Biomass Conversion and Biorefinery最新文献

Biochar production from agricultural and forestry residues has expanded rapidly, but integration among research trends, production conditions, material properties, and large-scale implementation remains limited. This review combined bibliometric analysis with a critical synthesis of studies published between 2015 and 2025 and indexed in Scopus and Web of Science. After screening, 1,904 articles were included in the bibliometric analysis; 1,130 provided technical information on biochar production and properties, and 119 addressed implementation and scale-up. Scientific output increased 6.6-fold over the study period, accompanied by thematic diversification around thermochemical conversion, biochar properties, and environmental and agronomic applications. Agricultural and agro-industrial residues predominated, and pyrolysis was the most frequently reported conversion route. Under comparable within-study conditions, increasing temperature tended to reduce biochar yield and volatile matter while increasing fixed carbon and ash contents, and was also associated with carbon enrichment, lower H/C and O/C ratios, and higher pH and specific surface area. However, residence time, heating rate, atmosphere, reactor configuration, and operating mode were reported less frequently, limiting comparability among studies. Evidence related to implementation remained fragmented: 75.6% of the studies addressed only one analytical dimension, whereas 5.9% integrated three or more. This contrast highlights a gap between experimental knowledge of biochar production and properties and its translation into technically viable and scalable systems. Progress toward scale-up requires integrated assessments of process conditions, product characteristics, logistics, environmental performance, economic feasibility, standardization, and operational safety.

Hydrothermal carbonization (HTC) is an advantageous and potentially environmentally beneficial approach for the conversion of wet biomass and waste streams into a value-added solid product referred to as hydrochar. Although hydrochar composition and properties generated from the carbonization of a variety of feedstocks have been well-studied, there is a need for understanding whether hydrochar requires further refinement and/or treatment prior to being used in environmental applications, particularly when using the hydrochar as a soil amendment. In this study, work focused on understanding potential issues associated with using hydrochar generated from the carbonization of food wastes as a soil amendment and understanding how waste composition may influence the need for hydrochar post-processing. To accomplish this, laboratory-scale experiments investigating the carbonization of different components and mixtures of food waste (e.g., grains, vegetables, fruits) at different reaction temperatures (200 °C and 250 °C) for a time of four hours were conducted. The hydrochar was separated from the process water, dried, and subjected to sequential deionized water washing to understand the release of phytotoxic compounds from the hydrochar. Results of this study indicate that post-processing food waste hydrochar by water washing can sufficiently remove leachable phytotoxic compounds while preserving carbon and nitrogen solid content and maintaining a recommended C: N ratio for carbonaceous soil amendment application. The cumulative washing ratio required to remove phytotoxic effects depends on feedstock and HTC processing temperature.

Selective production of xylo-oligosaccharides (XOS) from corncob is hindered by secondary degradation during acid hydrolysis. Here, a citric acid/sodium citrate (CA/SC) conjugate acid-base system was developed for XOS-oriented fractionation of corncob. Compared with the citric acid hydrolysis, the optimal CA/SC hydrolysis increased the XOS yield from 44.3% to 50.5%, indicating a more favorable hydrolysis environment for XOS accumulation. Subsequent endoxylanase hydrolysis further upgraded residual high-degreesoluble oligomers and increased the XOS yield to 60.2%, with clear enrichment of xylobiose and xylotriose. Meanwhile, the pretreatment selectively removed hemicellulose while largely preserving glucan, producing cellulose-rich solid residues with enhanced enzymatic digestibility. Cellulase hydrolysis of residues gave glucose and xylose yields of 89.5% and 75.5%, respectively. Mass balance based on 1000 g of raw corncob gave 185.4 g XOS, 329.2 g glucose, and a lignin-rich final residue, demonstrating the potential of the CA/SC system for integrated corncob valorization.

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Dried coffee cherry milling generates large volumes of residue that are commonly thrown away and decomposed near processing plants, creating a disposal burden for small-scale processors. This study evaluated the sustainable valorisation of coffee-milling-waste biomass (CMWbm) into biochar to be used as fertilizer carriers. Biochar was produced from CMWbm using a muffle furnace (mCMWbc) and a laboratory-scale pyrolysis unit (pCMWbc), at 400 °C. Urea was loaded onto both biochars by impregnation method at 1:1 and 1:0.5 urea: biochar mass ratios. The biomass, biochars and urea-loaded biochar were characterized by proximate and ultimate analyses, TGA, FT-IR, XRD, BET surface area, SEM-EDX, and physicochemical studies. CMWbm properties showed its suitability as feedstock for thermochemical conversion. Biochar yield was 30.78% (mCMWbc) and 50.42% (pCMWbc) and was thermally stable, mesoporous and rich in reactive functional groups. Following urea loading, total nitrogen was 23.95 to 31.83% across four formulations. In a short-term urea dissolution test, free urea dissolved in 30 min, whereas the urea-loaded biochar formulations released slowly (~ 75% cumulative release within 16 h); 1:1 outperformed 1:0.5. Kinetic modeling demonstrated a shift from first-order dissolution of urea to quasi-Fickian transport at low biochar and Higuchi-governed Fickian diffusion at high biochar content. These results suggest that coffee-milling waste can be valorised as a urea carrier. However, as this study was restricted to physicochemical characterization and short-term dissolution tests, the formulations are referred to as biochar-based urea instead of slow-release fertilizers until soil incubation, leaching, and plant-response studies are performed to validate.

