Circular economy and Industry 4.0 principles are increasingly shaping industrial practices. In the textile sector, environmental impacts and low recyclability make circularity a critical priority. This study focuses on enhancing both circularity and operational efficiency in a Portuguese manufacturer of labels and trimmings. Achieving this requires the collection of relevant data and identification of the factors that most influence operational performance, while linking these to circularity outcomes. To support this effort, the paper presents two complementary methodologies: Multi-layer Stream Mapping (MSM) for evaluating manufacturing efficiency and the Overall Circularity Index (OCI) for assessing circularity performance. MSM provides a detailed analysis of process efficiency, identifying sources of waste and summarizing results through user-friendly scorecards that highlight high-impact improvement areas. The OCI measures a company’s circularity on a scale from 0 to 1—where 1 represents full circularity—using strategic indicators across environmental, material, economic, and social dimensions. The MSM revealed an overall efficiency of 71%, whereas the OCI resulted in a final score of 0.516. When applied together, MSM and the OCI form a straightforward, iterative, and effective framework for diagnosing strengths and weaknesses in the manufacturing process, supporting evidence-based decision-making and guiding the company’s transition toward more circular and efficient operations.

The valorization of food waste through bioconversion using black soldier fly larvae (BSFL, Hermetia illucens) represents a promising pathway for sustainable waste management. However, the efficiency and safety of this process when using low-quality food waste substrates remain insufficiently characterized. This study investigated the adaptive responses, nutrient conversion efficiency, and product safety of BSFL reared solely on food waste (moisture 78.4%, crude protein 42.98%, pH 3.62) under controlled conditions (28 °C, 55% RH). Larval growth followed a logistic model (R2 = 0.96), with an inflection point at 13.14 days and a maximum daily weight gain of 0.0153 g/larva. Crude protein content increased significantly to 64.21%, while crude fat peaked at 26.42% by day 6 before declining. Larvae accumulated essential amino acids and functional fatty acids effectively. Notably, BSFL demonstrated a strong ability to exclude arsenic and chromium, with over 90% of these heavy metals retained in the frass. The frass itself exhibited high organic matter content (up to 61.57%) and an alkaline pH, meeting general standards for organic fertilizers. These findings underscore the resilience of BSFL and its potential for safe, high-value biomass production from challenging food waste streams, contributing to advanced circular economy strategies.

Valorization of municipal solid waste (MSW) for energy represents a strategic alternative for developing countries, as it mitigates emissions, reduces pressure on landfills, and diversifies the electricity matrix. This study quantified the potential for electricity generation from MSW in the Jequitinhonha Valley, Minas Gerais, Brazil, using primary gravimetric characterization data, a method rarely employed in tropical areas. The identified composition showed a predominance of the organic fraction (47.6–73.3%), confirming the relevance of biological routes. The results indicated a consolidated potential of 106,640 MWh·year−1, of which 94.7% was from biogas recovery and 5.3% from incineration. Almenara, one of the three locations analyzed, showed the highest potential (48,200 MWh·year−1), followed by Diamantina (34,540 MWh·year−1) and Capelinha (23,900 MWh·year−1). The specific yields ranged from 0.33 to 0.53 MWh·ton−1 MSW and the per capita indicators from 1.01 to 1.49 MWh·cap−1·year−1. The climate mitigation potential reached 1.0 Mt of CO2eq·year−1. It is concluded that valorization in the Jequitinhonha Valley should prioritize biogas recovery, complemented by the incineration of rejects. The materialization of this potential requires advancements in infrastructure, selective collection, and socio-productive inclusion. This study provides evidence for public policies and contributes to the literature by demonstrating that valorization can boost energy transition and socio-environmental equity in developing tropical regions.

Short-loop recycling of NdFeB trades a reduced ecological burden for a higher sensitivity towards contamination, as the powder is usually further processed as-is. In this investigation, the known effects of common contaminants (O, C, Ni, Cu, and Zn) introduced due to product design choices, namely from coating material and adhesive residue or a lack of corrosion protection, are reviewed. This study focuses on the impact of such contaminants on the magnetic properties and microstructure of recycled magnets via HPMS and re-sintering. Because of the lack of information regarding the practical effects of metallic coating residues, the impact of Ni contamination on the properties of re-sintered NdFeB magnets is assessed. HPMS processed scrap powder is blended with Ni powder and recycled by sintering. It is found that Ni partially substitutes Fe in the φ-phase, as expected from the literature review, leading to detrimental effects on the coercivity and remanence. The formation of an α-(Fe, Ni) phase is observed. The acceptable limit of Ni contamination without detrimental effects is found to be around 0.25 wt.%; however, due to the substitution in the φ-phase, the contamination is irreversible via short-loop recycling and would accumulate over multiple lifecycles.

The printed electronics sector is experiencing significant growth driven by societal expectations. The use of cellulosic substrates is an excellent strategy that offers interesting research prospects, but also sets challenges in terms of management and recycling of these new wastes to avoid their accumulation. This work investigates the recycling ability of paper-based printed electronics (a simple RFID antenna printed on paper), containing silver particles in the functional ink, using processes already applied in conventional paper and board recycling lines. These operations, commonly used in the papermaking industry, are pulping, screening, centrifugal cleaning, and flotation. The efficiency of each unit operation was evaluated. Mass balances between the inlet and the outlet of each studied operation have been established in order to evaluate the separation efficiency of Ag and cellulosic fibers, the objective being to reuse the fibers to manufacture a recycled paper, and to recover Ag in another fraction for further valorization. The results are encouraging, with more than 70% of silver and over 80% of cellulose fibers recovered, demonstrating a higher recovery efficiency compared to typical recycling methods reported in the literature. Thus, it has been shown that existing processes used in conventional recycling lines can be adapted to efficiently separate functional materials from cellulosic fibers, offering an improvement in both metal and fibers’ recovery.

