circular economy

Microbial technologies constitute a huge and unique potential for confronting major humanitarian and biosphere challenges, especially in the realms of sustainability and providing basic goods and services where they are needed and particularly in low-resource settings. These technologies are evolving rapidly. Powerful approaches are being developed to create novel products, processes, and circular economies, including new prophylactics and therapies in healthcare, bioelectric systems, and whole-cell understanding of metabolism that provides novel insights into mechanisms and how they can be utilised for applications...

Approximately 10 % of global anthropogenic CO2 emissions arise from the cement and concrete industry driven by urban expansion and a constant need for infrastructure renewal. Reusing waste CO2 to make new construction materials produces circular carbon flows and constitutes a key step toward a carbon-negative economy. To establish a holistic view of the field, this paper examines upscaled technologies with industrial deployments for utilizing CO2 in manufacturing cement-based materials and analyzes their interplay for attaining net-zero emissions (NZE) in the concrete sector...

Materials from green resources boast a low carbon footprint, forming the foundation of the circular economy approach in materials science. Thus, in this study, waste poly(ethylene terephthalate) (PET) was subjected to depolymerization using propylene glycol (PG), and subsequent polycondensation with bio-based maleic anhydride (MA) produced unsaturated polyester resin (b-UPR). Bio-derived acryloyl-modified Kraft lignin (Kf L-A) served as a vinyl reactive filler in the b-UPR matrix to create b-UPR/Kf L-A composites...

The rapid urbanization witnessed in developing countries in Asia and Africa has led to a substantial increase in municipal solid waste (MSW) generation. However, the corresponding disposal strategies, along with constraints in land resources and finances, compounded by unorganized public behaviour, have resulted in ineffective policy implementation and monitoring. This lack of systematic and targeted orientation, combined with blind mapping, has led to inefficient development in many areas. This review examines the key challenges of MSW management in developing countries in Asia and Africa from 2012 to 2022, drawing insights from 171 academic papers...

Circularity assessment and monitoring have become a core research topic in academic societies, as well as a basis for developing economic development measures. Despite the circular economy (CE) being a game-changer for the agro-food sector, little effort has been made to identify its level of circularity. In order to achieve the transition to a CE, stakeholders and industry professionals must be provided with appropriate indicators, tools and methods. Due to the complexity of CE measurement, it is necessary to devise indicators, methods and tools that are tailored to each industry...

A sudden increase in polyurethane (PU) production necessitates viable recycling methods for the waste generated. PU is one of the most important plastic materials with a wide range of applications; however, the stability of the urethane linkage is a major issue in chemical recycling. In this work, termination reactions of a model urethane molecule, namely methyl N-phenyl carbamate (MPCate), are investigated using G3MP2B3 composite quantum chemical method. Our main goal was to gain insights into the energetic profile of urethane bond termination and find an applicable chemical recycling method...

The development of sustainable materials from the valorization of waste is a good alternative to reducing the negative environmental impact of plastic packaging. The objectives of this study were to develop and characterize pectin-based composite films incorporated with cork or cork with either coffee grounds or walnut shells, as well as to test the films' genotoxicity, antioxidant properties, and biodegradation capacity in soil and seawater. The addition of cork, coffee grounds, or walnut shells modified the films' characteristics...

Economic and environmental concerns over the accumulation of end-of-life carbon fibre composite waste have led to increased attention to sustainable materials with low environmental impact. Over decades of research, vitrimers, a modern class of covalent adaptable networks, have bridged the gap between thermoplastics and thermosets. With the distinguishing feature of dynamic covalent bonds, vitrimers can be rearranged and reprocessed within their existing network structures in response to external stimuli such as heat or light...

The green walnut, which is frequently overlooked in favor of its more mature sibling, is becoming a topic of great significance because of its unique ecological role, culinary flexibility, and therapeutic richness. The investigation of the bioactive substances found in green walnuts and their possible effects on human health has therapeutic potential. Juglans regia L. is an important ecological component that affects soil health, biodiversity, and the overall ecological dynamic in habitats. Comprehending and recording these consequences are essential for environmental management and sustainable land-use strategies...

This study addressed the urgent need for sustainable protein sources in aquaculture due to the depletion of marine resources and rising costs. Animal protein sources, particularly poultry by-product meal (PBM) and insect exuviae meal, were investigated as viable alternatives to fishmeal (FM). The research study confirmed the successful replacement of FM with a combination of PBM and insect exuviae meal (up to 50%) in the diet of European seabass without compromising growth, feed conversion, gut health, and liver fat content...

