Search Results (1,017)

This study presents a technical case study aimed at evaluating the emission performance and regulatory compliance of a low-level ethanol–gasoline blend (E5) produced from cocoa mucilage, applied in a spark-ignition vehicle applied in a spark-ignition vehicle without a catalytic converter, evaluated as a technical case study representative of aging fleet conditions. A controlled within-vehicle experimental design was employed to compare three fuels: Extra gasoline, Super gasoline, and an E5 blend (95% gasoline–5% bioethanol). Exhaust emissions carbon monoxide (CO), hydrocarbons (HC), carbon dioxide (CO₂), oxygen (O₂), and excess air ratio (λ) were quantified under standardized operating conditions (700 and 2500 rpm), following the Ecuadorian standard NTE INEN 2204:2017. Results demonstrate that the E5 blend improves combustion efficiency, reducing CO and HC emissions while increasing CO₂, indicating enhanced carbon oxidation. A systematic shift toward leaner combustion conditions (higher λ and O₂) was also observed, associated with the oxygenated nature of ethanol and improved air–fuel mixture homogeneity. However, regulatory assessment revealed only partial compliance, as all fuels met CO limits but exceeded thresholds for HC, λ, and O₂. Quantitatively, the E5 blend reduced CO emissions by approximately 10–15% compared to Extra gasoline and decreased HC emissions by approximately 15–25%, depending on the operating condition. Additionally, CO₂ emissions showed a slight increase, indicating improved combustion efficiency, while λ and O₂ values reflected a shift toward leaner combustion conditions. Overall, the findings highlight the dominant influence of vehicle mechanical condition on emission performance. Full article

Winter barley (Hordeum vulgare L.) is an important crop used for feed, food, malting, and bioethanol production. Recent research indicates that the seed mycobiome significantly influences seed health and usability, affecting its potential applications. This study examined the fungal species present in seven barley cultivars grown under two agrotechnical regimes. Fungal species were classified according to their effects on seeds and plants, and biodiversity indices were calculated for each group. Enhanced agrotechnical practices increased yields and improved grain quality. Higher DON concentrations were observed in low-yield treatments. Mycological analysis revealed that field fungi, particularly Fusarium, dominated the grain mycobiome and were associated with infection and reduced seed quality. High Dominance (Y), Margalef, and Shannon–Wiener indices for quality-deteriorating fungi correlated with lower yields, while the Dominance index (λ) for these fungi was negatively correlated with grain protein content. The prevalence of specific fungi on seeds depends on storage conditions and fungal adaptations, which may result in complementary consortia. Understanding these interactions can support the development of effective seed storage strategies and inform material classification and future use decisions. Full article

The integration of microalgal cultivation with wastewater streams offers a promising pathway to enhance resource efficiency within circular bioeconomy frameworks. However, the suitability of clarified aquaponics sedimentation effluent for producing carbohydrate-rich microalgal biomass remains insufficiently evaluated, particularly with respect to nutrient recovery and bioethanol-relevant feedstock potential. In this study, clarified aquaponics sedimentation effluent was assessed as a cultivation medium for Chlorella sp. under controlled laboratory conditions. Biomass productivity, nutrient removal performance, and carbohydrate accumulation were systematically evaluated and compared with conventional synthetic medium. Chlorella sp. cultivated in clarified aquaponic effluent achieved a maximum biomass concentration of approximately 2.05 g L⁻¹, exceeding that obtained in Bold’s Basal Medium. Carbohydrate content exceeded 40% of dry weight, indicating suitability for fermentable sugar production. Nitrate and phosphate removal efficiencies greater than 95% were achieved, with mass balance analysis confirming biological assimilation as the primary removal mechanism (~87.4%). This confirms the dual functionality of the system. The effective nutrient assimilation and confirmed the dual functionality of the system as both a biomass production and nutrient recovery process. Comparable performance under diluted and undiluted effluent conditions further indicated that freshwater dilution is not required following clarification. Light saturation was observed at 180–190 μmol m⁻² s⁻¹, providing guidance for energy-efficient operation. These findings demonstrate that clarified aquaponics effluent can serve as an effective alternative growth medium for producing carbohydrate-rich Chlorella sp. biomass while enabling nutrient recovery. The estimated bioethanol potential is theoretical, based on stoichiometric conversion assumptions, and experimental fermentation was not conducted. This work provides quantitative evidence supporting the integration of microalgae into aquaponic systems and establishes a foundation for future pilot-scale, techno-economic, and life-cycle assessments. Full article