A pilot-scale reactor prototype was designed to produce hydrocarbons through the catalytic pyrolysis process of low-density polyethylene, thereby extending its life cycle and contributing to energy efficiency and sustainability. The reactor consists of a stainless-steel tank encased in a ceramic jacket with refractory cement and clay bricks. The tank, made of 304 stainless steel, ensures mechanical strength and efficient heat transfer to the reactor core. A spiral condenser was incorporated into a water tank to cool the vapors and recover the liquid oil. The insulating materials, ceramic, refractory cement and clay brick, demonstrated a high combined thermal resistance of 0.159 m2·K/W. Simulations and energy flow calculations demonstrated that heat is efficiently directed to the reactor core, reaching 350 °C with only 3000–3800 W, while the outside of the jacket remained close to 32 °C. These results confirm that the proposed design improves thermal efficiency and optimizes energy use for catalytic pyrolysis. The novelty of this design lies in its energy-efficient configuration, which can be replicated in rural regions worldwide due to the accessibility of its construction materials. This reactor was developed based on a smaller-scale model that previously yielded excellent results.

This study developed sustainable foam-type composites from recycled paper (P), corrugated cardboard (C), and their 1:1 mixture (PC) for use in thermal and acoustic insulation. The materials were produced by water-assisted defibration, gas foaming with sodium bicarbonate and yeast, and oven curing, resulting in lightweight porous panels without synthetic binders. The composites exhibited distinct density and porosity profiles that influenced moisture behavior and stability. Cardboard-based panels absorbed the most water and swelled the most, while paper-based panels were more resistant. Despite these differences, all materials showed uniformly low thermal conductivity, confirming their strong insulation capability. Acoustic performance was enhanced by perforation and multilayer assembly. Cardboard panels with a triple-layer perforated design achieved the highest sound absorption, while mixed paper–cardboard composites provided balanced broadband performance. Microscopy revealed that fiber morphology—coarse in cardboard, fine in paper, and interlaced in mixtures—shaped the porous structure and bonding. Mechanical tests indicated comparable stiffness and strength across all types, with cardboard showing the strongest internal bonding. Overall, the results demonstrate that fiber structure and porosity govern material performance. These foam composites combine effective thermal insulation, competitive sound absorption, and sufficient mechanical strength, positioning them as biodegradable, low-cost alternatives for sustainable construction and acoustic applications.

This article focuses on the problem of processing slag waste from non-ferrous metallurgy, in particular, the loss of copper, gold and silver with slag during autogenous smelting in the Vanyukov furnace at the Balkhash Copper Smelter (BMZ). An analysis of factors affecting metal losses, including electrochemical and mechanical components, is presented. This paper offers a comprehensive study of the distribution of Cu, Pb, As, Au and Ag between matte and slag, taking into account the unique characteristics of the raw material and the technological conditions of the copper smelter, which distinguishes it from previous studies. This paper establishes numerical values of dissolved and mechanical losses of valuable metals. It has been established that the most important quantitative result of smelting polymetallic raw materials in a Vanyukov furnace is the proportion of mechanical copper losses in the slag, which is approximately 75–80% of the total copper content in the slag. Mathematical models are proposed to predict the distribution of metals in the process of smelting and loss of copper, gold and silver with slag. It is proposed to integrate model representations into the technology control loop, which will optimize the process of metal recovery. This will lead to an increase in profitability and a reduction in the negative impact on the environment during copper production.

The purpose of this study was to obtain a holistic view of mechanically recycled cotton from denim fabrics and the repurposing and recycling methods for similar fibres. A pre-consumer denim and three types of post-consumer denims were shredded into new fibres, which were characterised with single-fibre tensile testing, SEM imaging and DSC analysis. The opened cotton fibres were then blended with primary cotton with varying ratios and spun into yarns of 40 tex with a ring spinning machine. A ratio of 75/25 of recycled fibres to virgin fibres was obtained, with promising tensile strength results. Further, the yarns were knitted into single jersey fabrics, and abrasion testing was performed to evaluate their wearing out. Best abrasion resistance was obtained for knits consisting of 100% virgin cotton fibres and the knits consisting of a blend of pre-consumer and virgin fibres. The results suggest the yarns made with mechanically opened fibres are suitable for single jersey knits. SEM and DSC confirm the input of mechanical recycling defines the output. Moreover, the SEM pictures indicate there is little to no damage to single fibres caused by mechanical shredding, causing no further barriers for secondary use as raw materials.

To reduce energy consumption in buildings and to maintain comfortable conditions, lighting equipment that includes light-emitting diode (LED) lamps and lighting management equipment is utilised. In this study, integrated circuits detached from lighting equipment were characterised for the presence of precious metals (silver, gold, palladium, and platinum). Their digestion was carried out with HNO3 and aqua regia solution on a hot plate and characterised using inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of each element as a function of the type and origin of the integrated circuits varied as follows: silver, 652–3876 mg/kg; gold, 0–993 mg/kg; palladium, 0–74 mg/kg; and platinum was detected at a concentration below the quantification limit. These results indicate the need for selective removal and separate recycling processes for integrated circuits from the lighting equipment.