BioEnergy Research最新文献

The economic competitiveness of 2G-bioethanol technology should improve through the improvement of the sugar release and the valorization of by-products, especially lignin. Thus, an integrated scheme with corncob was developed to produce ethanol using low dosages of cellulases and value-added products from the semi-simultaneous saccharification and fermentation (SSSF) residue. Enzymatic hydrolysis and SSSF of acid pretreated corncob (< 20 mesh and > 20 mesh) were carried out under cellulase dosages of 5, 10, and 15 FPU/g in the absence and presence of polyethylene glycol 1500 (PEG 1500). The SSSF residue was used to obtain lignosulfonate via sulfomethylation reaction and phenolic acids via alkaline hydrolysis using 4% (w/v) sodium hydroxide and 0–5% (v/v) hydrogen peroxide. Pretreated corncob < 20 mesh allowed the reduction of cellulase dosage to 5 FPU/g without compromising sugar release. The addition of PEG 1500 boosted sugar release, reaching 56.73 g/L glucose under 20% (w/v) solids. The maximum ethanol production of 31.64 g/L was obtained using 5 FPU/g cellulases, 2% (w/w) PEG 1500, and 20% (w/v) solids (gradual addition). FTIR confirmed the preparation of lignosulfonate from SSSF residue, and the surfactant showed good stabilization performance in oil/water systems (emulsification index≈30%). High yields of p-coumaric acid (8045.3 mg/100 g) and ferulic acid (1429.4 mg/100 g) were obtained in alkaline hydrolysis with 5% (v/v) hydrogen peroxide. Based on these findings, corncob is versatile and can create a biorefinery with high economic potential.

The present study aims to investigate the potential for producing an aromatic hydrocarbon-enriched fuel from Scenedesmus sp. microalgae using low-cost zeolite in catalytic flash pyrolysis. The methodology adopted in this study involved the use of an analytical micropyrolyzer coupled with a gas chromatograph/mass spectrometer at 500 ºC to assess the effectiveness of the low-cost HZSM − 5 catalyst in deoxygenation, denitrogenation, and aromatization activities of volatile reaction products. The HZSM − 5 catalyst was synthesized using the hydrothermal method, employing low-cost precursor materials, rice husk ash, and diatomite residue as alternative silicon and aluminum sources. The oxygenated and nitrogenated volatile products in non-catalytic flash pyrolysis constituted 51.7% and 15.3%, respectively. Catalytic upgrading of pyrolysis vapors from Scenedesmus sp. microalgae was demonstrated by significant deoxygenation and denitrogenation activity, reaching up to 99%, while chemical industry-relevant classes experienced increased proportions: aromatic hydrocarbons by 5.8-fold, and aliphatic hydrocarbons by 1.7-fold. Around 78% selectivity for aromatic hydrocarbons was achieved, predominantly yielding BTEX (benzene, toluene, ethylbenzene, and xylene). Another significant finding is that 89.8% of the renewable hydrocarbons produced fall within the gasoline range (C₅ − C₁₂). This study conclusively indicates that the low-cost HZSM − 5 catalyst shows significant promise for producing high-quality bio-oil through the flash pyrolysis of Scenedesmus sp. microalgae.

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Hydrogen, volatile fatty acids (VFAs), and methane coproduction from sweet sorghum stems using bacterial consortium was investigated as an efficient and sustainable pre-treatment strategy to improve energy recovery. Integrated two-stage dark fermentation and methanization approach aimed to reduce fractionation, juice extraction, and pre-treatment steps to improve the efficiency and sustainability of stalks energy bioconversion. Stems biomass loading did not significantly influence hydrogen and VFAs productivities. Energy recovery yields were (7.07) and (10.01) MJ/kg dry matter (DM), respectively, for raw stem single dark fermentation (DF) and methanization processes, corresponding to 41.22% and 58.37% of raw stalk energy potential. Methanogenic potential increase of 31.9% and energy bioconversion yield of 13.21 MJ/kg DM were reached for solid residues from DF (80.75% of their energy content), suggesting that bacterial consortium efficiently pre-treated sorghum stalk fibers. Coupling process led to 88.74% net biomass energy recovery yield, corresponding respectively to 57.38% and 40.23% more than single DF and methanization. Fiber degradation ability of DF bacterial consortium significantly contributed to improve sorghum stalk energy recovery efficiency and cost-competitiveness.

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Degenerate strains of Clostridium acetobutylicum lack the ability to produce solvents and sporulate and remain in a permanent acidogenic state, allowing continuous hydrogen and organic acid production through anaerobic fermentation. Eichhornia crassipes, an invasive aquatic plant, emerges as a promising source of fermentable sugars for hydrogen production via anaerobic fermentation. In this study, a degenerated strain of Clostridium acetobutylicum was isolated and subsequently cultivated in the presence of a hydrolysate solution obtained from the alkaline pre-treatment and enzymatic hydrolysis of Eichhornia crassipes. The hydrolysate was mixed with a defined medium and served the dual purpose of providing essential nutrients and mitigating inhibitors, eliminating the need for an additional detoxification step. A pure defined culture medium served as a control. The extraction methods employed led to the release of low concentrations of inhibitors, reaching 0.1 g/L of furfural and 0.18 g/L of HMF. Kinetic characterization revealed that in the presence of Eichhornia crassipes hydrolysate, the degenerate strain exhibited lower specific growth rates ranging from 0.114 to 0.156 h⁻¹, compared with the control medium which ranged from 0.131 to 0.179 h⁻¹. This was accompanied by lower yields, ranging from 0.115 to 0.167 g_DCW/g in the presence of hydrolysate versus 0.178 to 0.190 g_DCW/g in the control medium, and diminished butyric acid production of 1.318 to 2.932 g/L in the presence of hydrolysate versus 1.749 to 3.471 g/L in control cultures. Despite reduced growth, high biohydrogen volumetric productivity was achieved, reaching 7.3 L/L·d, along with a significant yield of 2.642 mol of hydrogen per mole of glucose consumed. This represents 66.05% of the maximum stoichiometric yield calculated when acetic acid is the sole byproduct. Apparently, the presence of low concentrations of furfural and HMF released during the pre-treatment of Eichhornia crassipes not only negatively affects growth capacity but also diminishes butyric acid production, favoring biohydrogen production.

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.

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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