Journal of Cleaner Production最新文献

Civilian electromagnetic wave (EMW) absorbers are urgently needed to solve the excessive electromagnetic (EM) radiation energy pollution. Biomass, such as wood and bamboo, has a wide range of sources, is porous, and is suitable for forming functional composites. However, the diverse composition and microstructure directly affect the EM and thermal properties of conversion composites, and the corresponding influencing mechanisms are unclear. Here, a series of iron-containing biochar-based composites (CFBs) were synthesized by in-situ pyrolysis of impregnated flattened bamboo sliced veneers with Fe(acac)₃ dimethylformamide (DMF) solutions. The components and microstructures were pre-regulated through moisture-heat coupling softening, flattening and slicing treatments. Excellent EMW absorption performance with a $\left|{RL}_{\min }\right|$ value as large as 33.03 dB was obtained for CFB-0.8 at a fixed thickness of 1.15 mm, along with the widest effective frequency bandwidth as large as 4.08 GHz. Besides, In addition, CFB-0.8 has stable Joule heating performance (0.9V, 79.7 °C), and its in-plane thermal conductivity is 31.4 times that of flattened bamboo (0.62 W m⁻¹ K⁻¹). These are attributed to the rich heterojunction interfaces, electromagnetic attenuation caused by structures (porous structure scattering, nanoscale effects), deep absorption mechanisms caused by defects (lattice defects, electric field concentration, non-uniform carbonization structures), and thermal conversion. This work provides theoretical and experimental data for developing EMW absorption materials and new ideas for the high-value utilization of biomass materials and the continuation of their carbon fixation life.

Sewage treatment plants (STPs) are identified as a significant pathway of microplastics (MPs) re-entry into the environment through effluent discharge, thereby emphasizing the need for reliable and efficient treatment methods. This study investigated MPs removal from sewage effluents using cetyl trimethyl ammonium bromide (CTAB)-modified magnetic biochar (RH-MBC-CTAB) as an adsorbent. Biochars from different biomass were synthesized, surface modified, characterized, and compared for their MPs removal efficacy from aqueous matrices. Batch adsorption studies were initially conducted on synthetic water with 1 μm sized polystyrene (PS) MPs using different MP concentrations (1–10 mg/L) and varying adsorbent dosages (1–10 mg/50 mL) to assess the effect of different process parameters, viz. pH (2–10), humic acid (6–25 mg/L), and competitive ions (0.01–0.2 M). The maximum MPs removal (98%) was achieved at the favorable conditions: initial MPs concentration: 10 mg/L, RH-MBC-CTAB dose: 7 mg/50 mL, pH 4, mixing speed: 180 rpm, and contact time: 3 min. Electrostatic attraction and hydrogen bonding were likely to remove MPs while the MPs adsorption was best fitted by the pseudo-second-order kinetics model (R² = 0.91) and Langmuir isotherm model (R² = 0.94) with the maximum adsorption capacity of 247.52 mg/g. Further, the application of RH-MBC-CTAB on the real-time sewage effluents from sequencing batch reactor (SBR) and moving bed biofilm reactor (MBBR)-based STPs spiked with MPs showed up to 96% MPs removal. The reusability results revealed that developed RH-MBC-CTAB could maintain good stability for up to three reusability cycles, therefore offering extensive potential for the removal of MPs from sewage effluents.

One challenge that product design has faced is the ongoing threat of obsolescence, where investment in an updated solution can quickly become irrelevant within months or years as technology advances. This phenomenon not only affects consumers, who may find themselves with quickly outdated devices but also poses a dilemma for designers and manufacturers who must balance constant innovation with sustainability and product durability. In this dynamic scenario, there arises a critical need to understand how design attributes impact obsolescence and how this relationship can influence the creation of more sustainable and resilient products. This paper develops a taxonomy of product design attributes influencing different types of obsolescence to address the research gap between product design and obsolescence. It investigates the significance of obsolescence types across product categories, the impact of design attributes on these obsolescences, and the role of design in product sustainability. Employing a theoretical framework combining product design and lifecycle analysis, the methodology includes a literature review and an expert survey to evaluate design attributes against obsolescence types. From the literature review, 21 design attributes were identified and evaluated by 26 industry and academia experts. The findings reveal distinct patterns of obsolescence in various product categories, emphasizing the influence of specific design attributes. The role of attributes such as upgradeability and compatibility in technological, functional, and planned obsolescence was highlighted. Limited familiarity with certain types of obsolescence among experts was acknowledged, underscoring the importance of raising awareness within the design community. These insights are critical to align product design with sustainability goals and challenging traditional product development practices. The study has significant implications for designers, manufacturers, and policymakers, highlighting the importance of understanding design choices in reducing obsolescence and promoting sustainable consumption.

