BioEnergy Research最新文献

Turning biomass waste into briquettes using densification techniques is one of the most promising steps toward mitigating biomass waste pollution and fuel issues in developing countries. Despite the continuous growth of scientific output over the past few decades, only a limited amount of information is available in the literature on biomass briquette optimization and mathematical modeling, as well as the physiochemical characterization of biomass feedstocks and briquette operating variables. In light of this gap in the current literature, this study summarizes the current state of the art and recent advances in biomass-based briquettes generated from agro-residues as an alternative source of clean energy. The primary research method for this study is literature review and conceptual modeling. First, many densification processes, such as piston press, screw press, roller press, hydraulic press, and quality variables such as ash content, calorific value, moisture content, density, compressive strength, shatter index, etc., are thoroughly discussed and compared. Then characteristics of different biomass wastes are studied, together with process parameters, including temperature, type of binder used, particle size, and influence on densification process choice. The current evaluation concentrated on the mathematical modeling and optimization of the briquetting technology and the usefulness of briquettes in applications for heating, cooking, and energy production. Overall, this manuscript will help new researchers understand the basic methodology, classification, limitations, and future perspective of briquetting technology in the production of solid biofuels.

The current study examines the phycoremediation potential cum biomass productivity and biomass quality of hitherto uninvestigated five algae in Bold’s Basal Medium (BBM) of varying nitrogen (½ to 4 × N), phosphorus (½ to 4 × P), and both together (½ to 2 × NP) with varying N:P. All five algae displayed unique responses in biomass productivity, lipid yield and productivity, and nitrogen (N) and phosphorous (P) removal efficiency. Chlorolobion braunii exhibited the highest biomass productivity (107 to 109.23 mg/L/ day) in N-rich media (3 to 4 × N in BBM), and Monoraphidium contortum exhibited the highest biomass productivity (103.66 mg/L/day) in P-rich media (2 to 4 × P in BBM). All the algae exhibited a higher lipid yield and productivity in BBM with a reduced ratio of N:P (0.85 to 1.47) from a lesser addition of N (½ × N or NP in BBM). Monoraphidium contortum exhibited significantly higher lipid yield (44.38%) and productivity (35.94 mg/L/day) than other species. The lipid content of four species demonstrated high-quality biofuel properties. Halochlorella rubescens exhibited the maximum nitrogen removal efficiency of 96% (in BBM), and Monoraphidium contortum exhibited the maximum phosphorus removal efficiency of 94.4% (2 × NP in BBM). Overall, the experiments stand as a model for understanding the influence of variations in N and P concerning N:P on biomass productivity, lipid content, lipid productivity, and N and P removal rate and efficiency of algae for initial standardization of the culture protocols for further industrial trials.

Abstract

This study investigates the gasification of cellulose, lignin, corn stover (rich in cellulose) and walnut shells (rich in lignin) using CaO as a catalyst. The objective was to understand the effect of the different biomass components on the gasification products and the performance of the CaO catalyst. Notable results indicate distinctive product distribution: cellulose yields higher liquid (58%) and CO (95.36%) products, while lignin produces increased H₂ (47.88%), CH₄ (34.34%), and CO₂ (29.58%). Gasification of biomass feedstocks, corn stover (cellulose-rich) and walnut shell (lignin-rich), aligns with pure cellulose and lignin trends. Catalyst characterization highlights that cellulose exhibits a greater tendency for coke formation, leading to elevated tar compounds and coke deposition on the catalyst surface. The solid residue from cellulose gasification displays a smaller pore volume (5.70 m²/g) and specific surface area, indicating undesirable catalyst rearrangement. XRD analysis indicates a higher carbonation rate of CaO in lignin-rich gasification, leading to increased CaCO₃ formation. Further results show a higher CO₂ concentration (3.35 mol/kg) and lower CO production (0.54 mol/kg) in corn stover gasification, contrasting with walnut shell (CO₂: 14.24 mol/kg, CO: 1.24 mol/kg). The study underscores the quantitative assessment of biomass composition for optimizing gasification processes, vital for catalyst selection and ensuring efficient CO₂ capture in industrial applications.

