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The potential of native as well as acid/alkali pre-treated paddy straw was investigated as inducer substrate for Aspergillus terreus mediated cellulase and xylanase production. The cellulose, hemicellulose and lignin contents of native straw were found to be 25.94%, 17.64% and 15.82%, respectively. However, in the acid/alkali treated straw, cellulose content substantially increased to 48.09%, whereas hemicellulose and lignin contents were reported to be particularly low (11.72%, 5.08%, respectively). The FTIR spectra of native and pre-treated paddy straw further supported the variation in their chemical constituents. A. terreus repertoires were cultivated on native and treated paddy straw under solid state fermentation (SSF) and liquid fermentation (LF) conditions. The LF cultures showed higher cellulase and xylanase activities (Filter Paper cellulase: 45.33 U/L, Carboxymethyl cellulase: 104.75 U/L, β-glucosidase 80.44 U/L, Avicelase: 22.72 U/L and Xylanase: 623.69 U/L) than the respective SSF cultures. Significantly high activities of exoglucanases and endoglucanases were obtained when native straw was used as the growth substrate. The scanning electron micrographs of native and treated straw exhibited disintegration after being subjected to biological treatments, confirming the hyphal adhered growth and production of hydrolysing secretomes by the fungus. Cultivation of A. terreus on native paddy straw in LF culture system resulted in better enzyme production, and holds promise for further optimization. [ABSTRACT FROM AUTHOR]

Burning corncob for energy requirements caused a huge waste of biomass resources and serious environment pollution. Herein, this study provided a high-value utilization strategy for corncob. Corncob was first pretreated by hydrothermal process. The collected hydrolysates were converted into furfural by a recyclable solid acid with a yield of 52.35%. The pretreated solid was disintegrated into fibers by disc grinding. When corncob fiber addition is below 15%, the ring crush index, tear index, and tensile strength index of the prepared handsheets increased by 1.43 N·m/g, 0.43 mN·m2/g, and 4.66 N·m/g, respectively, compared with that using pure softwood fibers. Besides, corncob fibers were hydrophilically modified with aminosulfonic acid. Water retention value of paper with the modified fiber addition increased by 48.35%. Therefore, this study provided a method of corncob utilization toward two purposes: furfural production and papermaking. [ABSTRACT FROM AUTHOR]

The surge in global biofuel demand is propelled by intensifying concerns over climate change and effective waste management. Government mandates on biofuel blending further boost this trend, underlining the significance of selecting renewable feedstocks, such as bioethanol and biodiesel, for biofuel production. The importance of selecting an efficient biomass pretreatment method cannot be overstated, given its status as the most energy-intensive and chemical-reliant step in the biofuel production chain. Thus, pretreatment becomes a crucial determinant in the feasibility and economic viability of biofuel technologies. Amid a wide array of pretreatment strategies, identifying a method that is both effective and sustainable is crucial for advancing biofuel commercialization. This review aims to rigorously evaluate both traditional and novel pretreatment techniques and their environmental footprints, leveraging life cycle assessment (LCA) studies from existing literature. By examining the sustainability of various pretreatment methods, this paper provides a holistic and clear view, serving as an essential resource for policymakers and industry stakeholders. It outlines the challenges faced in each phase of an LCA and proposes viable solutions. Additionally, the review furnishes valuable insights, recommendations, and directions for future research in achieving sustainable biofuel production. [ABSTRACT FROM AUTHOR]

Year after year, there are alarming data concerning the excessive release of greenhouse gases into the atmosphere, especially CO2 from the burning of fossil fuels. In this context, the development of renewable energy sources has evolved considerably, mainly due to the incentive use of biofuels, such as bioethanol. The second-generation bioethanol production from lignocellulosic biomasses has interesting potential to meet this energy demand. The Eucalyptus tree stands as a primary example of cultivated hardwoods, owing to its lignocellulosic structure and the biomass residues generated during its processing, where these attributes make it a significant candidate for the production of fuels. The industrial potential of these materials can be explored in the fractionation of their components to reduce their recalcitrance due to the triad formed by cellulose, hemicellulose, and lignin, for further processing and obtaining the products of interest. This paper comprehensively gathers the current technological progress employed for processing Eucalyptus wood biomasses for second-generation bioethanol production. Discussion regarding their chemical composition, the main forms of pretreatments that are being applied, and ways to minimize the generation of fermentative inhibitors during these processes is addressed. Finally, recent researches focused on Eucalyptus biomass-based bioethanol production and techno-economic considerations are discussed. The feasibility of the process is closely tied to the comprehensive utilization of products derived from this biomass. While production appears relatively effective at the laboratory scale, further research is required to develop a cost-effective process that fully harnesses the potential of the biomass. [ABSTRACT FROM AUTHOR]

