BioEnergy Research最新文献

The fermentation of whole slurry favors the increase in ethanol titers and minimizes water consumption. However, inhibitors accumulate in the liquid fraction pretreatment, reducing fermentation performance. In order to find a way out, the present study proposed an integration between cloud point extraction (CPE) and ethanol production using fiber of green coconut (GCF) as substrate. Triton X-114 was used to detoxify the liquid fraction from acid pretreatment, and optimal operating conditions were obtained by mathematical modeling. The effects of the residual surfactant from the dilute phase of CPE were analyzed in cellulase adsorption tests, enzymatic hydrolysis, and fermentation of acid-pretreated GCF. CPE promoted high removal of furans (86.23–100%) and phenolic compounds (22.79–75.15%), while the sugars migrated to the dilute phase. A neural network model coupled with a genetic algorithm obtained an optimal condition of 2.38% Triton X-114, temperature of 42 °C, pH of 4.3, and 0.55% sodium chloride. The incubation with the CPE dilute phase increased the residual activity from 25.1 to 50.1% and increased the cellulosic conversion from 32.28 to 41.15%. CPE-saccharification and simultaneous fermentation integration boosted the ethanol production to 12.40 g/L, while the untreated whole slurry reached only 6.29 g/L. Because of these results, the CPE emerges as a promising alternative to favor the full use of sugars from lignocellulosic biomass.

The single-pass, split-stream harvest of corn grain and stover has been extensively studied. Challenges for these systems include the logistics and economics of handling separate grain and stover streams. Single-pass, single-stream processes have been explored using a self-propelled forage harvester to collect whole-plant corn as a biomass feedstock. However, due to the processing done by the self-propelled forage harvester, a significant portion of the grain fraction is damaged during harvest limiting its marketability. To evaluate an alternative system, a combine harvester was modified with a rear blower to collect corn stover, facilitating the collection of the grain and stover fractions into the same wagon, creating an aggregate, whole-plant corn material. Utilizing this system, a plot study was conducted to compare it to a self-propelled forage harvester. Parameters studied for system performance were yield, grain damage, and geometric mean particle size. While the combine system reduced grain damage (p < 0.001) by 18 percentage points compared to the self-propelled forage harvester and had a similar whole plant particle size (p = 0.11), it collected 1.86 Mg DM ha⁻¹ less biomass (p < 0.001). The combine harvester with a stover collection system provides a method to collect whole-plant corn as a biomass feedstock that maintains a large portion of the grain integrity but decreases dry matter yield.

A study of the energy potential from agro-industrial waste of Mangifera indica L. in the city of Zamora, Michoacán is presented, considering its use through solid biofuels. This research is composed of three stages: (a) the qualitative and quantitative diagnosis of the waste disposal of M. indica, spatiotemporally (b) the physicochemical characterization of the waste collected from 14 processing companies using characterization techniques, as well as proximal analysis of the moisture content, ash, volatiles, fixed carbon, and calorific value, and (c) estimation of the energy potential to spatially and temporally define the final energy disposition and possible use of the analyzed waste. The results show the ash content of mango residues below 3.5%, while the volatile material was 82.9%, the fixed carbon content was below 17%, and the polymeric compounds showed 27.24% cellulose, 10.46% for hemicellulose, and for lignin 5.78%. The presence of carbon was also identified in the order of 44.61%, hydrogen in 6.53%, oxygen in 48.11%, nitrogen of 0.74%, and the sulfur recorded was below the range of 0.01%. The calorific value was estimated from 17.5 to 19.28 MJ/kg; the available energy potential on the order of 0.5 TJ/day for 4 months. This proposal not only shows a case study of the bioenergy potential available, but it can also encourage addressing future research related to the use and valuation of agro-industrial waste, which, like in the Zamora region, there are many more in Mexico, and they are so diverse and productive that the energy potential is relevant.

Hydrothermal liquefaction (HTL) of lignocellulosic biomass has gained attention as a promising technology for the production of biofuels and other value-added products. HTL process optimization is complex and involves various parameters such as reaction time, temperature, and pressure. In recent years, machine learning (ML) approaches have been adopted as a tool to optimize and predict the HTL process performance. The purposes of this study were to investigate the ML-based prediction of bio-crude yield (BCY) and their higher heating values (HHVs) from HTL of lignocellulosic biomass and to elucidate the relationship of features affecting the output of interest. Pre-processing and normalization were applied to a dataset of 215 data points with 17 input features. Feature selection using the Shapley value method identified key predictors. ML models including multilayer perceptron, kernel ridge regression, random forest, and extreme gradient boosting (XGB) were trained and evaluated. XGB algorithm shows superior performance in predicting the yields and their calorific values to within 5–8% of experimental values. Temperature was the most influential feature for both BCY and HHV prediction accounting for about 30%, followed by other feedstock and operational characteristics. In addition, a user interface was presented for ease of use in the ML modeling.

