomass harvest increased from 23% to 84% over the time-period, while fuelwood and biomass grazed declined from 63% to 13%, and 14% to 3%, respectively. Reductions in demand for fuelwood and biomass grazed were enabled by shifts in feed and energy sources, consequently allowing for increases in both livestock numbers and energy use. Feed crops increased six-fold, alleviating grazing pressure on forest ecosystems, particularly in the Eastern states. Fossil fuels replaced fuelwood, especially in the residential sector. Between 1900-2012 the final energy mix increased seventeen-fold. Thus, the increase in biomass C stocks in U.S. forests was connected to substitution of forest ecosystem services with fossil fuel-based production systems, and with manifold increases in societal resource use and C dynamics. Such shifts need to be considered when assessing the positive environmental effects of forest transitions.
查看更多>>摘要：We use a combination of randomized field experiments and online surveys to test how the menu design affects food choices and food waste. In our field experiment, participants face one of two menus: a narrow menu that only displays a small portion of food, or a broad menu that also contains bigger portions. While all options are equally available in both menus, they differ in how easy and fast the different choices can be made. Our results show that, compared to the broad menu, participants in the narrow menu ordered smaller portions of food. Importantly, food intake was similar across conditions, leading to significant food waste reduction under the narrow menu. Our online survey experiments suggest that these results are consistent with a combination of anchoring and menu-dependent self-control theories. We discuss the implication of our results to menu design in real world settings.
Stefaniak, Aleksandr B.Bowers, Lauren N.Cottrell, GabeErdem, Ergin...
11页
查看更多>>摘要：Fused filament fabrication three-dimensional (FFF 3-D) printing is thought to be environmentally sustainable; however, significant amounts of waste can be generated from this technology. One way to improve its sustainability is via distributed recycling of plastics in homes, schools, and libraries to create feedstock filament for printing. Risks from exposures incurred during recycling and reuse of plastics has not been incorporated into life cycle assessments. This study characterized contaminant releases from virgin (unextruded) and recycled plastics from filament production through FFF 3-D printing. Waste polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) plastics were recycled to create filament; virgin PLA, ABS, high and low density polyethylenes, high impact polystyrene, and polypropylene pellets were also extruded into filament. The release of particles and chemicals into school classrooms was evaluated using standard industrial hygiene methodologies. All tasks released particles that contained hazardous metals (e.g., manganese) and with size capable of depositing in the gas exchange region of the lung, i.e., granulation of waste PLA and ABS (667 to 714 nm) and filament making (608 to 711 nm) and FFF 3-D printing (616 to 731 nm) with waste and virgin plastics. All tasks released vapors, including respiratory irritants and potential carcinogens (benzene and formaldehyde), mucus membrane irritants (acetone, xylenes, ethylbenzene, and methyl methacrylate), and asthmagens (styrene, multiple carbonyl compounds). These data are useful for incorporating risks of exposure to hazardous contaminants in future life cycle evaluations to demonstrate the sustainability and circular economy potential of FFF 3-D printing in distributed spaces.
查看更多>>摘要：Consumer food waste, like many environmental behaviours, takes place in private, and is not directly subject to social monitoring. Nevertheless, social interactions can affect private opinions and behaviours. This paper builds an agent-based model of interactions between consumers heterogeneous in their sociability, their initial opinions and behaviours related to food waste, and their willingness to consider different opinions, in order to assess how social interactions can affect private behaviours. Compared to existing models of opinion dynamics, we innovate by including a range of "cognitive dissonance" between stated opinions and actual behaviours that consumers are willing to accept before changing one of the two. We calibrate the model using questionnaire data on household food waste in Italy. We find that a limited degree of mixing between different socio-demographic groups, namely adult and young consumers, is enough to trigger change, but a certain openness of mind is required from more wasteful individuals. Equally, a small group of environmentally committed consumers can attract a sizeable share of the population towards low-waste behaviours if they show a certain variability of opinions and are willing to compromise with individuals in their close neighbourhood in terms of opinions. These findings can help design effective interventions to promote pro-environmental behaviours, taking advantage of the beneficial network effects while anticipating negative externalities.
查看更多>>摘要：Wind power is one of the fastest-growing energy in the world. Its contribution to global electricity generation should increase from 5 to 30% in 2050. With the increasing number of wind farms, we need to ensure that we will have enough material to meet the expected global capacity growth without creating new environmental issues. In this work, we estimated the material demand for wind turbines in the USA and the rest of the world and compared those values with the expected production until 2050. Based on the annual capacity installation, we quantified the carbon footprint and cumulative energy demand associated with the material production. Cement demand in 2032-2036 could be twice as much as the current amount used for wind turbines and pipeline construction in the USA. Compared to 2018, the USA steel demand in 2033 will increase by 511% (from 853 to 5215 kt). Rare earth elements (REEs) demand in the USA will increase by 254%-815% in 2033 (from 0.33 to 1.16-3 kt) compared to 2018. In the rest of the world, REEs demand will be 38% of the Chinese production in 2050. In 2050, the carbon footprint for materials required for wind turbines globally will be 9.3 times lower than the CO2 emitted currently from coal power plants in the USA. It is important to evaluate the potential impact of large-scale deployment of wind energy to avoid as much as possible creating new issues related to material scarcity, which could increase the carbon footprint of future electricity production.
查看更多>>摘要：Distiller's grains (DGS) as a typical organic solid waste in Chinese Baijiu production, with high water content, nutrient and various high-value components. Conventional waste management causes environmental issues and bioresource wasting. With the development of Chinese Baijiu companies, the demand for effective DGS treatment is urgent. There were various approaches for DGS resourcing, such as feeding, high-value components extraction, biogas production and composting. This review focus on the efficiency and existed limitations of these methods, includes the effects of feeds in livestock and poultry breeding, extraction efficiency and utilization, biogas yield and purity, and substance variation and stabilization in composting. As a prospect, process for DGS cascade and full utilization should be designed in further study. Combining and organizing the methods in different studies, decreasing the waste and discharge in process, optimizing the approaches in high value component extraction, promoting the utilization in different production, the value of DGS can be increased. The remained materials after cascade utilization can be further treated by full utilization in bioresource energy and composting. Therefore, Chinese Baijiu companies can achieve zero organic solid waste discharge and cleaner production.
查看更多>>摘要：Countries around the world are taking active efforts to address the current climate crisis. Negative emissions technologies (NET) such as enhanced weathering will play a significant role in these efforts in the coming decades. Enhanced weathering is based on the terrestrial application of powdered natural or synthetic silicate minerals to remove carbon dioxide (CO2) from the atmosphere. In the latter case, non-hazardous industrial waste (NHIW) can react with water and CO2 from the atmosphere to achieve carbon drawdown through the acceleration of the naturally occurring weathering process. This approach also addresses the problem of sustainable industrial waste management. Besides, carbon drawdown also enhances soil quality for agricultural application sites. In the future, planning the large-scale implementation of enhanced weathering via carbon management networks can be facilitated by using optimization models. In this work, a source-sink model is developed for the proper allocation of NHIW to application sites. The method is demonstrated with a case study based at Shandong Province, China. Two scenarios are analyzed, with both achieving significant negative CO2 emissions. The CO2 sequestration rates for these two scenarios are determined as 12.73 Mt/y and 13.77 Mt/y, respectively. Scenario 1 shows that the system can achieve negative CO2 emissions at a cost of $ 184.25/t CO2, which is comparable to previously reported cost estimates. Given the necessary input data, the model can be used to generate case-specific estimates for any country. The increasing use of clean energy in the transport and crushing process will enhance CO2 sequestration of the system.
NSTL
Elsevier