The rate of agro-industrial waste production demands efficient bioconversion processes for nutrient recovery. In this study, bioconversion efficiency, nutrient conversion, and micronutrient upgrading of black soldier fly larvae (BSFL; Hermetia illucens) were examined when fed six different tropical residues, which were carrot waste, mango peel, rice bran, wheat bran, palm kernel cake, and palm kernel fibre. Growth performance, waste reduction, proximate composition, and carotenoid bioaccumulation were examined to identify assimilation mechanisms of BSFL with different substrates. Significant variations were governed by nutrient bioavailability and matrix complexity rather than bulk concentration. Carrot waste achieved the highest waste reduction (84.73%), likely attributable to low matrix complexity. Maximum biomass gain (382.143%) occurred in wheat bran-fed larvae, reflecting balanced macronutrient accessibility. Protein content peaked in palm kernel cake-fed larvae (28.25%), while maximum lipid accumulation (29.16%) occurred in mango peel-fed larvae, suggesting that differences in the nutritional composition of the substrates may have contributed to variations in nutrient accumulation among the larvae. Maximum carotenoid bioaccumulation occurred in mango peel (2.12 mg/kg) and carrot waste (1.98 mg/kg), with rice bran exhibiting the highest bioaccumulation factor (1.29). Integrated evaluation using the Unified Resource Recovery Index identified carrot waste (URRI = 46.15) and wheat bran (URRI = 41.87) as most effective for simultaneous waste valorization and nutrient recovery. Fibrous substrates (palm kernel fibre, URRI = 18.59) imposed physical barriers that decoupled nutrient intake from assimilation. In conclusion, substrate type influences BSFL bioconversion, nutrient recovery, and bioactive compound accumulation, and substrate-specific selection may therefore be important for optimizing resource recovery and waste valorization.

To overcome the limited fermentation potential of low organic waste activated sludge (WAS) and the acidification imbalance of food waste (FW), an alkaline-assisted co-fermentation system was established to systematically investigate the regulatory effects of CaO₂ on WAS-FW co-fermentation under different alkaline conditions. The results showed that hydrolysis and acidification in the Ca²⁺-based alkaline fermentation system alone gradually declined with prolonged fermentation, whereas the Na⁺-based system remained relatively stable. The regulatory effects of CaO₂ strongly depended on the type of alkaline agent. Compared with the Na⁺-based system, CaO₂ significantly enhanced hydrolysis in the Ca²⁺-based system, increasing protein and polysaccharide release by 2.84 and 1.79 times, respectively. Meanwhile, short-chain fatty acids (SCFAs) accumulation increased to 21.85 times that of the corresponding control, but decreased to 0.74 time in the Na⁺-based system. In the Ca²⁺-based system, CaO₂ significantly enhanced the activities of key enzymes, including protease, alkaline phosphatase, and acetate kinase, and increased superoxide dismutase activity, potentially alleviating oxidative stress during fermentation. Function microbial further revealed that CaO₂ selectively enriched Alkalibacterium (49.83%) and Actinotalea (11.36%) in the Ca²⁺-based system, whereas Corynebacterium (24.87%) and Erysipelothrix (40.34%) were predominantly enriched in the Na⁺-based system. Overall, CaO₂ exhibited distinct cation-dependent synergistic effects and promoted SCFAs production through a cascade of “targeted hydrolysis-key enzyme activation-functional microbial succession,” providing a novel strategy for high-value resource recovery from organic solid wastes and targeted SCFAs production.

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In the context of the current global energy crisis and climate change, biochar composites have emerged as the most unique sustainable solution. These materials, obtained by the controlled thermal dissociation of biomass (pyrolysis), have high surface area, unique porous structure, and characteristic of chemical modification. This paper critically analyzes the synthesis methods of biochar compounds and the physical, chemical, and biotechnology that optimize their surface properties. This study will examine the conductivity of electrochemical fuel storage devices (super adsorption capacity in hydrogen storage and their thermal stability in phase change materials (PCMs) with data. Research has proven that Biochar demonstrates efficiency on par with state-of-the-art materials currently in use. However, the challenges of deploying this technology for scalability and their lifecycle impacts are discussed here. Finally, this paper argues how these combinations can be a catalyst in reaching the United Nations Sustainable Development Goals (SDGs) and shaping a green energy future.

