Waste, Volume 3, Issue 2 (June 2025) – 10 articles

In this study, a Life Cycle Assessment (LCA) was conducted to evaluate the environmental impact of osmotically dehydrated, fresh-cut, pre-packaged potatoes compared to conventional untreated ones. The case study focused on a small processing line in Naxos Island, Greece, aiming to extend shelf-life by up to 5 days. The analysis covered the full value chain, from cultivation to household consumption, considering changes in energy and material use, transport volumes, waste generation, and cultivation demand. Three scenarios were assessed: (i) conventional untreated potatoes, (ii) dehydrated potatoes using market glycerol, and (iii) dehydrated potatoes using glycerol from vegetable oil treatment. Systems and life cycle inventories (LCI) were modelled in OpenLCA v2.4 software with the ecoinvent v3.11 database, applying the Environmental Footprint (EF) method, v3.1. The selected impact categories included the following: global warming potential, water use, freshwater ecotoxicity, freshwater and marine eutrophication, energy resource use, particulate matter formation, and acidification. Results showed that applying osmotic dehydration (OD) improved environmental performance in most, but not all, categories. When market glycerol was used, some burdens increased due to glycerol production. However, using glycerol from vegetable oil treatment resulted in reductions of 25.8% to 54.9% across all categories compared to the conventional scenario. Overall, OD with alternative glycerol proved to be the most environmentally beneficial approach. Full article

The cement industry faces increasing energy costs and environmental pressures, driving the adoption of alternative fuels derived from waste materials. In Togo, approximately 350,000 t of end-of-life tires (ELT) are generated annually, creating significant environmental and health hazards through uncontrolled disposal and burning practices. This study investigated the technical feasibility and economic viability of incorporating waste tires as an alternative fuel in cement manufacturing. Tire-derived fuel (TDF) performance was evaluated by comparing pre-processed industrial tires with unprocessed ones, focusing on clinker production loss, elemental composition, heating values, and bulk density. The results demonstrate that TDF exhibits superior performance characteristics, with the highest heating values, and meets all the required specifications for cement production. In contrast, whole tire incineration fails to satisfy the recommended criteria, necessitating blending with conventional fuels to maintain clinker quality and combustion efficiency. The investigation revealed no significant adverse effects on production processes or clinker quality while achieving substantial reductions in nitrogen and sulfur oxide emissions. The experimental results were compared with the theoretical burnout times to optimize the shredding operations and injection methods. However, several challenges remain unaddressed, including the absence of streamlined handling processes, limited understanding of long-term ecological and health impacts, and insufficient techno-economic assessments. Future research should prioritize identifying critical aging points, investigating self-rejuvenating behaviors, and quantifying long-term environmental implications. These findings provide a foundation for developing computational models to optimize the mixing ratios of alternative and fossil fuels in cement manufacturing, offering significant environmental, economic, and societal benefits for the cement industry. Full article

Agricultural waste poses significant environmental, economic, and social challenges globally, with estimates indicating that 10–50% of agricultural products are discarded annually as waste. This review explores strategies for managing agricultural waste to mitigate its adverse impacts and promote sustainable development. Agricultural residues, such as those from sugarcane, rice, and wheat, contribute to pollution when improperly disposed of through burning or burying, contaminating soil, water, and air. However, these residues also represent untapped resources for bioenergy production, composting, mulching, and the creation of value-added products like biochar, bioplastics, single-cell protein and biobased building blocks. The paper highlights various solutions, including integrating agricultural waste into livestock feed formulations to reduce competition for human food crops, producing biofuels like ethanol and biodiesel from lignocellulosic materials, and adopting circular economy practices to upcycle waste into high-value products. Technologies such as anaerobic digestion for biogas production and gasification for synthesis gas offer renewable energy alternatives and ample feedstocks for gas fermentation while addressing waste management issues. Composting and vermicomposting enhance soil fertility, while mulching improves moisture retention and reduces erosion. Moreover, the review emphasizes the importance of policy frameworks, public-private partnerships, and farmer education in promoting effective waste management practices. By implementing these strategies, agricultural waste can be transformed into a resource, contributing to food security, environmental conservation, and economic growth. Full article