Global energy demand relies heavily on fossil fuels, which produce greenhouse gas emissions. Additionally, municipal solid waste, driven by population growth, represents another source of emissions. In Mexico, organic waste contributes 61 million tons of CO₂eq annually due to inadequate disposal. In Mérida, Yucatan, over 231,000 tons of organic waste are generated yearly, including Urban Tree Pruning (UTP) from 760 public spaces—a significant, undervalued lignocellulosic resource. This study presents a comprehensive, year-round compositional characterization of Mérida’s UTP to establish its chemical profile and assess its seasonal stability as a precursor for bio-based products (i.e., bioethanol). Characterizing local and stable feedstocks, such as UTP, is a fundamental step to enabling Mexico’s compliance with biofuel policies like the 5.8% gasoline blend mandate (NOM-016-CRE) and the Alcohol-to-Jet strategy, supporting progress toward SDGs 7, 11, and 13. Based on a stratified random sampling, monthly analysis (May 2024–April 2025) revealed a consistent biochemical profile with mean annual contents of 23.32% lignin and 62.46% holocellulose. Statistical analysis (Tukey’s test) confirmed its structural homogeneity throughout the year. This uniformity is a key operational attribute, as it allows for the use of standardized industrial pretreatment parameters. Furthermore, the characterized composition supports a theoretical ethanol yield of 170 g/kg of dry biomass, a value competitive with traditional feedstocks like sugarcane bagasse. Consequently, Mérida’s UTP is characterized as a reliable and consistent biomass resource, supporting a transition from linear waste disposal to a circular bioeconomy model. Full article

This work performed a sensitivity analysis based on a conventional extractive distillation system to thoroughly evaluate the cost of separating bioethanol from water. The analysis considers the compositions and production volumes that are likely to result from the fermentation process of various biorefineries, regardless of their specific generation. It also outlines how the cost of bioethanol purification decreases as the ethanol concentration in the fermentation broth increases. For each composition-flow point in a gridded workspace, a distillation train was designed using the Aspen Plus^® simulation framework, focusing on minimizing the total annual cost. The results are discussed graphically, illustrating total annual costs and specific column costs in relation to feed stream composition and inflow. The findings quantitatively demonstrate that the cost of separation per mass unit of anhydrous ethanol decreases with higher inflow and increased input ethanol concentration. Additionally, it is evident that the primary cost is associated with the preconcentrator column. Full article

Forest waste is globally abundant and holds significant potential for valorisation in various sectors. This paper investigates its use in urban road infrastructures, utilising enzymatic lignin, a by-product from forest waste bioethanol production, as a bitumen extender for warm-mix asphalt. Since this asphalt concrete is produced at about 40 °C below the traditional hot-mix asphalt temperature, this study evaluates lignin’s ability to ensure the required mechanical performance of asphalt concrete in both aged and non-aged states. The TEAGE—TEcnico accelerated AGEing device—applied UV radiation and wet/dry cycles to virgin bitumen, a lignin blend, and compacted asphalt concrete specimens to replicate urban weathering. Cylindrical specimens underwent indirect tensile tests to assess water sensitivity, while beam samples underwent four-point bending tests to evaluate stiffness and fatigue resistance. The results indicate that this warm-mix asphalt, with lower atmospheric emissions during manufacturing and pavement construction, meets the mechanical demands of urban roads, particularly with respect to fatigue and water resistance. However, the findings also show that asphalt concrete containing lignin experiences excessive ageing of small specimens, and further testing on compacted slabs is needed to better simulate exposure to UV radiation in pavement layers. Overall, the study concludes that lignin lowers asphalt production temperatures and partially substitutes conventional binders, with promising applications in urban pavement technologies. Full article