Anaerobic fermentation is frequently hampered by toxicity arising from oxidative stress, and antioxidant enzymes play a crucial role in combating oxidative stress. In this study, the mechanism of microbial consortium and metabolic pathways regulated by antioxidant enzyme genes in anaerobic fermentation with different pH values was revealed. The results showed that antioxidant enzyme genes, such as glutathione peroxidase, peroxidase, and superoxide dismutase, were 5 times, 3 times, and 2 times higher at pH 7 than at pH 5, respectively. This allowed Clostridium to effectively resist oxidative stress, with substrate metabolism dominated by glycolysis, leading to an increase in the NADH/NAD⁺ ratio. Furthermore, the relative abundance of hydrogenase and electron transfer efficiency increased by 4.5 times and 2.71 times, respectively, resulting in a hydrogen production of 21.48 L/L. When antioxidant enzyme genes were inhibited at pH 5, the substrate mainly produced biomolecules for combating oxidative stress through the pentose phosphate and glycerophospholipid pathways, and led to the transformation of dominant genus into Lactobacillus. With an increased lactate dehydrogenase activity of 5.34 times, the final lactate production reached 65.17 g/L, which was 19.69 times higher than at pH 7. These results elucidate the regulatory mechanism of pH mediated antioxidant enzyme genes on hydrogen production and improve the controllability of anaerobic fermentation.

Lignin-based biopolymer-bound soil composites (BSCs) are a new class of sustainable construction materials that utilize a bio-based biopolymer — lignin — as a binder. Prior use of lignin suggests that lignin is a promising candidate for the development of bio-based construction materials. Inspired by these applications, lignin-based BSCs were developed using lignoboost lignin, lignoforce lignin, alkali lignin, and hydrolysis lignin. Uni-axial compressive testing of lignin-based BSC shows that the compressive strength for these BSCs range from 1.6–8.1 MPa, which makes them appropriate for low compressive strength construction applications. We performed a life cycle assessment (LCA) of lignin-based BSC, with the functional unit being a CMU-sized block ($V=6423c{m}^3$). The major advantage of BSC lies in the elimination of ordinary portland cement, which is common to many construction materials, including many forms of concrete. Furthermore, the use of lignin in lignin-based BSC results in carbon sequestration (lignin $\approx$ 60 wt% carbon), potentially making construction materials made from lignin-based BSC carbon negative. Additionally, a design guide for estimating the life cycle carbon footprint of lignin-based BSC for a required compressive strength was developed. By utilizing the results from material tests and the LCA, designers are now able to use lignin effectively in construction applications, as they can now design lignin-based BSC for a target compressive strength with a full understanding of the life cycle carbon footprint implications.

Metal pollutants have become increasingly diverse. Therefore, managing the ecological risks associated with these elements in soil is urgently required. However, determining the soil ecological risk thresholds of elements through routine toxicological tests is time-consuming and laborious, establishing prediction models is vital to risk management. Accordingly, this study aimed to predict the element toxicity to soil organisms by collecting the toxicological data of eight elements to soil organisms at 18 European and 17 Chinese sites through literature and toxicology databases, using the quantitative ion character-activity relationship (s-QICAR) model. Firstly, the toxicity values (logEC₁₀) of eight elements to five biological species and three microbial processes were obtained through clustering and soil normalization methods in three typical soil scenarios. Correlation analysis revealed that for different species and microbial processes, there are three to six physicochemical properties of elements related to their toxicity, among which, the covalent radius of the element was the best significantly correlated with logEC₁₀ of all organisms (R² = 0.77–0.95). Based on this, the s-QICAR model was established and used to predict the logEC₁₀ of Sc, Ti, V, Cr, Co, Ni, Cu, and Zn to eight organisms. Furthermore, along with the species sensitivity distribution curve, the HC₅ values (i.e., 95% species protection level) for the above eight elements were calculated. Following correction, the predicted no-effect concentrations of these elements ranging from 9 to 189 mg/kg, and the ecological risk threshold map has been produced. In summary, we present a new method to quantify the ecological risk of metal-induced pollution in European soils without routine toxic measurements, and provide important insights into soil pollution risk assessment and management.

