Search Results (195)

Composting represents a sustainable and effective strategy for converting organic waste into nutrient-rich soil amendments, providing a safer alternative to raw manure, which poses significant risks of soil, crop, and water contamination through pathogenic microorganisms. This study, conducted under semi-arid Moroccan conditions, investigated the efficiency of co-composting green garden waste with sheep manure in an open window system, with the objective of assessing pathogen inactivation and evaluating compost quality. The process, conducted over 120 days, maintained thermophilic temperatures exceeding 55 °C, effectively reducing key pathogens including Escherichia coli, total coliforms, Staphylococcus aureus, and sulfite-reducing Clostridia (SRC), while Salmonella was not detected throughout the composting period. Pathogen reductions exceeded 3.52-log despite moderate temperature fluctuations, indicating that additional sanitization mechanisms beyond heat contributed to inactivation. Compost quality, assessed using the CQI, classified Heap 2 (fallen leaves + sheep manure) as good quality (4.06) and Heap 1 (green waste + sheep manure) as moderate quality (2.47), corresponding to differences in microbial dynamics and compost stability. These findings demonstrate that open windrow co-composting is a practical, low-cost, and effective method for safe organic waste management. It supports sustainable agriculture by improving soil health, minimizing environmental and public health risks, and providing guidance for optimizing composting protocols to meet regulatory safety standards. Full article

The packaging sector is undergoing a significant transformation driven by increasing environmental challenges and new European regulatory frameworks. The Packaging and Packaging Waste Regulation (PPWR), following the European Green Deal and Circular Economy Action Plan, introduces five strategic priorities: waste prevention, recyclability, recycled content, compostable materials, and reusable systems. This framework aims to systematically review the current state of academic research in relation to these five intervention areas, assessing the extent to which the scientific literature supports the regulation’s circular economy objectives. The PPWR sets guidelines for key aspects such as packaging treatment, recycling targets, Extended Producer Responsibility (EPR) and material optimization. These aspects are strongly linked to market dynamics, driving innovation and new developments in packaging design. This study aims to provide a comprehensive overview of the industry’s evolution, with a focus on the crucial role of the circular economy in addressing the persistent issue of packaging waste. By conducting a systematic literature review using the PRISMA method, the research explores the relationship between the regulation’s structural design and the European Commission’s priority areas. The results reveal that waste prevention and reusability are the most researched areas, particularly concerning environmental assessments and regulatory tools like EPR. Additionally, while recyclability has been studied from technical and environmental perspectives, there is still a lack of research on how it connects with supply chain and material market trends. Strengthening these connections could significantly enhance recycling efficiency and improve the sustainability of packaging systems. Furthermore, financial incentives and policy strategies could play a key role in facilitating the transition to a circular economy. Addressing these gaps will foster a more integrated understanding of sustainable packaging solutions. Full article

The increasing challenges posed by climate change demand holistic approaches to mitigate ecosystem degradation. In Mediterranean-type regions—biodiversity hotspots facing intensified droughts, fires, and biological invasions—such strategies are particularly relevant. Among invasive species, Acacia longifolia produces substantial woody and leafy biomass when removed, offering an opportunity for reuse as soil-improving material after adequate processing. This study aimed to evaluate the potential of invasive A. longifolia Green-waste compost (Gwc) as a soil amendment to promote soil recovery and native plant establishment after fire. A field experiment was carried out in a Mediterranean ecosystem using Arbutus unedo, Pinus pinea, and Quercus suber planted in control and soils treated with Gwc. Rhizospheric soils were sampled one year after plantation, in Spring and Autumn, to assess physicochemical parameters and microbial community composition (using composite samples) through Next-Generation Sequencing. Our study showed that Gwc-treated soils exhibited higher moisture content and nutrient availability, which translated into improved plant growth and increased microbial richness and diversity when compared with control soils. Together, these results demonstrate that A. longifolia Gwc enhances soil quality, supports increased plant fitness, and promotes a more diverse microbiome, ultimately contributing to faster ecosystem recovery. Transforming invasive biomass into a valuable resource could offer a sustainable, win–win solution for ecological rehabilitation in fire-affected Mediterranean environments, enhancing soil and ecosystem functioning. Full article

The valorisation of household and commercial bio-waste into soil improvers helps to reduce disposable waste, mitigate climate change, and improve soil resilience. While the separate collection of bio-waste is mandatory in the European Union, this remains a challenging task, particularly for large cities, due to quality problems in densely populated areas. In addition to various informational and motivational tools for households, financial incentives are becoming increasingly important. However, there is a lack of robust evidence regarding the optimal use of these incentives and their impact on the quantity and quality of collected bio-waste. We investigated the impact of different charging systems on the quantity and quality of bio-waste, basing our research on the experiences of more than twenty European cities and using a detailed questionnaire completed by the relevant administrators. The results confirm that cities, which provide financial incentives for waste sorting, yield a higher quantity of separated bio-waste. As introducing tiered fees can lead to quality issues, monitoring bio-waste and taking action against polluters seems to be unavoidable. Since the identification of polluters is very difficult in the case of multi-family homes, the results are discussed with a special focus on densely populated cities. Pilot projects for alternative options for the valorisation of organic waste, particularly in districts with high-rise buildings, should be evaluated. Full article

