Search Results (2,087)

Efficient and clean utilization remains a pivotal development focus within the coal industry. Nevertheless, the application of weakly caking coal results in energy loss due to the caking property, thereby leading to a waste of resources. This paper, therefore, concentrates on the caking property, offering insights into the relevant caking mechanism, evaluation indexes, and regulation technologies associated with it. The caking mechanism delineates the transformation process of coal into coke. During pyrolysis, the active component generates the plastic mass in which gas, liquid, and solid phases coexist. With an increase in temperature, the liquid phase is diminished gradually, causing the inert components to bond. Based on the caking mechanism, evaluation indexes such as that characteristic of char residue, the caking index, and the maximal thickness of the plastic layer are proposed. These indexes are used to distinguish the strength of the caking property. However, they frequently exhibit a poor differentiation ability and high subjectivity. Additionally, some technologies have been demonstrated to regulate the caking property. Technologies such as rapid heating treatment and hydrogenation modification increase the amount of plastic mass generated, thereby improving the caking property. Meanwhile, technologies such as mechanical breaking and pre-oxidation reduce the caking property by destroying agglomerates or consuming plastic mass. Full article

This study aims to evaluate eco-innovative solutions in the fertilizer industry that allow for waste valorization in the context of a resource-efficient circular economy. A comprehensive reuse strategy was developed for low-rank peat and post-cultivation horticultural mineral wool, involving the extraction of valuable humic substances from peat and residual nutrients from used mineral wool, followed by the use of both post-extraction residues to produce organic–mineral substrates. The resulting products/semifinished products were characterized in terms of their composition and properties, which met the requirements necessary to obtain the admission of this type of product to the market in accordance with the Regulation of the Minister for Agriculture and Rural Development of 18 June 2008 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws No 119, item 765). Elemental analysis, FTIR spectroscopy, and solid-state CP-MAS ¹³C NMR spectroscopy suggest that post-extraction peat has a relatively condensed structure with a high C content (47.4%) and a reduced O/C atomic ratio and is rich in alkyl-like matter (63.2%) but devoid of some functional groups in favor of extracted fulvic acids. Therefore, it remains a valuable organic biowaste, which, in combination with post-extraction waste mineral wool in a ratio of 60:40 and possibly the addition of mineral nutrients, allows us to obtain a completely new substrate with a bulk density of 264 g/m³, a salinity of 7.8 g/dm³ and a pH of 5.3, with an appropriate content of heavy metals and with no impurities, meeting the requirements of this type of product. A liquid fertilizer based on an extract containing previously recovered nutrients also meets the criteria in terms of quality and content of impurities and can potentially be used as a fertilizing product suitable for agricultural crops. This study demonstrates a feasible pathway for transforming specific waste streams into valuable agricultural inputs, contributing to environmental protection and sustainable production. The production of a new liquid fertilizer using nutrients recovered from post-cultivation mineral wool and the preparation of an organic–mineral substrate using post-extraction solid residue is a rational strategy for recycling hard-to-biodegrade end-of-life products. Full article

Agriculture is one of the most important sectors of the global economy, but it increasingly faces sustainability challenges in meeting rising food demands. The intensive use of mineral fertilizers not only improves yields, but also causes negative environmental impacts such as increasing greenhouse gas emissions, water eutrophication, and soil degradation. To develop more sustainable solutions, the focus is on organic fertilizers, which are produced using waste and biostimulants such as amino acids. The aim of this study was to develop and characterize liquid nitrogen–calcium–magnesium fertilizers produced by decomposing dolomite with nitric acid followed by further processing and to enrich them with a powdered amino acid concentrate Naturamin-WSP and liquid extracts from digestate, a by-product of biogas production. Nutrient-rich extracts were obtained using water and potassium hydroxide solutions, with the latter proving more effective by yielding a higher organic carbon content (4495 ± 0.52 mg/L) and humic substances, which can improve soil structure. The produced fertilizers demonstrated favourable physical properties, including appropriate viscosity and density, as well as low crystallization temperatures (eutectic points from –3 to –34 °C), which are essential for storage and application in cold climates. These properties were achieved by adjusting the content of nitrogenous compounds and bioactive extracts. The results of the study show that liquid fertilizers enriched with organic matter can be an effective and more environmentally friendly alternative to mineral fertilizers, contributing to the development of the circular economy and sustainable agriculture. Full article