Date palm (Phoenix dactylifera L.) by-products from bioethanol production represent an underutilized resource rich in bioactive molecules. This study aims to their valorization through characterization of polysaccharides and phenolic compounds from the Medjool variety, both before and after yeast fermentation for bioethanol production. Three sequential types of by-products were analyzed—Ext1 (post hot-extraction), Ext2 (post fermentation), and Ext3 (post distillation)—and compared with Dat-Me. High Performance Liquid Chromatograp-Diode Array Detector-Mass Spectrometry (HPLC-DAD-MS) analysis allowed identifying 22 phenolic compounds, primarily cinnamic acid derivatives and glycosylated flavones such as luteolin and chrysoeriol. Fermentation increased total phenolic content from dry weight, while leading to an improved polysaccharide recovery (i.e., from 14.2% to 42.1% dry weight). Two polysaccharide fractions (F1 and F2) were isolated and characterized by ¹H-NMR and Dynamic Light Scattering (DLS). F1 is a pectic polysaccharide, with a galacturonic acid content ranging from 24.2% (Ext3) to 52.2% (Dat-Me), a degree of methylation (DM) between 34.4 and 50.6%, and a degree of acetylation (DA) of 23.6–42.2%. F2 consists of a non-pectic polysaccharide, characterized by a low galacturonic acid content (5.6–6.8%) and a DM of 12.6–47.1%, but it is highly acetylated, with a DA ranging from 90.1 to 93.3%. DLS analysis confirmed fermentation-induced depolymerization, with molecular weights ranging from 6.6 × 10⁴ to 8.5 × 10⁵ KDa for both the fractions. Overall, Medjool date by-products obtained after bioethanol production represent a sustainable source of high-value phenolic antioxidants and polysaccharides with different structures suitable for future applications in food, pharmaceutical, and cosmetic formulations. Full article

To establish a biorefinery within kraft-pulp mills, the extraction of fermentable sugars must be balanced with the preservation of fiber quality for papermaking. This study investigates this trade-off by applying partial enzymatic hydrolysis to unbleached high-kappa eucalyptus kraft pulp to co-produce bioethanol and packaging-grade materials. Although the mass-transfer limitations inherent to the high-consistency strategy (15% solids or 150 g L⁻¹) restrict extensive saccharification (keeping glucose conversion below 5% at 1.5 h), it naturally directs the process toward a low-severity regime essential for fiber conservation. Structural analysis (X-ray diffraction and microscopy) revealed that enzymes preferentially targeted amorphous regions, increasing crystallinity (from ≈74% to ≈82%) but reducing intrinsic fiber strength (tear) over time (dropping from ~5.6 to ~2.3 mN·m²·g⁻¹ within 30 min). However, a strategic window for valorization has been identified. Instead of direct papermaking, hydrolyzed residue is highly effective as a strength-enhancing additive. When blended (20% w w⁻¹) with commercial pulp, the modified fibers improved interfiber bonding, restored the tensile strength, and significantly increased the Burst Index (up to ~1.7 kPa·m²·g⁻¹). These results demonstrate a viable industrial approach using partial hydrolysis to recover hemicellulose-based sugars for biofuels, while transforming the solid fraction into a high-performance reinforcement agent for paper packaging. This approach effectively converts a potential trade-off into a synergistic dual-product stream. Full article