This paper aims to study dark fermentation (DF) in an upflow anaerobic sludge blanket (UASB) reactor during 20 cycles operating at different hydraulic retention times (HRTs) of 3, 9, and 12 h using substrate wastewater from the food industry and granular inoculum sludge from a treatment plant as codigestion to explore the relationship between substrates, metabolites, and microorganisms to increase the biohydrogen (BioH2) yield. Operation conditions were constant pH 5.50 ± 0.50, T = 35 °C and a carbon-to-nitrogen (C/N) ratio of 30. It is noteworthy that DF with HRT = 9 h obtained the highest yields of organic matter degradation, and BioH2 in biogas (~60%) was attributed to the adjustment of pH and the codigestion buffer capacity. During DF with HRT = 9, the reactor was 11 times more productive with regards to HRT = 3 h, resulting in its performance with a better yield mean (6.22 mmol H2 g COD−1) and productivity (0.35 LH2 L−1 d) than other HRTs with lower records of 0.42 mmol H2 g COD−1 and 0.05 LH2 L−1 d, respectively. The high abundance of native populations (Lactobacillus and Lactococcus) and intrinsic inoculum (Citrobacter) led to the highest BioH2 production. Most of the production of acetic acid ~590 mg L−1 and butyric acid ~450 mg L−1 confirmed that BioH2 is mainly produced by acetic and butyric metabolic routes, and a direct relation with the percentage of retention of total suspended solids was also found, supporting the biodegradation capacity of the process. [ABSTRACT FROM AUTHOR]

Cellulolytic and hemicellulolytic enzymes are essential to make feasible the fully biochemical route for second-generation ethanol production. Solid-state fermentation figures as a low-cost and sustainable way of obtaining such enzymes by using agro-industrial by-products as substrates. In the current paper, thermal conditions and enzymatic activities from the cultivations of Myceliophthora thermophila, Trichoderma reesei, and Aspergillus niger were evaluated. Mixtures of sugarcane bagasse (SCB) as fibers or powder and wheat bran (WB) were used as substrates within a packed-bed bioreactor with variable packing density, as well as under two fluid flow configurations. Using SCB as fibers and WB 7:3 w/w (packing density 0.1 g/cm3) for M. thermophila, endoglucanase and xylanase activities overcame 850 and 3850 U/g, with temperature rise < 1 °C. Cultivations of M. thermophila and T. reesei in pure WB or with SCB as powder led to temperature rises of 7 to 16 °C, due to lower bed porosity. A. niger cultivations provided endoglucanase activities around 15 U/g under 8 ºC of maximum temperature rise, with no difference among percolating air and jacket water flowing in co- or counter current. The reported results address the importance of a strategic definition of the porous media composition and packing technique for a successful scale-up of the bioprocess, while giving operational flexibility in terms of fluid flow configuration. [ABSTRACT FROM AUTHOR]

Pleurotus pulmonarius is an economically important edible mushroom well known for the production of several lignocellulolytic enzymes, including polyphenol oxidase (PPO), EC 1.14.18.1. This enzyme can oxidize and hydrolyze phenolic compounds directly associated with the organoleptic and nutritional properties of foods. Thus, the aim of this paper is to produce and characterize the PPO of P. pulmonarius 21 (CCB21). The fungus was able to produce PPO using peach-palm waste and cocoa bean shell as substrates under solid-state fermentation (SSF) in 5 days of cultivation at 90% humidity (3066 ± 232 U/gds). PPO was partially purified with 60% ammonium sulfate and showed a purification rate of 2.1 times and a yield of 53.92%. The enzyme showed an optimum temperature above 45 °C, an optimum pH in the range of 5.5 to 6.5, and proved quite stable, maintaining 86–88% of its activity for up to 120 min under these conditions. PPO had reduced activity in the presence of β-mercaptoethanol, while EDTA, SDS, Al3+, Cu4+, Li4+, and Mg2+ ions increased their activity. The enzyme presented a Vmax of 4166.65 U/min and a Km of 4.16 mM for pyrocatechol. The results obtained suggest that, due to its thermostability and little influence in the presence of ions and reagents tested, the PPO of P. pulmonarius CCB21 can be an alternative for application in different biotechnological and industrial processes. [ABSTRACT FROM AUTHOR]