Bamboo shoot boiled liquid (BSBL), a processing byproduct containing soluble proteins, peptides, amino acids, carbohydrates, and phenolics, is typically discarded, causing resource waste and environmental issues. This study analyzed metabolic changes in BSBL during Pediococcus pentosaceus B49 fermentation. The result of partial least squares discriminant analysis (PLS-DA) revealed significant metabolite profile differences across fermentation times (0 h, 24 h, 48 h, 72 h, 96 h). The most substantial alterations occurred within the first 24 h, followed by stabilization. Compared to unfermented BSBL, fermented samples exhibited significantly elevated signal intensities for 5,7-dimethoxyflavone, cinnamic acid, 3,4-dihydro-2H-1-benzopyran-2-one, 6,8-dimethyl-4-hydroxycoumarin, and 2-hydroxycinnamic acid (p < 0.05), showing upward trends over time. Conversely, (+)-gallocatechin intensity decreased gradually. Bitter peptides, such as alanylisoleucine, isoleucylisoleucine, leucylvaline, and phenylalanylisoleucine, in BSBL exhibited a significant reduction following fermentation with P. pentosaceus B49 (p < 0.05). KEGG enrichment indicated tyrosine metabolism (ko00350) and arginine/proline metabolism (ko00330) as the most impacted pathways. These findings elucidate metabolic regulation in BSBL fermentation, supporting development of functional fermented bamboo products. Full article

Digestate valorization is essential for sustainable waste management and circular economy strategies, yet large-scale adoption faces technical, economic, and environmental challenges. Beyond waste-to-energy conversion, digestate is a valuable soil amendment, enhancing soil structure and reducing reliance on synthetic fertilizers. However, its agronomic benefits depend on feedstock characteristics, treatment processes, and application methods. This study reviews digestate composition, treatment technologies, regulatory frameworks, and environmental impact assessment through Life Cycle Assessment. It analyzes the influence of functional unit selection and system boundary definitions on Life Cycle Assessment outcomes and the effects of feedstock selection, pretreatment, and post-processing on its environmental footprint and fertilization efficiency. A review of 28 JCR-indexed articles (2018–present) analyzed LCA studies on digestate, focusing on methodologies, system boundaries, and impact categories. The findings indicate that Life Cycle Assessment methodologies vary widely, complicating direct comparisons. Transportation distances, nutrient stability, and post-processing strategies significantly impact greenhouse gas emissions and nutrient retention efficiency. Techniques like solid–liquid separation and composting enhance digestate stability and agronomic performance. Digestate remains a promising alternative to synthetic fertilizers despite market uncertainty and regulatory inconsistencies. Standardized Life Cycle Assessment methodologies and policy incentives are needed to promote its adoption as a sustainable soil amendment within circular economy frameworks. Full article

Concern over the presence of pharmaceutical waste in the environment has prompted research into the management of emerging organic micropollutants (EOMs). In response, sustainable technologies have been applied as alternatives to reduce the effects of these contaminants. This study investigated the capacity of filamentous fungi isolated from iron mine soil in the Amazon region to biodegrade the drug chloroquine diphosphate. An initial screening assessed the growth of four fungal strains on solid media containing chloroquine diphosphate: Trichoderma pseudoasperelloides CBMAI 2752, Penicillium rolfsii CBMAI 2753, Talaromyces verruculosus CBMAI 2754, and Penicillium sp. cf. guaibinense CBMAI 2758. Among them, Penicillium sp. cf. guaibinense CBMAI 2758 was selected for further testing in liquid media. A Box–Behnken factorial design was applied with three variables, pH (5, 7, and 9), incubation time (5, 10, and 15 days), and chloroquine diphosphate concentration (50, 75, and 100 mg·L⁻¹), totaling 15 experiments. The samples were analyzed by gas chromatography–mass spectrometry (GC-MS). The most effective conditions for chloroquine biodegradation were pH 7, 100 mg·L⁻¹ concentration, and 10 days of incubation. Four metabolites were identified: one resulting from N-deethylation M1 (N4-(7-chloroquinolin-4-yl)-N1-ethylpentane-1,4-diamine), two from carbon–carbon bond cleavage M2 (7-chloro-N-ethylquinolin-4-amine) and M3 (N1,N1-diethylpentane-1,4-diamine), and one from aromatic deamination M4 (N1-ethylbutane-1,4-diamine) by enzymatic reactions. The toxicity analysis showed that the products obtained from the biodegradation of chloroquine were less toxic than the commercial formulation of this compound. These findings highlight the biotechnological potential of Amazonian fungi for drug biodegradation and decontamination. Full article