Ammoniacal nitrogen (NH₃-N) is a major pollutant in municipal, industrial, and agricultural wastewaters and is a key driver of eutrophication and aquatic ecosystem degradation. This review paper assessed the potential of water hyacinth (Eichhornia crassipes) as a sustainable phytoremediation option for removing ammoniacal nitrogen from wastewater. This paper focused on the plant’s biological characteristics, nutrient uptake pathways, and adaptability to varying environmental conditions. Specific mechanisms examined include direct root uptake of ammonium, internal translocation, and microbial-assisted nitrification and denitrification within the rhizosphere. The influence of pH, temperature, salinity, retention time, and plant density on removal efficiency was also assessed in this study. Across laboratory, pilot, and field-scale studies, water hyacinth achieved ammoniacal nitrogen removal efficiencies ranging from 74% to 97% under favorable conditions, alongside significant reductions in biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS). Integration with constructed wetlands, microbial systems, and hybrid treatment approaches further enhanced nitrogen removal and process stability. This paper also highlighted opportunities for biomass valorization through biogas, bioethanol, and compost production while identifying challenges related to salinity sensitivity and biomass management. Overall, water hyacinth emerges as a cost-effective, nature-based solution for decentralized wastewater treatment, with strong potential to support sustainable water management and circular bioeconomy initiatives. Full article

Sexual reproduction in yeasts is a fundamental biological process that promotes genetic recombination and phenotypic diversification, enabling adaptation to fluctuating and stressful environments. Sporulation and subsequent mating generate novel allele combinations that enhance evolutionary potential; however, many domesticated industrial strains exhibit reduced sporulation capacity, limiting their use in breeding programs and constraining the generation of new diversity. This represents one of the major bottlenecks for improving yeast performance in industrial fermentations, particularly under the harsh conditions characteristic of bioethanol production. In this study, we exploited meiotic recombination and mass-mating strategies to expand genetic and phenotypic diversity in S. cerevisiae. By mass-mating haploid spores derived from genetically distinct parental strains, we generated highly heterogeneous hybrid populations in a single step, overcoming the limitations imposed by conventional breeding approaches, such as micromanipulation. These populations were subsequently screened to identify strains with enhanced fermentative performance and increased tolerance to industrial stressor media associated with bioethanol production. Our results demonstrate that sexual reproduction combined with mass-mating represents an efficient strategy to unlock hidden genetic potential and generate superior industrial yeast phenotypes. This work highlights the value of utilizing the natural reproductive biology of S. cerevisiae to accelerate strain improvement and develop robust yeasts adapted to challenging fermentation environments. Full article

Macroalgae represent a promising third-generation feedstock for biorefinery due to their high biomass productivity and non-reliance on arable land. However, their complex cell wall structure poses a significant barrier to efficient bioconversion. This review integrates current pretreatment methods, including physical, chemical, biological, and combined approaches, with a focus on their mechanisms, effectiveness, and limitations. Furthermore, it explores the conversion of pretreated macroalgal biomass into bioenergy and biochemicals, such as bioethanol, organic acid and polyhydroxyalkanoate, via microbial fermentation. The review also examines the application of genetic editing tools (e.g., CRISPR-Cas systems) for the targeted modification of macroalgae to improve their inherent characteristics for biorefinery, such as reducing biomass recalcitrance or increasing the content of target carbohydrates. Finally, future perspectives on technological innovations and integrated industrial chains of macroalgal biorefinery are discussed. This review serves as a systematic reference for deepening the understanding of macroalgal cell wall deconstruction processes and supports the development of efficient and environmentally benign pretreatment strategies to advance macroalgal biorefinery toward industrialization. Full article

Bio-CO₂ is part of the natural carbon cycle and represents a sustainable carbon source for the production of Renewable Fuels of Non-Biological Origin (RFNBOs), such as synthetic methanol. This study addresses the critical knowledge gap in aligning diverse biogenic CO₂ sources with e-methanol requirements in the EU by providing harmonized mapping, based on datasets, literature sources, and reported industrial statistics at the sectoral and country level. Bio-CO₂ streams from biogas and biogas upgrading, biomass combustion, pulp and paper, bioethanol production, and the food and beverage sector are evaluated for total emissions, CO₂ concentrations and purity, the geographical distribution, seasonality, and impurity profiles. Results show that approximately 350 Mtpa of bio-CO₂ are emitted across the EU, with highly heterogeneous characteristics. Biogas upgrading and fermentation-based processes generate highly pure CO₂ streams (>98–99%), yet their small and dispersed nature complicates logistics. In contrast, biomass-combustion and pulp and paper sectors provide large volumes (around 214.6–298.2 Mtpa and 73.9 Mtpa CO₂, respectively), but in diluted streams (typically 3–15% and 10–20%). Replacing just 10% of the EU maritime fuel demand with e-methanol would require 53.6 Mtpa of bio-CO₂ and 58 GW of electrolyzer capacity, a stark contrast to the current operational 385 MW. The findings highlight the need for infrastructure planning and aggregation hubs to enable the large-scale deployment of RFNBO methanol in the maritime sector. Full article