Habitat degradation is one of the most serious environmental problems worldwide, which threatens human wellbeing and sustainable development. Exploring how to protect natural habitats has become a research hotspot in the environmental management field. Ecological zoning has been widely used in habitat protection, but its actual effectiveness has been rarely revealed, especially with the robust and reliable causal inference method. Therefore, taking the Yangtze River Economic Belt (YREB) in China as the study area, we first quantified habitat quality and changes at the district/county scale during 2005–2019. Then, we used the National Key Ecological Function Zone (NKEFZ) as a representative ecological zone scheme, and explored the effectiveness of the NKEFZ in protecting habitat quality with the Propensity Score Matching and Difference-in-Difference combined method, which is a representative causal inference method. We found that habitat quality showed an uneven distribution during the study period, and habitat quality of districts/counties within the NKEFZ was higher than that outside the NKEFZ with statistical significance. Most districts/counties experienced a habitat quality decrease, but the decrease within the NKEFZ is less than that outside the NKEFZ. We observed that the NKEFZ can protect habitat quality from the causal relationship perspective, but there was the spatio-temporal heterogeneity of the NKEFZ effectiveness. In terms of the spatial dimension, the NKEFZ was the most effective in the Lower Reach of the YREB. In terms of the temporal dimension, there was a 1-year time-lag effect of the NKEFZ effectiveness, and NKEFZ effectiveness experienced a sharp increase from 2016. The NKEFZ contributed to protecting habitat quality through multiple management strategies such as urban land quota, high pollution industry prohibition, and ecological compensation. Overall, this study verified that the ecological zone scheme can contribute to habitat quality protection, and emphasizes that the effectiveness of ecological zoning may vary across time and space. This work can support ecological zoning implementation with robust evidence, and provides a novel perspective for understanding the effectiveness of ecological zoning.

Background

Healthcare represents 3–8% of a country's carbon footprint, and medicines are estimated to represent 20–55% of healthcare's carbon footprint. Unfortunately, only scarce and partial medicine life cycle assessments (LCAs) are reported due to the limited availability of needed data to perform them.

Methods

We describe a method to estimate the cradle-to-pharmacy gate LCA of all oral medicines from the French pharmacopeia (n = 12,316 medicines) that includes the entire medicine-related carbon footprint, encompassing active pharmaceutical ingredient (API), excipients and packaging production, transport, medicine manufacturing, and associated corporate emissions using a hybrid LCA/environmentally extended input-output model. The uncertainty surrounding this estimation is modeled using bootstrap.

Findings

Although the API carbon footprint is correlated with synthesis yield, its number of steps, presence of chiral center(s), and process mass intensity, the API carbon footprint is better predicted by its wholesale cost. Corporate emissions (34.5%), API production (28.5%), and medicine manufacturing (25.5%) are the most impactful contributors to medicine carbon footprints, while medicine packaging (5.3%), transport (3.6%), and excipients (2.7%) are less significant. Variations from one medicine to another are substantial. The mean carbon footprint of a medicine box is 8.47 kgCO2eq/box (median 1.46 kgCO₂eq, 95% CI 0.34–73.98). Medicines' carbon footprint is correlated with their price but not linearly, as low-cost medicines have significantly higher emission factors of 0.2–0.3 kgCO₂/€ versus 0.05–0.1 kgCO₂/€ for high-cost drugs. Orphan and innovative medicines tend to have higher carbon footprints.

Interpretation

Medicine carbon footprints are highly variable. This database allows for a better understanding of the carbon footprint associated with medicines, in order to better eco-design care pathways.

Circular economies have become a strong candidate for addressing environmental challenges by managing end-of-life products to reduce landfill waste. We herewith focus on the recycling of PET from plastic waste and textiles. This paper focuses on recycling PET from plastic waste and textiles and proposes a model for controlling plant operations, emphasizing Quality-Based Changeovers over cleaning to ensure production continuity. This paper also identifies technological and managerial challenges in PET recycling plants as raised in the related literature, such as the need for technology improvement, more effective collection routes and sorting processes, and devoted managerial strategies. Since a relevant industrial need is to manage the changeovers, we develop a model to control the operative management of the plant and to find the feedstock quality to be processed at a given time for profit maximization. A discrete event simulation model is built to represent the behavior of the system under an approximate state-based control policy, i.e. a two-threshold policy. Numerical results and sensitivity analysis highlight the impact of cleaning costs on system behavior, offering insights into optimal operational conditions.

Despite the increasing economic benefits generated by the cluster effect of the automotive industry, CO₂ emissions have become a serious challenge in the “3060” dual-carbon context. There are significant uncertainties regarding the impact of automotive industry agglomeration on urban CO₂ emissions, including quantifying impact thresholds and understanding the sensitivity of different agglomeration patterns. This study explores how automotive industry agglomeration impacts CO₂ emissions across 278 Chinese cities, and uncover the impact patterns based on varying city characteristics. The results show that the technology agglomeration of the automobile industry exhibits a nonlinear “U-shaped” impact on CO₂ emissions with a threshold value of 0.4267, while the scale agglomeration shows a nonlinear inverted “U-shaped” impact with a threshold value of 0.1206. In low-carbon demonstration cities, technology agglomeration has the most significant impact, with fluctuations ranging from −14.65% to 16.12%. In contrast, transitional cities are most affected by scale agglomeration, with a fluctuation range of −18.1%–11.19%. Besides, the results indicate that China's automobile industry development programs tend to relocate economic activities from highly agglomerated low-carbon demonstration cities to potential development cities with lower levels of agglomeration and other transitioning cities. Lastly, the results reconfirm that developing automotive industry development models based on cities' characteristics can enhance the environmental benefits of industrial agglomeration.