CO₂ emissions, a significant contributor to climate change, have spurred the exploration of sustainable solutions. One putative solution involves using recycled aggregates (RAs) from construction and demolition waste (CDW) to substitute natural sand in construction materials. This not only extends the life cycle of the waste but also reduces the use of natural resources. The potential to capture CO₂ in RAs presents a promising route to mitigate the environmental impact of the construction industry and contribute to its much anticipated decarbonization. This research takes a unique approach by investigating the incorporation of an amine-based additive—specifically 2-amino-2-methyl-1,3-propanediol (AMPD)—to enhance CO₂ capture into a real-case RA from recycling plants, transforming CDW with low carbon-capture potential into a highly reactive CO₂ capture material. Through TG analysis, FTIR-ATR and the combination of both (TG-FTIR), we were able to validate the use of RA materials as a support medium and quantify the CO₂ capture potential (12%) of the AMPD amine; a dual valorization was achieved: new value was added to low-quality CDW and we enhanced CO₂ sequestration, offering hope for a more sustainable future. Full article

This investigation aimed at studying the effect of enrichment of corn oil, which was used as a model lipid, using waste orange peel (WOP), polyphenolic antioxidants, to provide effective shielding against oxidation. An initial comparison of two modes, a stirred-tank and an ultrasound-assisted one, evidenced that the latter was more efficacious in enriching corn oil with total polyphenols. However, detailed examination of the polyphenolic composition revealed that the oil enriched with the stirred-tank mode may have almost two times higher polyphenolic content, which totaled 109 mg per kg of oil. The major polyphenolic constituents identified were polymethylated flavones, but also ferulic acid and naringenin. Oil stability trials, including the monitoring of peroxide value and p-anisidin value, demonstrated that the oil enriched with WOP polyphenols using the stirred-tank mode exhibited significantly higher oxidative resilience compared to control (neat oil), but also compared to the oil enriched using ultrasonication. Furthermore, it was observed that when neat oil was ultrasonicated, it also displayed exceptional stability against oxidation. Based on the outcome of this study, it is recommended that WOP, owed to its richness in lipophilic flavonoids, might be an ideal candidate for edible oil fortification, which could provide the oil with natural powerful antioxidants. Such a process could lend oils high oxidative resilience, but also functional ingredients. Full article

The growing challenges of freshwater scarcity and the high generation of agro-industrial waste, particularly from fruit and vegetable (F&V) processing, pose significant threats to the sustainability of global food systems. F&V waste, which represents a major portion of the 1.3 billion tons of annual food waste, is characterized by a high moisture content (80–95%), making it a largely overlooked but promising source of water recovery. This review critically assesses the techno-economic and environmental feasibility of extracting water from moisture-rich agro-industrial waste streams. Potential technologies such as solar distillation and membrane separation are evaluated to determine their capacity to treat complex organic effluents and recover high-quality water. The potential end uses of reclaimed water in all sectors are explored, focusing on agricultural irrigation, fertigation, industrial reuse and environmental restoration. This study addresses a key research gap and proposes the reclassification of agro-industrial waste as a viable water resource aligned with circular bioeconomy principles and Sustainable Development Goals (SDGs) 6 and 12. Full article

Methane is a powerful greenhouse gas and short-lived climate pollutant generated in landfills. In this work, five first-order decay models were implemented to estimate the methane emissions from a landfill near Oaxaca city. The five models were the simple first-order decay model, the modified first-order decay model, the multiphase model, the LandGem model, and the Intergovernmental Panel on Climate Change (IPCC) model. An autoregressive integrated moving average (ARIMA) model was built to predict waste generation, and a gravimetric method was used to estimate the volume of stored waste. The ARIMA model correctly predicted the generation of municipal solid waste, calculating 108,202 tons of solid waste in the landfill for the year 2022. In terms of the models and considering the experimental data measured in 2020, the simple model and the simple modified model were more accurate, with 3.50 × 10⁶ m³ (relative error = 1.0) and 3.76 × 10⁶ m³ of methane (relative error = 6.3), respectively. The multiphase model calculated a value of 3.09 × 10⁶ m³ of methane (relative error = 12.6), the LandGEM model calculated a value of 4.97 × 10⁶ m³ (40.7), and the IPCC model calculated a value of 3.19 × 10⁶ m³ (relative error = 9.7). The LandGEM model was improved when the standard values proposed by the Environmental Protection Agency (EPA) were considered. According to the simple model and the simple modified model, by 2050, the landfill will emit 1.22 × 10⁶ m³ and 1.37 × 10⁶ m³, demonstrating that important methane emissions will be released in the decades to come. This information is important for the implementation of methane mitigation strategies, to which Mexico has committed in the Global Methane Initiative. Full article

