Search Results (1,365)

Tomato crop residues (TCR) from soilless greenhouses are treated as waste, causing greenhouse gas emissions and biomass loss. Within a circular economy framework, gasification converts TCR into renewable energy and biochar; however, its high pH and electrical conductivity (EC) limit its use as a substrate. This study evaluated whether pre-treatment could enable TCR biochar to act as a substrate component and nutrient source in tomato and pepper seedlings. Biochar was produced by gasification and pre-treated by water incubation plus nitric acid, reducing EC from 27 to 8.7 dS m⁻¹ and pH from 10.4 to 8.2 while achieving nitrate loading without leaching. Pristine biochar severely restricted growth. Subsequent experiments evaluated pre-treated biochar mixed with perlite or cocopeat, with or without external N and K. The 15/85% (w/w) pre-treated biochar/cocopeat mixture (PTB/C) showed the best overall performance. In the absence of additional N/K, PTB/C produced shoot biomass and shoot N concentrations comparable to N-/K-supplemented cocopeat; shoot K was comparable in tomato and higher in pepper. With N and K supplementation, PTB/C exceeded supplemented cocopeat biomass by 1.41- and 1.95-fold in tomato and pepper, respectively. These results indicate that pre-treated TCR biochar can reduce dependence on imported cocopeat and external N/K supply. Full article

Ergosterol (ERG) is a bioactive sterol found in fungal cell membranes with reported cholesterol-lowering, antioxidant, and antitumor properties. Supercritical Fluid Extraction (SFE) conditions were optimized for Lentinula edodes (shiitake) using Response Surface Methodology and subsequently applied to Pleurotus ostreatus (oyster). Optimized SFE (690 bar, 69.8 °C, no co-solvent) produced significantly more concentrated ERG extracts than Soxhlet extraction for both species—280.57 ± 10.80 mg_ERG/g_extract for shiitake and 95.87 ± 7.18 mg_ERG/g_extract for oyster—corresponding to a 107% and 65% increase, respectively. Three biomass pre-treatments—ultrasound, microwave, and enzymatic—were evaluated in combination with SFE. Enzymatic pre-treatment with chitinase significantly improved ERG concentration: 337.53 ± 23.12 mg_ERG/g_extract for shiitake. These results obtained after analysis of samples by GC-MS demonstrate that high-pressure SFE combined with chitinase pre-treatment is an effective strategy for producing ERG-rich extracts from fungal matrices. Full article

The mitigation of anthropogenic climate change caused by fossil fuel combustion is a critical global challenge that necessitates a transition to renewable energy systems. Bioethanol represents a major renewable fuel, but first-generation production relies on edible feedstocks, which raises concerns regarding food security. Consequently, research is shifting toward second-generation bioethanol produced from abundant non-edible lignocellulosic biomass sources. This review comprehensively examines the potential of Candida krusei (synonyms: Pichia kudriavzevii, Issatchenkia orientalis) to serve as an alternative biocatalyst for second-generation bioethanol production. Compared with the first-generation bioethanol-producing yeast Saccharomyces cerevisiae, C. krusei exhibits superior physiological traits, such as thermo, acid, and inhibitor tolerances, enabling the utilization of several lignocellulosic feedstocks. This review summarizes the taxonomic and physiological characteristics of C. krusei, describes case studies on bioethanol production, and discusses strategies for reducing production costs. Furthermore, the technical and biosafety challenges associated with the industrial deployment of C. krusei are critically examined, including xylose metabolism limitations, scale-up constraints, and the management of its opportunistic pathogenic nature. A life cycle assessment perspective suggests that the unique physiological properties of C. krusei contribute to reducing greenhouse gas emissions and energy consumption throughout the entire production process, from pretreatment to downstream ethanol recovery. Full article

Nowadays, approximately 50% of chemical surfactants come from petrochemical sources and pose environmental risks due to poor biodegradability, affecting microbial communities, aquatic organisms, and terrestrial ecosystems. Biosurfactants are eco-friendly alternatives, thanks to their strong surface tension-reducing activity, stability, low toxicity, and biodegradability, but their large-scale production is still limited by high costs and low yields. In this study, rice husk was evaluated as a renewable substrate from the agro-industrial field for lipopeptide production by the endophytic Bacillus subtilis AC7. Medium optimization through Plackett–Burman designs identified nitrogen sources and pH 6.5 as key factors enhancing biosurfactant production. Under optimized conditions, surfactin production increased from 4.2 mg/L in untreated rice husk to 266–276 mg/L with NaNO₃ and NH₄NO₃ supplementation, respectively. Combined laccase–amylolytic pretreatment further improved substrate utilization, enhancing sugar availability and supporting higher biomass and metabolic activity. In bench-scale fermentation, this condition yielded the highest surfactin concentration (237.5 mg/L). LC-MS/MS analysis confirmed surfactin as the main product, with C15 as the dominant homologue, in both shake-flask and bench-scale fermentations. These findings highlight a novel, sustainable process for surfactin production, offering a renewable alternative to synthetic surfactants while addressing both environmental and economic concerns. Full article