This a two-part study was conducted to improve the enzymatic saccharification of apple pomace (AP) by pretreatment and fed-batch enzymatic hydrolysis. The impact on the enzymatic hydrolysis and structural characterization in AP of four pretreatment processes, sodium hydroxide (SH), ethanol (ETH), liquid hot water (LHW), and Phanerochaete chrysosporium (PC), were evaluated. In addition, the enzymatic hydrolysis efficiency of AP at high solids content was improved by optimizing the enzyme hydrolysis conditions and using fed-batch strategy. The results demonstrated that both ETH 160 °C and PC pretreatments effectively enhanced the efficiency of enzymatic saccharification in AP while disrupting its compact structure. Notably, PC solid-state fermentation for 7 d proved to be a mild yet effective pretreatment method for AP. By utilizing PC pretreated residue at a substrate content of 20% (w/v) with an addition of 5 mg/g pectinase and 50 mg/g Tween 80, along with employing fed-batch enzymatic hydrolysis, the total sugar concentration increased by 30.3% after 72 h. At this point, the highest total sugar concentration reached 77.5 g/L with an enzymatic hydrolysis yield reaching 73% (glucose). This study presents not only the first application of PC as a pretreatment method for AP but also establishes a new enzymatic process with high solids content to provide a new strategy for AP resource utilization.

Two α-arabinofuranosidases from the fungus Chrysoporthe cubensis COAD 3356 were partially purified, identified, characterized, and applied to the sugarcane bagasse saccharification to evaluate the potential of these enzymes to increase the sugar production from lignocellulosic biomass. The α-arabinofuranosidases were classified on GH51 (α-Ara1) and GH54/CBM42 (α-Ara2) families. After sugarcane bagasse saccharification, using the commercial cellulase-rich cocktail supplemented with α-Ara2 (15 U/g), there was an increase of 1.6, 3.9, and 6.1 times in the release of glucose, xylose, and arabinose, respectively. On the other hand, there was no increase in sugar release with α-Ara1 supplementation under the same saccharification conditions. The enzymes presented maximum activity at pH 4.0, and 60 °C. Both α-Ara1 and α-Ara2 were thermostable at 50 °C, presenting half-life values of 68 and 77 h, respectively. The enzyme α-Ara2 presented higher K_Mapp for synthetic substrate ρNP-α-arabinofuranoside (1.38 mmol/L) and wheat arabinoxylan (1.28 mmol/L) when compared with α-Ara1. A new fungal α-arabinofuranosidase structure, still little described in the GH51 family, was predicted. Furthermore, the results indicated that α-Ara2 is a promising molecule to be used to supplement cocktails for lignocellulose degradation.

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The scarcity of essential minerals in the wort used for bioethanol production has long been a persistent concern in industrial processes. This scarcity can negatively impact various aspects of production, including yeast cell vitality and sugar-to-ethanol conversion. In this study, we assessed the nutritional profile of key components of the industrial bioethanol production process and identified nitrogen, phosphorus, magnesium, manganese, zinc, and copper ions deficiencies. Supplementation of fermentation assays with ^TMNitrofós was carried out until reaching the maximum allowed for manganese (24.5%), zinc (49.4%), and copper (8.8%). Laboratory-scale fermentation assays were conducted under varying conditions of soluble solids in the wort (20, 24, and 26°Brix). These experiments aimed to assess the primary productivity parameters in response to the application of ^TMNitrofós. Results showed that fermentations using wort with 24 and 26°Brix supplemented with ^TMNitrofós led to 7% higher fermentative efficiency compared to the control group. The supplemented fermentations demonstrated higher levels of cellular vitality (76.6%) compared to the control group (55.3%). Considering a scale-up in the bioethanol production process with ^TMNitrofós supplementation, an increase of 266 m³ of ethanol per month was achieved compared to the control group, resulting in cost savings of R$ 586,879.20.

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Abstract

To reduce the C footprint of human activities, there is a growing need for alternative energy sources including the production of bioenergy feedstocks. Miscanthus × giganteus is a high yielding grass with low environmental impact and high potential for feedstock use. Studying the composition of the aboveground tissues of Miscanthus is important for understanding feedstock quality for biofuel conversion and how crop residue quality may affect soil input management. Data on Miscanthus leaf and stem chemistry including carbon (C), nitrogen (N), macronutrient concentrations, and the optical characteristics of the water extractable organic matter (WEOM) was analyzed to identify differences in composition between aboveground tissues and modeled to identify soil variables that may be correlated with tissue chemistry. Leaves and stems were dominated by N, potassium (K), calcium (Ca), phosphorus (P), and magnesium (Mg), but overall, the leaves contained higher nutrient concentrations compared to the stems. The leaves displayed elevated Si:K (0.0935) and Ca:K (0.445) ratios and lower C:N (36) and C:P (323) ratios compared to the stems (0.0560, 0.145, 150, and 645, respectively). Leaf WEOM contained large, aromatic, and complex structures, while the stem WEOM was dominated by small, recently produced structures. Varying relationships were found between tissue C and the mobile C pool in surface (0–15 cm) and deep (45–60 cm) soils. Overall, Miscanthus leaves had a chemical composition indicative of reduced biofuel quality compared to the stems. The relationships with soil mobile C suggest a dynamic linkage between Miscanthus physiology and this active soil C pool. These results have implications for crop nutrient allocation and nutrient management practices.