Black beans (Phaseolus vulgaris L.) are one of the most consumed legumes worldwide. Black beans are rich in proteins, vitamins, minerals, and polyphenolic compounds. The present study aims to valorize black beans for the extraction of polyphenolic compounds using solid-state fermentation (SSF) from Aspergillus niger GH1. A physicochemical analysis of black beans was performed. Fermentation kinetics was performed to establish the best accumulation time of condensed polyphenols. A two-level Plackett–Burman experimental design was used to evaluate the culture conditions (temperature, humidity, inoculum, particle size, pH and salt concentration) for the accumulation of condensed polyphenols. The results of the physicochemical analysis showed that black beans can be used as a substrate in the SSF process. In addition, the best time for the accumulation of condensed polyphenols was 48 h. Treatment 5 achieved an accumulation of 21.04 mg/g of condensed polyphenols. While the factors of particle size, humidity, and temperature had a significant effect on the accumulation of condensed polyphenols. It is concluded that the SSF process is an efficient and eco-friendly extraction method for obtaining bioactive molecules with potential applications in the pharmaceutical, food, and cosmetic industries. Full article

Pretreatment of lignocellulosic biomass remains the primary obstacle to the profitable use of this type of biomass in biorefineries. The challenge lies in the recalcitrance of the lignin-carbohydrate complex to pretreatment, especially the difficulty in removing the lignin to access the carbohydrates (cellulose and hemicellulose). This study had two objectives: (i) to investigate the effect of reactive extrusion on lignocellulosic biomass in terms of delignification percentage and the structural characteristics of the resulting extrudates, and (ii) to propose a novel pretreatment approach involving extrusion technology based on the results of the first objective. Two types of biomasses were used: agricultural residue (corn stover) and forest residue (black spruce chips). By optimizing the extrusion conditions via response surface analysis (RSA), the delignification percentages were significantly improved. For corn stover, the delignification yield increased from 2.3% to 27.4%, while increasing from 1% to 25.3% for black spruce chips. The highest percentages were achieved without the use of sodium hydroxide and for temperatures below 65 °C. Furthermore, the optimized extrudates exhibited important structural changes without any formation of p-cresol, furfural, and 5-hydroxymethylfurfural (HMF) (enzymes and microbial growth-inhibiting compounds). Acetic acid however was detected in corn stover extrudate. The structural changes included the disorganization of the most recalcitrant functional groups, reduction of particle sizes, increase of specific surface areas, and the appearance of microscopic roughness on the particles. Analyzing all the data led to propose a new promising approach to the pretreatment of lignocellulosic biomasses. This approach involves combining extrusion and biodelignification with white rot fungi to improve the enzymatic hydrolysis of carbohydrates. Full article

This study explores both pyrometallurgical and hydrometallurgical methods for decarbonizing and recovering valuable metals from bauxite residue, with hydrogen plasma reduction and direct acid leaching as the primary approaches. The goal is to offer innovative techniques for extracting metals from bauxite residue, a by-product of the Bayer process, which cannot be disposed of in an environmentally sustainable manner. Additionally, reducing the volume of bauxite residue through combined treatments is a key objective. In contrast to traditional carbon-based reductive melting, which generated significant CO₂ emissions, hydrogen is now being investigated as a cleaner alternative. Through hydrogen plasma reduction, approximately 99.9% of iron is recovered as crude metallic iron, which can be easily separated from the slag containing other valuable metals. Thermochemical analysis was used to predict slag formation and chemical analysis of slag during hydrogen reduction. To further recover metals like aluminum and titanium, the slag is subjected to sulfuric acid leaching under high-pressure of oxygen in an autoclave avoiding silica gel formation. The results demonstrated a leaching efficiency of 93.21% for aluminum and 84.56% for titanium, using 5 mol/L sulfuric acid at 150 °C, with almost complete iron recovery. Assisted ultrasound leaching of slag with sulphuric acid under atmospheric pressure leads to 54% leaching efficiency of titanium. Full article