(1) Background: The replacement of petroleum-based plastics with sustainable biopolymer films is crucial for global food preservation. Biopolymers like zein and pectin offer biodegradable and compostable alternatives but often require functionalization. This study develops and characterizes a novel antioxidant film by incorporating silver microparticles (AgMp) derived from the valorization of an agricultural waste product: pecan nutshell extract. (2) Methods: AgMp were synthesized via green reduction method using the extract. These bioactive microparticles were subsequently incorporated into a zein/pectin polymeric solution using the solvent-casting technique. The particles and the active films were characterized using FTIR, SEM, and antioxidant assays (ABTS, DPPH, and FRAP). (3) Results: The extract and AgMp exhibited a potent antioxidant activity (100% inhibition for ABTS/DPPH). SEM analysis confirmed the scale of 0.545–1.033 µm, classifying the material as microparticles. The final films retained a dose-dependent antioxidant activity (66.78% for ABTS and 53.67% for DPPH). (4) Conclusions: This work validates that pecan nutshell extract as an effective green reducing and capping agent. The resulting film possesses significant antioxidant activity, offering a promising alternative for active food packaging applications, such as bioactive pads or inserts. Full article

Humus is the core product and key indicator of compost maturity. How to improve the humus content and accelerate its formation in composting is critical for the improvement of compost quality. This study investigated the effects of adding compost derived from different stages including thermophilic, cooling, and maturation phases on compost initiation and efficiency in terms of humus formation and microbial community dynamics. The results reveal that adding compost from the cooling stage markedly outperforms the thermophilic and maturation phases, achieving a germination index of 107.22%, a carbon-to-nitrogen ratio of 15.95, a humus content of 91.12 g/kg, a humic acid concentration of 71.49 g/kg, and a polymerization degree of 3.64. EEMs indicated that the cooling-phase additive increased humic-like fluorescence (Region V) at day 35. The abundance and diversity of humifying bacteria were significantly enriched, and the succession of microbial community was accelerated as confirmed by redundancy analysis. This approach also improved compost quality and reduced the overall composting duration, thus suggesting that using compost from the cooling phase as an additive is an effective way to increase the humus content and accelerate the humification, providing a green solution for organic waste recycling and sustainable agricultural development and production. Full article

Island ecosystems, are characterized by isolation, limited land, and tourism-driven economies, face persistent waste management challenges. Spatial constraints and inadequate infrastructure often limit the development of waste recovery and recycling systems, leading to practices such as open dumping or burning that pose serious environmental and health risks. This paper examines how circular economy (CE) principles, reduce, reuse, recycle, can transform waste into a resource and enhance local resilience. A refined definition of “small islands” is introduced, combining UN criteria with a tourism-intensity filter to capture the strong link between visitor flows and solid waste generation. Barriers to CE adoption are classified into institutional, technical, geographical, financial, and social dimensions, and connected to enabling practices in four thematic areas: multi-stakeholder partnerships, recycling and composting innovations, policy and regulatory tools, and community engagement. Comparative case studies from Europe, Asia, Africa, and the Pacific reveal that integrated approaches are more durable than isolated efforts. Successful initiatives blend technology with governance, education, financial mechanisms, and community participation. The analysis highlights that no single model fits all islands; strategies must be locally adapted to be effective and transferable. Overall, the study shows that circular transitions are both feasible and necessary, offering environmental gains, economic value, and alignment with the EU Green Deal and global sustainability goals. Full article

A very important issue in urban agglomerations is the proper management of green waste while reducing its negative impact on the environment. One potential solution is the utilization of green biomass—originating from the maintenance of parks, squares, and home gardens—for the production of compost and compost-based pellets as organic fertilizers. The aim of this study was to produce compost-based pellets intended for fertilization purposes from compost derived from green waste and conifer sawdust, and to analyze their mechanical and chemical properties. Ten variants of pellets with different compost-to-sawdust ratios were evaluated. Compost-based pellets exhibited the highest initial mechanical strength; however, their resistance to external loads decreased over time, whereas the best long-term stability was observed in pellets containing 50% sawdust. The seasoning process influenced the stabilization or improvement of the mechanical properties of certain mixtures. Chemical analyses showed that compost-based pellets contained the highest concentrations of nutrients (N, P, K), while increasing the proportion of sawdust reduced their fertilizing value. No exceedances of permissible heavy metal limits were detected. The results confirm the suitability of compost-based pellets made from green biomass as a sustainable alternative to mineral fertilizers, supporting the principles of the circular economy. Full article