The waste generated by the mezcal and seafood restaurant industries has significant negative environmental impacts on soils, water, and air. However, these waste materials offer the potential for methane production through anaerobic digestion. This research focuses on evaluating a methodological strategy that involves using an enriched inoculum, co-digesting waste materials, and applying specific pretreatment (chemical, thermal, and adjusting the volumetric ratio of residues) to produce biogas with a high methane content, as assessed through the Biochemical Methane Potential (BMP) test. The results demonstrate that the enriched inoculum used in the test exhibited a pH of 8.18, an Alkalinity of 31 g CaCO₃/L, and an alpha (α) ratio of 0.75. The BMP test was conducted over 29 days. In the most successful test, which involved pretreatment at a temperature of 50 °C, a residue ratio of 1 V_SW (Volume of Seafood Waste)/2 V_MV (Volume of Mezcal Vinasses), and a pH of 6.5, we achieved a methane production of 1420.51 ± 0.038 N mL CH₄, with a biogas containing 81.5% methane. This process also yielded 175.37 N mL CH₄ per gram of Volatile Solids (VS) and a degradation kinetic constant of 0.14 1/d. Through the methodological strategy used with the combination of an enriched and stabilized inoculum, the co-digestion of the waste for nutrient complementation, and the application of pretreatments, it was achieved that the different stages that constitute the anaerobic process allowed for the establishment of optimal conditions for the generation of biogas with a high methane content.

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Abstract

The main objective of this study was to develop a citric acid-catalyzed hydrothermal pretreatment to reach the maximum sugar recovery from soybean hull (SH), in the context of a biorefi nery concept. A central composite design (CCD) was used to optimize pretreatment conditions through the analysis of citric acid concentration, time, and temperature effects. Optimized conditions were defined as 3.56% w/w, 46.1 min, and 135.7 °C. From the solid fraction, 99.5% and 83.0% of glucose and xylose conversion, respectively, were obtained after enzymatic hydrolysis. Sugars were fermented successfully to L-lactic acid by Lactobacillus pentosus. In fact, SH hydrolysate presented no trace of inhibitor compounds, and glucose was totally consumed during fermentation. After 24 h of fermentation, a conversion rate of 0.724 g/g of sugars to lactic acid and 80.5% of the stoichiometric theoretical yield were reached. In addition, from the liquid fraction, 47.8 mg/g of xylooligosaccharides (XOS) was produced. This work demonstrates the potential of SH to be exploited as feedstock, with mild and efficient pretreatment process, for medium- to high-value bioproducts production in biorefineries.

The current study investigated the methane generation potential from the anaerobic bio-digestion of fruits and vegetables wastes (FVW) generated in a food supply center in Brazil. This study used the ensiling process as a pre-treatment for this lignocellulosic biomass aiming to improve the methane yield. FVW were mixed in the same proportion (0.2 g on a volatile solid basis per residue) and ensiled at room temperature (≈25 °C) for 30 and 55 days (samples Ensil-30 and Ensil-55). The ensiled and untreated waste samples were inoculated with industrial granular sludge and incubated at 37 °C (mesophilic conditions) until there was no more significant biogas generation. The experimental data were fitted to the First-order, Cone, and Modified Gompertz kinetic models. The methane yield of the ensiled samples was ≈21% higher than the methane yield of the untreated sample. Considering the ensiled samples, the methane generation was statistically the same (52.0 and 51.3 NmL/gvs for samples Ensil-30 and Ensil-55, respectively), that is, duplication of the storage period failed to increase the methane volume. Although the results indicated that the ensiling of FVW could be a viable strategy to improve the biodegradability of the lignocellulosic biomass and promote its valorization as an energy source, a preselection of the agricultural residues that will feed the biodigesters is suggested. Considering the process conditions and the residues used, the substrate characteristics were shown to carry out a key role in the bio-digestion processes and consequently in methane generation.