The olive oil industry, a key component of Southern Europe’s agricultural sector, generates large amounts of by-products during processing, including olive leaves, branches, stones, and seeds. In the context of growing environmental concerns and limited natural resources—particularly in the Mediterranean regions—there is increasing interest in circular economy approaches that promote the valorization of agricultural residues. These by-products are rich in bioactive compounds, particularly phenolics such as oleuropein and hydroxytyrosol, which are well known for their antioxidant and anti-inflammatory activities. This study aimed to evaluate the phenolic content and antioxidant capacity of by-products from three olive cultivars using high-performance liquid chromatography with photodiode array detection (HPLC–PDA) and mass spectrometry (MS). The leaves and seeds, particularly from the “Cobrança” and a non-identified variety, presented the highest antioxidant activity, as well as the highest concentration of phenolic compounds, demonstrating once again the direct relationship between these two parameters. The identification of the compounds present demonstrated that the leaves and branches have a high diversity of phenolic compounds, particularly secoiridoids, flavonoids, phenylpropanoids, phenylethanoids, and lignans. An inverse relationship was observed between the chlorophyll and carotenoid content and the antioxidant activity, suggesting that phenolic compounds, rather than pigments, are the major contributors to antioxidant properties. Therefore, the by-products of the olive oil industry are a valuable source of sustainable bioactive compounds for distinct industrial sectors, such as the food, nutraceutical, and pharmaceutical industries, aligning with the European strategies for resource efficiency and waste reduction in the agri-food industries. Full article

This study evaluated and compared two encapsulation techniques—co-crystallization and ionic gelation—for stabilizing bioactive components derived from lavender distillation residues. Utilizing aqueous ethanol extraction (solid residues) and concentration (liquid residues), phenolic-rich extracts were incorporated into encapsulation matrices and processed under controlled conditions. Comprehensive characterization included encapsulation efficiency (Ef), antioxidant activity (AA), moisture content, hygroscopicity, dissolution time, bulk density, and color parameters (L*, a*, b*). Co-crystallization outperformed ionic gelation across most criteria, achieving significantly higher Ef (>150%) and superior functional properties such as lower moisture content (<0.5%), negative hygroscopicity (−6%), and faster dissolution (<60 s). These features suggested enhanced physicochemical stability and suitability for applications requiring long shelf life and rapid solubility. In contrast, extruded beads exhibited high moisture levels (94.0–95.4%) but allowed better control over morphological features. The work introduced a mild-processing approach applied innovatively to the valorization of lavender distillation waste through structurally stable phenolic delivery systems. By systematically benchmarking two distinct encapsulation strategies under equivalent formulation conditions, this study advanced current understanding in bioactive microencapsulation and offers new tools for developing functional ingredients from aromatic plant by-products. Full article

Vegetable oils are an important alternative to the massive use of fuels and lubricants from non-renewable energy sources. In this study, the physicochemical properties of coconut oil and waste cooking oil are investigated for biofuels and biolubricant applications. A transesterification of both oils was reached, and the transesterified oils were characterized by infrared analysis and gas chromatography. The lubricant performances of these oils have been evaluated using a ball-on-plane tribometer under an ambient atmosphere. Different formulations were developed using graphite particles as solid additive. Each initial and modified oil has been investigated as a base oil and as a liquid additive lubricant. The best friction reduction findings have been obtained for both initial oils as liquid additives, highlighting the key role of triglycerides in influencing tribological performances. Full article