In response to growing pressures for sustainability in tourism, this paper examines the techno-economic evaluation of green innovations in small and medium-sized tourism enterprises (SMEs). Focusing on a single case study of a hotel in Greece, the research investigates how and why specific sustainability interventions were implemented and assesses their operational and economic impacts. The study adopts an interpretivist approach, combining process tracing with thematic analysis. The analysis is guided by innovation diffusion theory, supported by organizational learning perspectives, to explain the stepwise adoption of sustainability practices and the internal adaptation processes that enabled them. The techno-economic evaluation draws on quantitative indicators and qualitative assessments of perceived benefits and implementation challenges, offering a broader view of value beyond purely financial metrics. Data were collected through semi-structured interviews, on-site observations, and internal documentation. The findings reveal a gradual, non-linear path to innovation, shaped by adoption dynamics and organizational learning, reinforced by leadership commitment, contextual adaptation, supply chain decisions, and external incentives. Key interventions, including solar energy adoption, composting, and the formation of zero-waste partnerships, resulted in measurable reductions in energy use and landfill waste, along with improvements in guest satisfaction, operational efficiency, and local collaboration. Although it is subject to limitations typical of single-case designs, the study demonstrates how even modest sustainability efforts, when integrated into daily operations, can generate multiple types of outcomes (economic, environmental, and operational). The paper offers practical implications for tourism SMEs and policymakers and formulates propositions for future testing on sustainable innovation in the tourism sector. Full article

The rising demand for sustainable agriculture and circular resource management has intensified interest in converting wastewater sludge into value-added products. This review explores the transformation of sewage sludge into slow- and controlled-release fertilizers (CRFs), with a focus on biochar production and encapsulation technologies. Sewage sludge is rich in essential macronutrients (N, P, K), micronutrients, and organic matter, making it a promising feedstock for agricultural applications. However, its use is constrained by challenges including compositional variability, presence of heavy metals, pathogens, and emerging contaminants such as microplastics and PFAS (Per- and Polyfluoroalkyl Substances). The manuscript discusses a range of stabilization and conversion techniques, such as composting, anaerobic digestion, pyrolysis, hydrothermal carbonization, and nutrient recovery from incinerated sludge ash. Special emphasis is placed on coating and encapsulation technologies that regulate nutrient release, improve fertilizer efficiency, and reduce environmental losses. The role of natural, synthetic, and biodegradable polymers in enhancing release mechanisms is analyzed in the context of agricultural performance and soil health. While these technologies offer environmental and agronomic benefits, large-scale adoption is hindered by technical, economic, and regulatory barriers. The review highlights key challenges and outlines future perspectives, including the need for advanced coating materials, improved contaminant mitigation strategies, harmonized regulations, and field-scale validation of CRFs. Overall, the valorisation of sewage sludge into CRFs presents a viable strategy for nutrient recovery, waste minimization, and sustainable food production. With continued innovation and policy support, sludge-based fertilizers can become a critical component of the green transition in agriculture. Full article

Soil degradation and poor fertility severely constrain vegetation growth in urban ecosystems, particularly in compacted and nutrient-depleted tree pits. Mulching has emerged as an effective strategy to improve soil quality and regulate soil–microbe–plant interactions, yet the combined use of organic and inorganic mulching in urban landscapes remains underexplored. In this study, a one-year field experiment was conducted to evaluate the effects of four mulching treatments on soil bacterial community diversity and functional potential. Four treatments were applied green waste compost + wood chips (GW), green waste compost + wood chips + volcanic rocks (GWV), green waste compost + wood chips + pebbles (GWP), and a non-mulched control (CK). Organic mulching (GW) effectively reduced bulk density, enhanced cellulase and protease activities, increased bacterial community richness and balance, and enriched microbial genes associated with carbon and nitrogen metabolism, while organic–inorganic mulching further promoted soil nutrition and reshaped bacterial community structure. Soil pH, nitrogen content, and protease activity served as key drivers of bacterial community structure and function. These findings demonstrate that different mulching practices provide distinct ecological advantages, and together highlight the role of mulching in regulating soil–microbe–plant interactions and improving urban tree pit management. Full article

