Additive manufacturing (AM) of composite materials is promising to create customizable products with enhanced properties, utilizing materials like carbon fibers (CFs). To increase their circularity, composite recycling has been proposed to re-introduce the recovered components in AM. A careful evaluation of recycling is necessary, considering the sustainability and functionality (i.e., mechanical properties) of the recovered components. Thus, Life Cycle Assessment (LCA) is applied to estimate the environmental impacts of AM via Fused Filament Fabrication (FFF), using virgin or recycled CFs via solvolysis at a laboratory scale. This study aims to provide a detailed Life Cycle Inventory (LCI) of FFF and evaluate the sustainability of using recycled CFs in AM. For both virgin CF manufacturing and CF recycling, electricity consumption was the main contributor to environmental impacts. CF recovery via solvolysis resulted in lower impacts across most impact categories compared to AM with virgin CFs. Different scenarios were examined to account for the mechanical properties of recycled CFs. AM with 75% recycled CFs, compared to 100% virgin CFs undergoing landfilling, resulted in over 22% reduction in climate change potential, even after a 50% loss of recycled CF functionality. Overall, this study offers insights into the LCI of FFF and shows that CF recycling from composites is worth pursuing.

In the last few years, the materials research community has shown increased interest in Advanced Materials (AdMas) that are specifically designed to substitute the traditionally used materials, not only with a view to their sustainability, sourcing criticality, or scarcity, but also to maintaining or even enhancing their functionality and performance. The use of AdMas is particularly researched in sectors where the environmental impact of the traditional materials is substantial, in terms of waste production or resource consumption. Due to their novelty and potentially unpredictable impacts, and to add further value to their application, there is an increasing interest in the safety and sustainability of AdMas. In this context, a new 5-step Safe-and-Sustainable-by-Design (SSbD) framework was developed by the European Union, to support the (re-)design and development of novel materials. A guideline is presented for enforcing the (re-)design phase of the framework with paradigms to guide stakeholders and practically add value to the materials’ industry. The present manuscript analyzes the advances and challenges of the SSbD framework, showcasing its applicability and limitations and the added value compared to traditionally used assessment methodologies, to provide a comprehensive evaluation of the methodology and add value to the materials’ industry concerning safety and sustainability.

Seagrass species have been recommended as biomonitors of environmental condition and as tools for phytoremediation, due to their ability to concentrate anthropogenic chemicals. This study aims to provide novel information on metal accumulation in seagrasses under laboratory conditions to support their use as a tool in the evaluation and abatement of contamination in the field. We investigated the kinetics of cadmium uptake into adult leaf blades, leaf sheaths, rhizomes and roots of Cymodocea nodosa in exposure concentrations within the range of cadmium levels in industrial wastewater (0.5–40 mg L−1). A Michaelis–Menten-type equation satisfactorily described cadmium accumulation kinetics in seagrass parts, particularly at 0.5–5 or 10 mg L−1. However, an S equation best described the uptake kinetics in rhizomes at 5 mg L−1 and roots at 10 and 20 mg L−1. Equilibrium concentration and uptake rate tended to increase with the exposure concentration, indicating that seagrass displays a remarkable accumulation capacity of cadmium and reflect high cadmium levels in the surrounding medium. Concerning leaf blades and rhizomes, the bioconcentration factor at equilibrium (range 73.3–404.3 and 14.3–86.3, respectively) was generally lower at higher exposure concentrations, indicating a gradual reduction of available binding sites. Leaf blades and roots accumulated more cadmium with higher rate than sheaths and rhizomes. Uptake kinetics in leaf blades displayed a better fit to the Michaelis–Menten-type equation than those in the remaining plant parts, particularly at 0.5–10 mg L−1. A marked variation in tissue concentrations mainly after the steady state was observed at 20 and 40 mg L−1, indicative of the stress induced on seagrass cells. The maximum concentrations observed in seagrass parts at 5 and 10 mg L−1 were comparatively higher than those previously reported for other seagrasses incubated to similar exposure concentrations. Cymodocea nodosa displays a remarkable cadmium accumulation capacity and reflects high cadmium levels in the surrounding medium. Kinetic models satisfactorily describe cadmium uptake in seagrass parts, primarily in adult leaf blades, at high exposure concentrations, permitting to predict cadmium accumulation in field situations. Cymodocea nodosa appeared to be a valuable tool in the evaluation and abatement of cadmium contamination in coastal areas.

In microbial electrosynthesis (MES), microorganisms grow on a cathode electrode as a biofilm, or in the catholyte as planktonic biomass, and utilize CO₂ for their growth and metabolism. Modification of the cathode with metals can improve MES performance, due to their catalytic activity for H₂ production, which can be consumed by microorganisms, or via modifying the cathode properties. On the other hand, metals can have an inhibiting effect on MES. While these single roles of metals and their oxides have been identified, an investigation of the simultaneous effects on MES is still lacking. Here, we modify activated carbon (AC) electrodes with nickel (Ni) at high (5%) and low (0.01%) loadings, to investigate its combined effects on MES. Upon Ni impregnation, multiple factors explained the MES performance, including electrocatalytic H₂ production, trace element availability, metal toxicity, Ni leaching and redeposition/bio-crystalization. Instead, the electrode surface properties (i.e., surface area and pore structure) were not affected by Ni addition. Compared to unmodified AC, low Ni loading did not improve abiotic H₂ production, whereas at high Ni loading a 6-fold increase was observed. During biological experiments, low Ni loading resulted in over a 3-fold increase of acetate production and 35% higher planktonic growth, compared to unmodified AC. Instead, high Ni loading resulted in 25-fold increase of acetate production, 21% decrease of planktonic growth, and improved biofilm growth. Unmodified AC, and low and high Ni loading each resulted in unique microbial community composition. The effect of Ni on MES is therefore concentration-dependent, with apparently different mechanisms of interaction being prevalent at low or high Ni loadings.

With the green energy transition, the wind industry has grown rapidly in recent decades. Wind turbine blades (WTBs) are primarily manufactured from glass fibers and thermoset matrix composites. Considering their lifetime from 20 to 25 years, significant amounts of wind turbine components will eventually enter the global waste stream. Currently, recycling is not sufficiently optimized and commercially available. Other strategies, such as repurpose, are becoming relevant to divert components from waste streams. This research explores a pathway to sustainable repurposing of decommissioned WTBs. The concept of a tiny house constructed from the root section of a 5 MW/61.5 m WTB is presented (“5 MW house”). The deformations and stresses of the repurposed composite structures were investigated using a finite element analysis based on the three load cases, defined by (1) a combination of snow load and payload, (2) a combination of wind load and payload, and (3) a thermal stress analysis of a critical temperature distribution of the 5 MW house. Furthermore, a life cycle assessment (LCA) was conducted to evaluate the environmental impacts of the proposed concept. The numerical analysis results showed that the 5 MW house can withstand the applied loads, and that the deformations are within acceptable limits. A reduction of up to 97% in environmental impacts for most impact categories was calculated, compared to a wooden tiny house, whereas climate change, ozone depletion, and eutrophication potential were up to 3.7 times higher, mainly due to the weight and composition of the 5 MW house. The authors believe that the proposed concept may be a high-volume repurposed solution for large-scale WTB root sections.