The sustainable management of agri-food waste is a key challenge in the context of the circular economy and energy transition. Anaerobic digestion is an effective method for converting organic waste into renewable energy; however, its efficiency is often limited by substrate properties, such as high lignin content, low biodegradability, and unfavorable C: N ratios. This study evaluates a low-energy pretreatment method based on a Vortex Layer Reactor (VLR, equivalent to the AVS-100 system) applied to slaughterhouse waste, swine manure, and spent mushroom substrate. The analysis included biogas yield, methane production, carbon conversion, process kinetics, and net energy efficiency. The results showed that pretreatment effectiveness depends on substrate type. No improvement was observed in slaughterhouse waste, with net energy efficiency decreasing by approximately 9%. In contrast, biogas yield increased by 14% for swine manure and 18% for spent mushroom substrate, with a maximum net energy gain of 17.6%. The process required only 2.16–3.6 kWh·Mg⁻¹ (about 9 kWh·Mg⁻¹ TS), significantly less than conventional methods. The findings indicate that pretreatment should be applied selectively, depending on substrate characteristics. This study supports decision-making in biogas plant management by integrating technological efficiency with energy and operational criteria. Full article

The replacement of synthetic dyes has gained increasing attention due to stricter regulatory policies and growing health concerns. Microbial carotenoids represent a promising alternative to artificial food colorants; however, their large-scale production is limited by the high cost of raw materials. In this context, the valorization of lignocellulosic biomass offers a strategy to develop low-cost substrates for microbial bioprocesses. Sotol bagasse (SB), an underutilized lignocellulosic residue generated during sotol production, was composed of 24% cellulose, 14% hemicellulose, and 42% lignin. A non-thermal plasma pretreatment, optimized through response surface methodology, achieved up to 29% of lignin removal. Subsequent enzymatic hydrolysis yielded a total sugar concentration of 28 g/L. The resulting hydrolysate supported the growth of Rhodotorula glutinis, yielding 4.4 g/L of biomass and 0.91 mg/L of carotenoids. To the best of our knowledge, this is the first report describing the use of non-thermal plasma as a pretreatment strategy for sotol bagasse, demonstrating its potential as a chemical-free approach for lignocellulosic valorization and sustainable microbial carotenoid production. Full article

This study assesses the aptitude of heterocystous cyanobacterial strain Dolichospermum spiroides MBDU 903 in integrated wastewater treatment and biofuel production at a laboratory scale. The efficiency of the strain was assessed based on pigment accumulation, growth kinetics, nutrient remediation efficiency, and biodiesel fuel quality. The results demonstrated that the biomass productivity of D. spiroides MBDU 903 ranged from 69.27 to 167.08 mg L⁻¹ day⁻¹ across various nutrient regimes, achieving a maximum lipid content of 31% (w/w). Cultivation in municipal wastewater with BG11+ (50% v/v) yielded the highest pigment production biomass. The physicochemical properties of the derived biodiesel were estimated from gas chromatography-derived fatty acid methyl ester (FAME) profiles. Furthermore, the biorefinery potential was explored as a proof-of-concept by fermenting the post-transesterification residual biomass with Saccharomyces cerevisiae, yielding 14.5 mg/g of bioethanol from the pretreated residue. While a 10 L pilot-scale trial was conducted, significant productivity drops suggest that further optimization is required to bridge the gap between laboratory results and practical application. This study provides a baseline evaluation of the dual-fuel potential of a heterocystous cyanobacterium under wastewater-integrated conditions. Full article