Rice straw hydrolysate produced in rice straw pretreatment, comprising a lot of fermentable sugars, is generally released into the environment. This not only causes environment pollution but also wastes fermentable sugars from rice straw. To alleviate environment impact, maximize ethanol production from rice straw, and reduce the cost of ethanol production, rice straw hydrolysate and NaOH-pretreated rice straw were converted to ethanol using ethanol-type fermentation and simultaneous saccharification and fermentation (SSF) by sludge. Meanwhile, microbial community in sludge was analyzed to find the relationship between ethanol production and microbial community succession during ethanol-type fermentation and SSF. Under the optimal condition of the COD, pH and oxidation–reduction potential (ORP) value of rice straw hydrolysate with 6280.56 mg/L, 6.7, and − 42 mV, ethanol-type fermentation with the sludge of 15 g obtained the highest ethanol concentration (8.34 g/L) and the highest COD removal rate (54.83%). For SSF, the maximum ethanol concentration (3.75 g/L) produced by pretreated rice straw and sludge from ethanol-type fermentation with the sludge of 15 g was higher than that (2.61 g/L) generated by pretreated rice straw and sludge from ethanol-type fermentation with the sludge of 22.5 g. This indicated that sludge from ethanol-type fermentation with the sludge of 15 g more efficiently converted rice straw to ethanol than sludge from ethanol-type fermentation with the sludge of 22.5 g. Microbial community analysis suggested that ethanol production had a negative correlation with the relative abundance changes of Bacteroidetes, when the relative abundance of Firmicutes constantly rose in ethanol-type fermentation and SSF. This study provides a scientific basis for maximizing ethanol production from rice straw by microbial regulation in sludge, which could further reduce the cost of ethanol production.

Enzymatic catalysts, such as lipases, have been extensively studied due to their promise as an alternative to chemical catalysts. They offer advantages like biodegradability (green biotechnology) and the potential for enzyme recycling (turnover), leading to reduced operational costs. The primary objective of this study was to produce lipase from the fungus Penicillium polonicum through solid-state fermentation, utilizing agro-industrial waste as substrate. The aim was to apply the obtained lipase as a biological catalyst in the synthesis of ethyl oleate ester. In the lipase production process, the filamentous fungus P. polonicum, along with sunflower seed cake (SSC) and rice husk (RH), served as substrate and support, respectively, for solid-state fermentation (SSF). Experiments involved varying proportions of both substrate and support (0%, 25%, 50%, 75%, and 100% (RH) and 100% (SSC)). Subsequently, the impact of glycerol as an inducer (1%, 3%, and 5%, with a 25/75% SSC/RH ratio) at SSF was investigated. The obtained results revealed a catalytic activity of 29.3 U g⁻¹ under optimal conditions: 55% moisture, 25/75% SSC/RH, and at 27 °C during 96 h of fermentation. The lipase produced was employed as an enzymatic catalyst in studies involving the synthesis of ethyl oleate ester in n-heptane, utilizing experimental design 2³. Variables such as temperature, enzymatic activity, and molar ratio (alcohol/acid) were modified. The best experimental conditions for the enzymatic synthesis of ethyl oleate ester were determined to be an alcohol/acid molar ratio of 6:1, a temperature of 37 °C, and an enzymatic activity of 60 U. This resulted in 100% conversion into ester within 5 h of reaction time. The outcomes demonstrated that lipase effectively catalyzed the synthesis of ethyl oleate, a biodiesel ester, with a high yield.

β-Glucosidases for industrial applications are mainly obtained from filamentous fungi. Kretzschmaria zonata is a phytopathogen fungus that produces an arsenal of enzymes with biotechnological potential and this work aimed to produce, purify, and characterize a β-glucosidase from the fungus K. zonata for its application in supplementation of a commercial cocktail for sugarcane bagasse saccharification. The elevated specific activity of β-glucosidase was induced by corn cob, reaching 1.085 U/mg of protein. At the end of all purification steps, a purification factor of 6.52 was reached, with an increase of specific activity from 1.22 U/mg, in the crude extract, to 7.97 U/mg. Concerning pH stability, at pH 4, the pH of maximal β-glucosidase activity, the enzyme was completely stable, with 100% activity after 1 h of incubation, while it kept over 50% activity in the pH range from 2.2 to 6. The optimum temperature was 60 °C and the half-life times were estimated as 307.8 and 10 min, for temperatures of 60 and 70 °C, respectively. The β-glucosidase showed a reduction in relative activity in the presence of 10 mM of manganese sulfate, zinc sulfate, manganese chloride, SDS, and glucose, maintaining 55, 56, 62, 70, and 73% of the relative activity, respectively. The commercial cocktail Multifect® CL supplemented with the K. zonata β-glucosidase enabled the release of 13.89 g/L of glucose and 5.34 g/L of xylose, an increase of 19.8 and 35.5% of glucose and xylose release, respectively, after sugarcane bagasse hydrolysis.