Biochar production from biomass sources is a highly complex, multistep process that depends on several factors, including feedstock composition (e.g., type of biomass, particle size) and operating conditions (e.g., reaction temperature, pressure, residence time). However, the optimal set of variables for producing the maximum amount of biochar with the required characteristics can be determined by using machine learning (ML). In light of this, the purpose of this paper is to examine ML applications in biochar processes for the production of sustainable fuels. First, recent developments in the field are summarized, and then, a detailed review of ML applications in biochar production is presented. Following that, a bibliometric analysis is done to illustrate the major trends and construct a comprehensive perspective for future studies. It is found that biochar yield is the most common target variable for ML applications in biochar production. It is then concluded that ML can help to detect hidden patterns and make accurate predictions for determining the combination of variables that results in the desired properties of biochar which can be later used for decision-making, resource allocation, and fuel production. [ABSTRACT FROM AUTHOR]

Straw management is extremely challenging, and irrational treatment can cause environmental pollution and affect the development of a circular economy in agriculture. The high-value utilization of agricultural straw as an important pathway to promote circular economy and achieve carbon neutrality goals has attracted much attention. Herein, the environmental and economic performance of the main straw-based fuel (straw-to-biochar, ethanol, and biogas) and material (straw-to-board and paper) utilization scenarios in China were compared from a life cycle perspective. This study is based on data from the eFootprint platform and the China Life Cycle Database. The results show that straw production for fuel has a better environmental performance than the production of materials option for water use, acidification potential, eutrophication potential, and respiratory inorganics. Utilizing straw to produce fuels or materials can reduce greenhouse gas emissions by 155–1296 kg CO2 eq. and decrease primary energy consumption by 8949–31270 MJ. Straw-to-board has the worst energy conservation and emission reduction performance but has the best economic performance with an LCC value of − 46.38 USD. The scenario with the shortest payback time is straw-to-ethanol, which take only 2 years. Sensitivity analysis reveals that the product has the most significant impact on the environmental and economic performance. The study analyzed the environmental impacts and economic benefits of these straw utilization pathways to provide solutions for sustainable straw management. [ABSTRACT FROM AUTHOR]

This work investigated the in situ catalytic pyrolysis of oil palm empty fruit bunch using CaO-impregnated zeolite (CaO/HZSM-5) catalyst. An optimum point was obtained via central composite rotatable design at reaction temperature of 567.10 °C, catalyst loading of 3.22 wt%, and CaO loading of 1.25 wt%, with an expected bio-oil yield of 35.31 wt%. Validation runs' experimental yield was 37.59 ± 1.74 wt%, indicating reliability of the condition. The impregnated catalyst was characterized, and CaO was observed to be successfully impregnated onto HZSM-5 with minor degradation on the catalyst structures. The bio-oil produced through catalytic pyrolysis had increased 16.102 wt% water content, and also lower acid content by 8.02%, and higher aromatic content by 18.86% as compared with non-catalytic pyrolysis, possibly contributed by the combined catalytic effect of CaO/HZSM-5 catalyst via deoxygenation and neutralization reactions. Kinetic study using Coats-Redfern method indicated the decrement of activation energy and frequency factor by 2.14% and 49.17%, respectively, at reaction order of three with addition of CaO/HZSM-5 catalyst. Similar reductions in activation energies in presence of CaO/HZSM-5 catalyst was observed in model-free methods, and the activation energies gradually increased with process conversion due to differences in valorization temperatures of hemicellulose (300 °C), cellulose (340 and 390 °C), and lignin (> 400 °C). [ABSTRACT FROM AUTHOR]