In the circular economy framework, municipal wastes are seen as secondary raw materials that can be used to fertilize agricultural soils. This study assessed the effect of different biowaste and green waste treatment schemes on P fertilizer value to learn about the optimal valorization of these feedstocks. The wastes were used either fresh, after composting or anaerobic digestion, or as biochars produced at various pyrolysis conditions. The fertilizer value was determined from the change in soil concentration of plant-available P (P_CAL) in incubation experiments with different soils and the temporal dynamics of fertilizer-induced growth and P accumulation of ryegrass in a pot experiment with eight harvests. The mode of waste treatment significantly influenced the P fertilizer value in the incubation and in the pot experiment. In the incubation experiment, the amendment-induced P_CAL increase varied between 22% and 33% of applied P on low-P acidic soil and between 55% and 88% of applied P on high-P acidic soil, whereby the amendment effects were mainly determined by their effects on soil pH. In the pot experiment with low-P acidic soil, the apparent P recovery in the plant biomass (APR) varied between 2% of applied P for fresh green waste and 42% for fluid digestate. The amendment effects on APR were not related to soil pH but to the P_CAL supply with the amendments and amendment effects on soil P supply. Our data show great potential for increasing the P fertilizer value of organic municipal waste materials through appropriate processing prior to application. Full article

Nature-Based Solutions (NBS) represent an alternative for achieving environmental and resilience goals in diverse global contexts with varying needs. As such, NBS can be understood as processes involving actions that promote circular economy (CE) strategies within their function. Therefore, this research aims to conduct a systematic literature review to identify and analyze the main NBS applied and explore how they are associated with CE strategies. This study performs a systematic literature review of NBS and their relationship with the CE using the PRISMA methodology, analyzing a total of 32 articles retrieved from the SCOPUS database. The main NBS include constructed wetlands, green infrastructure, and soil restoration and enrichment solutions. Constructed wetlands are linked to strategies such as recycling and reuse due to their role in treating urban and domestic wastewater for reuse, thereby increasing water availability. Green infrastructure is associated with strategies like redesign and reduction, as it involves the use of lower-impact materials and designs for rainwater harvesting and thermal comfort improvement. Soil enrichment and remediation solutions are connected to reuse and recycling strategies, as most derive from organic waste composting or microorganisms. NBS and CE strategies highlight how these solutions not only provide direct environmental benefits but also, when analyzed from a sustainability perspective, can offer social and economic benefits. Furthermore, understanding their relationship will facilitate their integration into regulations for transitioning toward circularity in industries and cities. The contribution of this article lies in synthesizing and systematizing the evidence on how NBS operationalizes CE strategies, identifying the main mechanisms and gaps, and proposing a conceptual model that can guide future research and policy design. Full article

With the rapid expansion of urban green spaces and the increasing amount of domestic waste, efficient and sustainable treatment of green waste (GW) and kitchen waste (KW) has become a pressing issue. Co-composting offers a green and low-carbon solution, yet a systematic understanding of its greenhouse gas (GHG) emission dynamics remains lacking. This study aims to investigate the impact of varying GW:KW ratios on GHG emissions during composting, in order to identify optimal mixing strategies and sup-port the development of low-carbon urban waste management systems. Six treatments with different GW:KW ratios (10:0, 9:1, 8:2, 7:3, 6:4, and 5:5) were evaluated under continuous aeration for 42 days. Results showed: (1) All treatments exhibited a typical composting temperature profile (mesophilic, thermophilic, cooling, maturation), with final seed germination index (GI) > 95% and significantly reduced E4/E6 ratios, indicating maturity. (2) When kitchen waste (KW) was ≤20%, cumulative GHG emissions slightly increased; KW ≥ 30% led to net reductions, with the 6:4 treatment (A4) achieving the highest decrease (17.44%) in total CO₂-equivalent emissions. In conclusion, maintaining KW at 40–50% optimally balances compost maturity and emission reduction, providing a viable strategy for the high-value utilization of urban organic waste and carbon mitigation. Full article

The exponential increase in global solid waste generation poses significant environmental, economic, and social challenges, particularly in rapidly urbanizing regions. Traditional waste management methods that focus on handling and disposal have proven unsustainable because of their negative impacts on air, soil, and water quality, and their contribution to greenhouse gas emissions. In response, the concept of zero-waste cities, rooted in circular economy principles, has gained increasing attention in recent years. This study proposes a comprehensive and integrated waste management system designed to optimize resource recovery across four distinct waste streams: household, healthcare, green/organic, and inert. The system integrates four specialized facilities: a Secondary Sorting Facility, Energy Recovery Facility, Composting Facility, and Inert Processing Facility, coordinated through a central Primary Sorting Hub. By enabling interconnectivity between these processing units, the system facilitates material cascading, maximizes the reuse and recycling of secondary raw materials, and supports energy recovery and circular nutrient flow. The anticipated benefits include enhanced operational efficiency, reduced environmental degradation, and generation of multiple revenue streams. However, the implementation of such a system faces challenges related to high capital investment, technological complexity, regulatory fragmentation, and low public acceptance. Overcoming these limitations will require strategic planning, stakeholder engagement, and adaptive governance. Full article