To achieve the goal of the 2015 Paris Agreement to limit global warming to 2 °C compared to pre-industrial levels, South Korea is implementing a policy to use bioethanol as a transportation fuel based on the Renewable Fuel Standard (RFS). This study proposes a mixed-integer linear programming (MILP) model to design an optimal bioethanol supply chain utilizing rice straw, a readily available resource in South Korea. To minimize the total cost of bioethanol production, the proposed model considers optimal facility locations, i.e., those of feedstock collection (farm), refining (refinery), and consumption (market), and transportation volumes. This experiment is conducted to evaluate the blending ratios of bioethanol in gasoline (3%, 6%, and 9%) specified by the Renewable Fuel Standard (RFS) policy, based on actual gasoline consumption data in South Korea. In the RFS 3% scenario, operating a single large-scale refinery was the most economical option, but in the RFS 6% and RFS 9% scenarios, multiple refineries must be utilized to ensure supply chain economics. In conclusion, the proposed MILP model shows the practicality of gradually increasing the number of refineries and selecting the optimal location for each region as future bioethanol demand increases. Full article

The conversion of lignocellulosic biomass (LCB) into biofuels is hindered by its inherent resistance and the drawbacks of conventional pretreatment, which include high cost, intensive energy use, and inhibitor formation. Here, we present a novel, one-pot bioconversion process that bypasses pretreatment by integrating cerium-doped iron oxide nanoparticles (CeFeO₄NPs) with a specialized enzyme system. The system utilizes enzyme supernatant from Penicillium janthinellum mutant EU-30, a strain developed via chemical–physical mutagenesis, which exhibits stable hemicellulase activity and a 25–30% increase in cellulase activity. The integrated approach effectively saccharified raw sugarcane bagasse (SB) within 24 h, generating the highest yields of 12.8 ± 0.5 g/L glucose and 11.54 ± 0.5 g/L xylose compared to other substrates tested. Subsequent fermentation with Saccharomyces cerevisiae yielded 13.47 g/L ethanol (1.21 g/L/h productivity) and demonstrated concurrent consumption of both hexose and pentose sugars. We propose that residual CeFe₃O₄NPs in the hydrolysate mitigate carbon catabolite inhibition, thereby increasing xylose utilization. This was attributed to the residual CeFe₃O₄NPs in the hydrolysate, which are thought to upregulate xylose-metabolism-related genes in S. cerevisiae, thereby alleviating carbon catabolite inhibition. This method offers a streamlined, economical, and sustainable platform for producing carbon-neutral bioethanol from agricultural waste, eliminating costly pretreatment and simplifying downstream processing. Full article

This work presents an integrated Python-based framework to optimize the ethanol-to-1,3-butadiene conversion over a K₂O:ZrO₂:ZnO/MgO–SiO₂ catalyst, a sustainable alternative in decarbonizing plastics and rubber manufacturing. Thermodynamic evaluations confirmed the feasibility of all elementary steps, while kinetic modeling identified the butadiene-forming reaction as the most sensitive step. Experimental data were analyzed using multivariate surface-response methods, revealing an optimal operating window of 350–375 °C and 0.93–1.24 h⁻¹. A Random Forest model (R² = 0.91) ranked weight hourly space velocity (WHSV) and selectivity descriptors as the most dominant variables, providing a quantitative basis for data-driven process intensification. Full article