Pyrolysis technology currently serves as a significant method for recycling and reducing waste tires. In this paper, in order to improve the heat transfer efficiency during the pyrolysis of waste tires in a horizontal rotary furnace and the yield of pyrolysis oil, the effect laws of tire particle size, rotary furnace rotation speed, enhanced heat transfer materials, and adding spiral fins on heat transfer performance and pyrolysis product distribution were studied, respectively. The innovation lies in two aspects: first, aiming at the problems of slow heat transfer and low pyrolysis efficiency in horizontal rotary furnaces, we identified technical measures through experiments to enhance heat transfer, thereby accelerating pyrolysis and reducing energy consumption; second, with the goal of increasing high-value pyrolysis oil yield, we determined optimal operating parameters to improve economic and sustainability outcomes. The results showed that powdered particles of waste tires were heated more evenly during the pyrolysis process, which increased the overall heat transfer coefficient and the proportion of liquid products. When the rotational speed of the rotary pyrolysis furnace exceeded 2 rpm, there was sufficient contact between the material and the furnace wall, which was beneficial to the improvement of heat transfer performance. Adding heat transfer enhancement materials such as carborundum and white alundum could improve the heat transfer performance between the pyrolysis furnace and the material. Notably, a rotational speed of 3 rpm and carborundum were used as a heat transfer enhancement material with powdered waste tire particles during the pyrolysis process; the overall heat transfer coefficient was the highest, which was 16.89 W/(m²·K), and the proportion of pyrolysis oil products was 46.1%. When spiral fins were installed, the comprehensive heat transfer coefficient was increased from 12.78 W/(m²·K) to 16.32 W/(m²·K). The experimental results show that by increasing the speed of the pyrolysis furnace, adding heat transfer enhancing materials with high thermal conductivity to waste tires, and appropriate particle size, the heat transfer performance and pyrolysis rate can be improved, and energy consumption can be reduced. Full article

Boehmite has been widely used in theoretical research and industry, especially for hazardous material processing. For the liquid-phase treating process, the interfacial properties of boehmite are believed to be affected by pH conditions, which change its physicochemical behavior. However, molecular-level detection on cluster ions is challenging when using bulk approaches. Herein we employ in situ vacuum ultraviolet single-photon ionization mass spectrometry (VUV SPI-MS) coupled with a vacuum-compatible microreactor system for analysis at the liquid–vacuum interface (SALVI) to investigate the solute molecular composition of boehmite under different pH conditions for the first time. The mass spectral results show that more complex clustering of solute molecules exists at the solid–liquid (s–l) interface than conventionally perceived in a “simple” aqueous solution. Besides solute ions, such as boehmite molecules and fragments, the composition and appearance energies of these newly discovered solvated cluster ions are determined by VUV SPI-MS in different pH solutions. We offer new results for the pH-dependent effect of boehmite and provide insights into a more detailed solvation mechanism at the s–l interface. By comparing the key products under different pH conditions, fundamental understanding of boehmite dissolution is revealed to assist the engineering design of waste processing and storage solutions. Full article

The growing environmental concerns associated with petroleum-based plastics require the development of sustainable, biodegradable alternatives. Polyhydroxyalkanoates (PHAs), a family of biodegradable bioplastics, offer a promising potential as eco-friendly substitutes due to their renewable origin and favorable degradation properties. This research investigates the use of synthetic condensate, mimicking the liquid fraction from drying and shredding of household food waste, as a viable substrate for PHA production using mixed microbial cultures. Two draw-fill reactors (DFRs) were operated under different feed organic concentrations (2.0 ± 0.5 and 3.8 ± 0.6 g COD/L), maintaining a consistent carbon-to-nitrogen ratio to selectively enrich microorganisms capable of accumulating PHAs through alternating nutrient availability and deficiency. Both reactors achieved efficient organic pollutant removal (>95% soluble COD removal), stable biomass growth, and optimal pH levels. Notably, the reactor with the higher organic load (DFR-2) demonstrated a modest increase in PHA accumulation (19.05 ± 7.18%) compared to the lower-loaded reactor (DFR-1; 15.19 ± 6.00%), alongside significantly enhanced biomass productivity. Polymer characterization revealed the formation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), influenced by the substrate composition. Microbial community analysis showed an adaptive shift towards Proteobacteria dominance, signifying successful enrichment of effective PHA producers. Full article