Bioethanol production from lignocellulosic biomass remains energy-intensive, and its energy performance can be affected by equipment degradation, utility disturbances, and operating variability. This study developed a degradation-aware mechanistic–AI framework for energy forecasting, anomaly detection, maintenance-oriented interpretation, and multi-objective optimization in bioethanol production under limited-data conditions. Reduced-order energy models were formulated for pretreatment, hydrolysis–fermentation, and ethanol purification. Equipment deterioration was represented through heat-transfer fouling, column-efficiency decline, and pump-efficiency decay. Condition-dependent modifiers were introduced to account for load-related degradation and intervention-related partial recovery. Benchmark-constrained synthetic time-series datasets were generated under baseline, accelerated-degradation, condition-dependent, stress, and data-quality perturbation scenarios. Empirical baselines and machine-learning models were compared for specific energy consumption prediction, with uncertainty reported using confidence intervals. The long short-term memory model achieved the lowest prediction errors under both baseline and stress conditions. Robustness testing showed that sensor drift, missing values, and outliers increased forecasting and anomaly-detection uncertainty. Sensitivity analysis identified degradation coefficients, seasonal disturbance, and anomaly-threshold selection as influential factors. Multi-objective optimization revealed trade-offs among specific energy consumption, ethanol purity, and equipment-health penalty. The proposed framework should be interpreted as a benchmarked methodological platform rather than a plant-validated maintenance or control system. Plant-specific deployment requires calibration with operating records, maintenance logs, cleaning records, and sensor-quality assessment. Full article

Flue gas torrefaction is an emerging biomass pretreatment technology that utilizes industrial flue gas as a reactive medium to replace inert atmospheres. However, the intrinsic complexity of biomass and the catalytic interference of ash hinder mechanistic elucidation. This study investigated the torrefaction behavior of demineralized poplar wood under N₂, CO₂, dry flue gas (DFG), and wet flue gas (WFG) at 300 °C for 5–20 min. Thermogravimetric analysis combined with kinetic modeling (FWO, KAS, and CR methods) revealed that the apparent activation energy (E_α) varied non-monotonically with atmosphere oxidizability. Under N₂, the average E_α was 177 kJ/mol following the three-dimensional diffusion model (D5). CO₂ gave the highest average E_α (314 kJ/mol) with the Avrami–Erofeev nucleation model (A₁/₄). DFG and WFG significantly reduced the average E_α to 133 and 128 kJ/mol, respectively, both following the A₁/₃ model. Consistently, WFG yields the lowest char and the highest gas yield. XPS and FTIR analyses indicated that flue gas atmospheres, especially WFG, promoted deeper deoxygenation and aromatization of biochar. Tar composition underwent a noticeable transition from ketones to aldehydes and saccharides under flue gas conditions, with the most remarkable variation observed under WFG. Gaseous products were dominated by CO₂ under N₂ and by CO under CO₂, while DFG and WFG produced moderate and stable gas compositions. These findings demonstrate that flue gas torrefaction, particularly under WFG, effectively enhances biomass effectively upgrades biomass quality by regulating pyrolysis kinetics and product distribution, and demineralized biomass is a suitable intermediate model for mechanistic investigation. Full article

The valorization of secondary biomass streams is an important step toward more resource-efficient biorefinery concepts and reduced dependence on fossil-based materials. In this study, agricultural and forest residues, namely Atlas cedar cones, mixed conifer cones, hazelnut shells, walnut shells, coffee silverskin, and cocoa shells, were investigated as feedstocks for producing colloidal lignin particles. Lignin-rich extracts were obtained by Organosolv pretreatment using 60 wt% aqueous ethanol, followed by particle formation through solvent shifting and purification by ultrafiltration. A particular novelty of this work is that highly different feedstocks were processed under identical Organosolv and solvent-shifting conditions, enabling a direct comparison of their suitability for colloidal lignin particle production within one consistent process route. The feedstocks differed markedly in extractive content and chemical profile, as shown by sequential Soxhlet extraction and qualitative GC-MS screening. Despite these differences in extract composition, solvent shifting yielded colloidal lignin particles with largely similar properties. Dynamic light scattering showed hydrodynamic diameters of 65–88 nm immediately after precipitation for all samples except cocoa shell, which formed strong agglomerates. The ultrafiltration step further introduced an industry-relevant downstream purification stage by removing most water-soluble low-molecular-weight compounds before product evaluation. After purification and redispersion, particle sizes ranged from 121 to 389 nm, indicating partial aggregation but overall successful recovery of stable colloidal dispersions. All purified particle suspensions exhibited comparable antioxidant activity in the FRAP (ferric reducing antioxidant power) assay, ranging from 12.3 to 18.4 mg lignin per mg ascorbic acid equivalents. These results demonstrate that even chemically diverse biomass side streams can be converted into purified colloidal lignin suspensions with similar colloidal behavior and functional performance. The findings highlight the potential of low-value agricultural and forest residues as promising raw materials for lignin-based antioxidant and material applications. Full article