In the circular economy framework, hydrosols, by-products of the essential oil industry, are gaining attention for their potential in waste reduction and resource reuse. This study analyzed hydrosols from six edible flowers, investigating their chemical composition (VOC-Hyd) and antibacterial properties alongside volatile organic compounds of fresh flowers (VOC-Fs) and essential oils (EOs). Antirrhinum majus exhibited ketones as major VOC-Fs (62.6%) and VOC-Hyd (41.4%), while apocarotenoids dominated its EOs (68...

The aim of this study was the characterization and evaluation of applicability as a soil amendment of biochar derived from rose pruning waste at different pyrolysis temperatures (200-500 °C) and process durations (20-60 min). The biochar properties were compared to the raw material. The biochars produced at 300 °C for 40 and 60 min demonstrated the best fuel properties. These variants showed high energy gain rates (77.6 ± 1.5% and 74.8 ± 1.5%, respectively), energy densification ratios (1...

To address the growing global water demand, it is imperative to implement advanced treatment systems and sustainable alternatives for managing the large amount of waste generated during the water purification process, known as water treatment sludge (WTS). Worldwide, researchers and companies are exploring alternatives and methods for the valorization of WTS as a raw material in other processes. It is urgent that all productive sectors, which contribute significantly to greenhouse gas emissions, adopt this management principle to ensure more sustainable production, contributing to the global goal of climate neutrality...

An innovative approach for the production of bio-micro/nanostructures with high-value compounds from agricultural by-products was studied. This research aimed to valorize bioactive compounds existing in the by-products of the plants of Fragaria vesca (wild strawberry). The particle characteristics, morphology, size, release properties, and antioxidant activity of micro/nanostructures containing the extract of by-products of the plants of Fragaria vesca or quercetin (one of the main polyphenols in the plant) were analyzed...

Coffee pulp is a by-product of the coffee industry. Due to conventional management techniques, it represents a severe environmental problem due to its negative impact on the soil (anaerobic fermentation and pH changes), water sources (the infiltration of pollutants into streams, acidification of water sources, and modification of microorganisms), and biodiversity (soil microbiology, fish, crustaceans, and other vertebrates). Therefore, it is essential to develop protocols for the treatment of this waste so that it can be used again in other productive activities under the circular economy approach...

Cellulose nanocrystals (CNCs) are cellulose-derived nanomaterials that can be easily obtained, e.g., from vegetable waste produced by circular economies. They show promising antimicrobial activity and an absence of side effects and toxicity. This study investigated the ability of CNCs to reduce microbial adherence and biofilm formation using in vitro microbiological models reproducing the oral environment. Microbial adherence by microbial strains of oral interest, Streptococcus mutans and Candida albicans, was evaluated on the surfaces of salivary pellicle-coated enamel disks in the presence of different aqueous solutions of CNCs...

The escalating threat of plastic pollution necessitates urgent and immediate action, particularly within the food and beverage (F&B) industry, a significant contributor to single-use plastic waste (SUP). As the global population surges, so does the consumption of single-use plastics in the F&B sector, perpetuating a linear economy model characterized by a 'take, make, use, dispose' approach. This model significantly exacerbates plastic waste issues, with projections indicating an alarming increase in plastic outputs by 2050 if current practices continue...

Approximately 75,000 tons of different sea urchin species are globally harvested for their edible gonads. Applying a circular economy approach, we have recently demonstrated that non-edible parts of the Mediterranean Sea urchin Paracentrotus lividus can be fully valorized into high-value products: antioxidant pigments (polyhydroxynaphthoquinones-PHNQs) and fibrillar collagen can be extracted to produce innovative biomaterials for biomedical applications. Can waste from other edible sea urchin species (e.g., Sphaerechinus granularis ) be similarly valorised? A comparative study on PHNQs and collagen extraction was conducted...

Shrimp processing generates substantial waste, which is rich in valuable components such as polysaccharides, proteins, carotenoids, and fatty acids. This review provides a comprehensive overview of the valorization of shrimp waste, mainly shrimp shells, focusing on extraction methods, bioactivities, and potential applications of these bioactive compounds. Various extraction techniques, including chemical extraction, microbial fermentation, enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, and pressurized techniques are discussed, highlighting their efficacy in isolating polysaccharides, proteins, carotenoids, and fatty acids from shrimp waste...

The enzymatic extraction of proteins from fish biomasses is being widely investigated. However, little or almost no research has paid attention to the exploitation of unsorted fishery biomasses. This work is part of a larger study, Part I of which has already been published, and focuses on an extensive characterization of two collagenous samples, namely gelatin (G) and hydrolyzed gelatin peptides (HGPs), extracted from a dehydrated fish biomass coming from unsorted canned yellowfin tuna side streams. The results indicate crude protein fractions of 90-93%, pH values between 3 and 5, white-yellow colors, collagen-like FTIR spectra, and 17% in terms of total amino acid content...