The increasing ecological burden of petroleum-derived plastics has driven research toward sustainable alternatives like polyhydroxyalkanoates. However, high production costs limit their industrial implementation. This study investigates the use of agro-industrial wastes as alternative carbon sources for poly(3-hydroxybutyrate) (PHB) production by moderately halophilic Bacillus strains isolated from salted sheep skins. PHB content was quantitatively determined using the crotonic acid assay, and selected PHB samples were chemically characterized by GC-MS, FTIR, ¹H NMR and ¹³C NMR. Among three tested strains, Bacillus pumilus DB5 exhibited the highest PHB content, reaching 80.66 ± 1.5% of its cell dry weight when cultivated on olive mill wastewater (OMW). Remarkably, Bacillus pumilus DB5 maintained high PHB content (52.50 ± 1.08%) in non-sterile tap water, highlighting the potential of using non-sterile water conditions for PHB production. Subsequently, silver nanoparticles were incorporated into the PHB matrix to fabricate composite films. The antioxidant and antibacterial activities of the films were evaluated using the DPPH radical-scavenging assay and the JIS Z 2801–ISO 22196 method, respectively. The PHB film exhibited a DPPH radical-scavenging activity of 39.73 ± 0.75%, whereas the AgNP-PHB film showed 43.02 ± 1.20%. These films displayed antibacterial activity greater than 5-log₁₀ against both Escherichia coli and Staphylococcus aureus, with reductions of > 5.74 log₁₀ and > 5.52 log₁₀, respectively. This work demonstrates a promising strategy for valorizing agro-industrial wastes, particularly OMW, for PHB production and subsequent fabrication of AgNP-PHB composite films with antioxidant and antibacterial properties.

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The present study reports the recovery of lignin from combined pomegranate and banana peels through the process of valorisation with a binary deep eutectic solvent (DES) system comprising of choline chloride (CC) and oxalic acid (OA). The valorisation process was further optimized by Response Surface Methodology-based Central Composite Design, yielding an enhanced lignin recovery of 52.75 ± 0.55%. The interactions between the valorisation process variables and their effect on lignin recovery was analysed by developing a predictive quadratic model. Temperature and time had a profound influence on the valorisation process. The purity of the lignin was measured as 85.70 ± 1.62%. UV-Visible and Fourier Transform Infrared Spectroscopy confirmed the presence of the major functional groups of lignin. Field Emission Scanning Electron Microscopy images revealed agglomerated and spherical lignin structure; whereas X-Ray diffraction analysis identified its amorphous nature. Energy Dispersive X-ray Spectroscopy showed its higher and lower amounts of carbon and sulphur content compared to the commercially available lignin. ¹H Nuclear Magnetic Resonance Spectroscopy (NMR) depicted characteristic signals for methoxy, aliphatic, and aromatic protons of the lignin. The major interunit linkages of lignin along with their relative contents were identified by 2D Heteronuclear Single Quantum Coherence NMR spectra. The thermal stability of the lignin was confirmed by Differential Scanning Calorimetry measuring glass transition temperature of 88.75 ℃. The recovered lignin demonstrated higher antioxidant and antibacterial activities compared to commercial lignin. Overall, the RSM method was efficient in optimizing mixed fruit waste valorisation with CC-OA DES, resulting an enhanced lignin yield and purity.

Pyrolysis technology, as a biomass resource utilization technique, demonstrates broad application prospects due to its ability to efficiently convert biomass into high-value-added products such as biochar. However, current research has predominantly focused on single types of biomass feedstocks. This study proposes the hypothesis that the biochar production process via pyrolysis is primarily influenced by five organic components present in the biomass: cellulose, hemicellulose, lignin, protein, and lipids. Based on these organic components, this study investigated the thermal decomposition reaction mechanism of biochar preparation and constructed a general empirical mathematical model under low-temperature and slow heating conditions (300 °C, heating rate of 5 °C per minute, residence time of 150 min). The results indicate a high degree of consistency between the model’s predicted values and experimental data, with all parameters exhibiting an R² value exceeding 99%. By applying a response surface optimization method under specific constraint conditions, the optimal component ratios were determined to be: cellulose 11.4%, hemicellulose 13.1%, lignin 28.7%, protein 13.2%, and lipids 33.6%. In actual mixed experiments, the synergistic effect between protein and lignocellulose promoted the structural formation of the biochar, demonstrating that this component-based empirical framework provides a reliable predictive tool for producing biochar under target low-temperature, slow-pyrolysis conditions.