The development of slow-release fertilizers (SRFs) based on production residues is a promising strategy to improve nutrient use efficiency and promote circular economy practices in agriculture. In this study, a series of experimental formulations were designed and tested using pumice scraps, liquid and dried blood, and bone meal, aiming at producing sustainable and low-cost N-P-K SRFs. These were processed through mixing and granulation, both in the laboratory and on a semi-industrial scale. The formulations were evaluated through release tests in 2% citric acid solution simulating the acidic conditions of the rhizosphere, and in acetic acid to assess potential nutrient leaching under acid rain conditions. The results showed a progressive cumulative release of macronutrients (NPKs), ranging from approximately 8% at 24 h to 73% after 90 days for the most effective formulation (WBF6). Agronomic trials on lettuce confirmed the effectiveness of WBF6, resulting in significant biomass increases compared with both the untreated control and a conventional fertilizer. The use of livestock waste and minerals facilitated the development of a scalable product aligned with the principles of sustainable agriculture. The observed release behavior, combined with the simplicity of production, positions these formulations as a promising alternative to conventional slow-release fertilizers. Full article

The olive oil sector constitutes a fundamental pillar in the Mediterranean region from socio-economic and cultural perspectives. Nonetheless, it produces significant amounts of waste, leading to numerous environmental issues. These waste streams contain valuable compounds that can be recovered and utilized as inputs for various applications. This study introduces a novel value chain for olive wastes, focused on extracting lignin from olive pomace by ionic liquids and polyphenols from olive mill wastewater, which are then incorporated as hybrid nanoparticles in the formulation of an innovative starch-based biofertilizer. This biofertilizer, obtained by using residual wastewater as a source of soluble nitrogen, acting at the same time as a plasticizer for the biopolymer, was demonstrated to surpass traditional NPK biofertilizers’ efficiency, allowing for root growth and foliage in drought conditions. In order to recognize the environmental impact due to its production and align it with the technical output, the circularity and environmental performance of the proposed system were innovatively evaluated through a combination of Life Cycle Assessment (LCA) and the Material Circularity Indicator (MCI). LCA results indicated that the initial upcycling process was potentially characterized by significant hot spots, primarily related to energy consumption (>0.70 kWh/kg of water) during the early processing stages. As a result, the LCA score of this preliminary version of the biofertilizer may be higher than that of conventional commercial products, due to reliance on thermal processes for water removal and the substantial contribution (56%) of lignin/polyphenol precursors to the total LCA score. Replacing energy-intensive thermal treatments with more efficient alternatives represents a critical area for improvement. The MCI value of 0.84 indicates limited potential for further enhancement. Full article

The agro-industrial sector produces large amounts of by-products that have a high environmental impact, so it has become essential to recover food waste at all levels. This is because it often contains bioactive molecules that can be a valuable source of new products such as animal feed, biopolymers, or products for human use, (e.g., cosmetics and nutraceuticals) due to its antioxidant, antimicrobial, and anti-inflammatory properties. Advanced analytical methodologies such as liquid chromatography coupled to mass spectrometry (LC-MS) are crucial for the characterisation of bioactive chemicals in these waste materials. LC-MS enables both targeted and untargeted metabolomic approaches, facilitating the identification and quantification of a wide range of secondary metabolites, including polyphenols, flavonoids, alkaloids, and terpenoids. The choice of extraction methodology is essential for the precise identification and quantification of these metabolites. This study provides an overview of LC-MS as an effective tool for analysing complex extracts derived from plant waste, discussing both methodological aspects and typical bioactive metabolites identified, and offering examples of their potential applications in cosmeceutics. Full article