The circular valorization of biomass for sustainable energy recovery is a strategic priority in the transition toward low-carbon systems. In the last decade, anaerobic digestion (AD) has emerged as an efficient technology to produce an energetic vector to replace natural gas with biomethane and reduce waste; however, the hydrolysis of refractory fractions remains the main rate-limiting step. This study investigates an innovative electro-assisted pretreatment of biomass to promote the first rate-limiting hydrolysis step of refractory compounds in biomethane production. Lignocellulosic residues are employed not only as feedstock for the AD process but also as substrates in electrohydrolysis (EH) pretreatment using an Ir-Ta mixed metal oxide (MMO) anode coupled with advanced biomass-derived carbon felt cathodes. Two cathodes were functionalized with Phragmites Australis (PhA) hydrochars, untreated (PA) and KOH-activated (PA-KOH), to enhance the in situ generation of reactive oxygen species (ROS). Brassica napus (Bn) was chosen as the other biomass selected as a feedstock of AD, and was subjected to EH at varying energy inputs (500–5000 kJ kg⁻¹), evaluating structural and biochemical shifts. The results demonstrate that EH effectively modifies the biomass matrix; the PA-KOH-CF cathode exhibited good selectivity to degrade lignocellulosic structures, but higher biomethane production was achieved at 2500 kJ·kg⁻¹ TS using PA-CF, reaching an increase of 52% compared with untreated samples. Kinetic analysis of the biomethane potential was performed using the modified Gompertz model. The model accurately captured the asymmetric sigmoidal transitions of methane production with different electrode configurations, and finally, energy balance assessment identified 2500 kJ·kg⁻¹ TS as the optimal operational threshold. These findings suggest that an excess of applied energy is critical to the availability of soluble organic matter and the presence of refractory compounds that reduce efficiency. This electro-assisted approach offers a robust strategy for intensifying AD, aligning with circular bioenergy objectives. Full article

The growing global demand for sustainable biotechnological routes for bioenergy production has paved the way for Brazil to position itself as a strategic leader due to its vast agricultural production and, consequently, agricultural residues, among which rice husk stands out. Although rice husk is widely used for energy cogeneration, its potential for producing high-value platform chemicals remains underexplored. This study aims to evaluate the production of value-added pyrolytic derivatives from rice husk by investigating the synergy between acid pretreatments and fast pyrolysis temperatures (350–600 °C). Thus, the experimental strategy involved intensifying the production of target compounds in the condensable fraction (bio-oil) from pyrolysis gases using different biomass pretreatments before fast pyrolysis according to the following conditions: (i) acid washing using acetic acid (10%), (ii) acid washing using nitric acid (0.1%) followed by impregnation using sulfuric acid (0.1–0.3%), and (iii) impregnation using sulfuric acid alone (0.1–0.3%). Fast pyrolysis was carried out over a temperature range of 350–600 °C using a pyroprobe microreactor coupled to a mass spectrometer (GC/MS). The best results, regarding overall volatile fraction, were observed when impregnation with 0.3% sulfuric acid was used prior to pyrolysis at 600 °C, resulting in around an 8.88-fold increase compared with untreated biomass. Nevertheless, the experimental conditions that favored the formation of our main chemical targets, such as levoglucosan, furfural and some phenols, were different. For instance, levoglucosan, furfural and eugenol increased by 21-, 10- and 22-fold, respectively, for biomass treated with HNO₃ (0.1%)/H₂SO₄ (0.2%) at 450 °C, whereas phenol and 4-vinylphenol increased by 35- and 14-fold at 500 °C. These findings can be considered satisfactory, highlighting the potential of the thermochemical conversion process as a valuable tool for the production of high-value chemicals from agricultural waste like rice husk. Full article