Xylooligosaccharides (XOS) are potential prebiotic ingredients for food industries, mainly obtained after xylan hydrolysis by endoxylanases. Enzyme immobilization offers opportunities for recovery and reuse, while also enhancing its physical and chemical characteristics, such as stability and catalytic efficiency. This work aimed to immobilize the SM2 xylanase derived from the xynA gene from Orpinomyces sp. PC-2 and to evaluate its potential for XOS production. For this, SM2 xylanase was immobilized using the cross-linking methodology. The free and immobilized enzymes were characterized regarding the effect of pH, temperature, and thermostability. The cross-linked enzyme aggregate was evaluated for reuse and storage conditions and used for xylooligosaccharide production. Both free and immobilized SM2 xylanase showed maximal activity at 60 °C. The immobilized enzyme was more active at acidic and neutral conditions, and the free enzyme showed greater activity at basic conditions. The half-life of the free and immobilized xylanase was 30 and 216 h, respectively. In reuse tests, enzymatic activity increased with each cycle, and there was no statistical difference in the activity of SM2 xylanase aggregate stored at 4 and 25 °C. After saccharification, xylobiose (0.895 g/L), xylotriose (0.489 g/L), and xylohexose (0.809 g/L) were detected. As a result, immobilization enhanced thermostability, shifted the pH of maximum activity to 5, facilitated reuse, and eliminated the need for refrigerated packaging. Finally, the xylooligosaccharides produced by the SM2 xylanase are known for their prebiotic role, providing potential application of the immobilized enzyme in the food industry.

The rapid proliferation of giant Salvinia (GS; Salvinia molesta) in various hydrostatic environments, such as ponds and paddy fields, poses a threat to water quality due to light obstruction. Thus, this study aimed to transform GS biomass into hydrochar or solid biofuel via hydrothermal carbonization (HTC). Several parameters were examined, including residence time, reaction temperature, and liquid-to-solid mass ratio (L/S). The Box-Behnken Design (BBD) was also employed to set the experimental conditions at three levels and factors. The examinations of reaction temperature (200–220 °C), residence time (2–6 h), and L/S ratio (12–20) were conducted. The physical and chemical characteristics of hydrochar were further analyzed to encompass higher heating value (HHV), proximate analysis, ultimate analysis, functional group, and morphology. The percent energy recovery (ER, %) was remarked for the experimental design response. The kinetic analysis and a comprehensive combustibility index, calculated from TGA/DTG curves, were employed to elucidate the combustion behavior of hydrochar. The optimal condition for hydrochar production, resulting in maximal ER, was identified at 220 °C, 6 h, with an L/S ratio of 16. The corresponding fixed carbon (FC), HHV, and mass yield were approximately 17.2%, 23.5 MJ/kg, and 51.4%, respectively. The H/C and O/C mole ratios in the sub-bituminous coal region. This study affirms the feasibility of converting GS biomass into a renewable fuel resembling low-rank coal.

Marine photosynthetic microbial fuel cells (mpMFCs) can utilize marine photosynthetic microorganisms to drive electrical energy-generating electrochemical reactions. Due to improved ionic mobility and superior electrical conductivity of seawater, it is a suitable electrolyte for operating bio-electrochemical devices at operating elevated salinities. This study examined the use of seawater as a conducting medium in two-chambered MFCs to enhance power production in conjunction with a marine photosynthetic biocathode as an alternative to the abiotic chemical cathode. Using a modified BG11 seawater medium as catholyte, marine cyanobacteria were grown and maintained in the MFC cathode compartment. After a significant quantity of biomass had formed, it was harvested for use as the substrate for anode microorganisms. Isolated marine cyanobacteria from photosynthetic biocathode were identified using 16 s rRNA and Sanger DNA sequencing. In electrochemical characterization, mMFC, maximum power density (P_max) was 147.84 mWm⁻² and maximum current density (J_max) reached 1311.82 mAm⁻². In mpMFC, P_max was 104.48 mWm⁻² and J_max was 1107.27 mAm⁻². P_max was 53.14 mWm⁻² and J_max was 501.81 mAm⁻² in comparable freshwater MFC employing platinum catalyst, which proves that mMFC and mpMFC worked better. Dapis pleousa and Synechococcus moorigangaii were identified as dominant marine cyanobacteria. It was demonstrated that mpMFC, operated using seawater and employing a cyanobacteria biocathode, is suitable for circularized renewable energy production. The outcomes of this study imply that mpMFCs are good candidates for circular renewable energy production.