The potato chip processing (PCP) industry generates huge amounts of wastewater heavily polluted with organic matter and nutrients. The current treatment technology of PCP wastewater uses dissolved air flotation (DAF) and an activated sludge sequential batch reactor (SBR); both consume large amounts of chemicals and represent energy-intensive systems. This study explores the utilization of algae for the sustainable treatment of PCP wastewater, nutrient recovery, and algal biomass production. Conical flasks (1-L) and 6-L transparent plastic bottles were used as lab-scale algae photobioreactors (APBRs). Raw wastewater, an anaerobically pre-treated effluent and a DAF–SBR or shortly SBR effluent were used in the first, second, and third APBR. Three feed volumes from each source (150 mL, 300 mL, and 500 mL for first and second APBR and 400 mL, 600 mL, and 800 mL for third APBR) to a fixed volume of algal seed (200 mL) were tested to select the optimal feed volume and harvest time using a 1-L APBR. System performance and impact of water characteristics on quantity and quality of algal biomass were explored at pre-selected feed volume and harvest time in 6-L APBRs. All experiments were carried out in a growth chamber with continuous light (148.75 μmol.m⁻².S⁻¹). The results showed that 150 mL is the optimal feed volume for the first and second APBR at 10 days and 9 days growth cycles. An amount of 500 mL and 6 days were selected as the optimal feed volume and growth cycle for the third APBR. The average dry biomass yields at the pre-selected optimal conditions were 65.3 ± 11.4, 69.9 ± 12.0, and 100.6 ± 11.7 mg/L.d in the first, second, and third APBR, respectively. The first APBR achieved removals of 99.2 ± 0.4%, 98.7 ± 0.8%, 89.1 ± 4.3%, and 97.5 ± 1.4% for turbidity, COD, TKN, and TP, respectively, on average. Corresponding removal in the second APBR is 97.6 ± 2.6%, 91.6 ± 7.5%, 93.6 ± 4.5%, and 96.1 ± 1.4%, respectively, while the third APBR achieved 98.5%, 76.2%, and 97.0%, respectively. Additionally, the results of protein content and amino acids profiles indicate significant impacts of feed water quality on both parameters. The protein content was 30.64%, 32.53%, and 35.65% in the first, second, and third APBR, respectively. Similarly, the amino acids profile indicated a significant higher percentage of the amino acids in the third reactor compared with the first and second reactor. Full article

Lignin, the second most abundant polymer, remains largely underutilized, with nearly 90% of industrial lignin being combusted for energy due to its low phenolic hydroxyl content and structural heterogeneity of conventional extraction methods. The present study proposes a synergistic extraction method integrating sequential hydrothermal and twin-screw extrusion pretreatment followed by aqueous ethanol organosolv extraction. Three pretreatment strategies—hydrothermal pretreatment, twin-screw extrusion pretreatment, and sequential hydrothermal and twin-screw extrusion pretreatment—were compared. The sequential pretreatment exhibited the most favorable performance. Upon organosolv extraction, a lignin extraction rate of 67.9% was achieved, representing a 20.8% increase over that of the raw material. Extensive β-O-4′ bond cleavage during the integrated process liberated phenolic hydroxyl groups. This elevated the total phenolic hydroxyl content to 3.43 mmol·g⁻¹, representing a 63.3% increase relative to lignin derived from raw material. Concurrently, this bond cleavage yielded lignin with a narrower molecular weight distribution, indicating enhanced structural homogeneity. Additionally, cellulose retention after lignin extraction reached 88.9%. Mass-balance calculations indicated that 1000 g of raw material yielded 82.5 g of xylose and xylooligosaccharides, 148.2 g of highly active lignin, and cellulose-enriched solid residues, thereby facilitating the comprehensive utilization of the three primary components of lignocellulosic biomass. Full article

Herbaceous biomass is a promising renewable energy resource, but its use in thermochemical systems is often limited by severe fouling and ash agglomeration resulting from alkali-rich ash chemistry. This study directly compares two practical fouling mitigation strategies, kaolin addition and acid washing, for alkali-rich torrefied kenaf biomass under identical experimental conditions. The study quantitatively distinguishes aluminosilicate-based alkali stabilization from pretreatment-based alkali removal as two distinct pathways for controlling ash transformation. Kenaf exhibited severe ash agglomeration and contained high levels of K₂O (17.38 wt.%), CaO (31.52 wt.%), MgO (14.98 wt.%), SO₃ (9.43 wt.%), and P₂O₅ (6.90 wt.%). Kaolin addition progressively shifted the ash composition toward a SiO₂–Al₂O₃-rich system. From KA-10 to KA-30, SiO₂ increased from 22.86 to 33.58 wt.%, while Al₂O₃ increased from 7.65 to 15.43 wt.%. X-ray diffraction (XRD) analysis further showed that increasing kaolin addition suppressed alkali-salt phases and promoted the formation of aluminum-silicate phases. In contrast, acid washing directly reduced alkali species, decreasing K₂O to 5.66–7.83 wt.% and eliminating detectable Na₂O. The acid-washed samples were characterized by calcium-rich sulfate and silicate phases, indicating a distinct ash transformation pathway. Kaolin addition primarily reduced fouling by promoting aluminosilicate-based alkali stabilization, whereas acid washing reduced alkali–metal contents before thermal treatment. This distinction clarifies the different roles of additive-based and pretreatment-based strategies for fouling control in alkali-rich herbaceous biomass. Full article