BioEnergy Research最新文献

This work presents a way to use ethanol and spent coffee grounds (SCG) as feedstocks for biodiesel production to solve ethanol overproduction in Thailand and biodiesel feedstock shortage problems together. Waste coffee oil (SCGO) was ethanolic extracted from SCG; then, ethanol-SCGO mixture was transesterified in supercritical condition without ethanol removal. The ethanolic extraction curves of SCG at a temperature range of 50–70 °C were constructed. Transesterification experiments were studied in a batch reactor and a continuous reactor at various temperatures (275–350 °C) and reaction time (5–40 min) under 15.0 MPa. The molar ratio of ethanol-oil mixture was set at 30:1. The highest ester content of 88.37 ± 3.00 wt% was found in biodiesel obtained at a temperature of 275 °C and a reaction time of 40 min in a batch reactor. Furthermore, excess temperature (< 300 °C) and reaction time (< 20 min) induced thermal degradation and promoted the loss of ethyl linoleate. For continuous reactor, the maximum ester content of 83.38 ± 5.86 wt% was observed at 325 °C and 29.4 min of residence time. Unlike in batch reactors, thermal degradation of ethyl linoleate was not observed in a continuous reactor. The results showed that ethanolic extraction and supercritical transesterification are alternative ways to produce biodiesel from SCG without removing extractant and using catalyst. From a prospective point of view, techno-economic analysis (TEA) and life-cycle assessment (LCA) of invented process should be conducted to ensure profitability and environmental benefits, respectively.

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Coppice plantations have gained a high interest for biofuel production and carbon uptake in short rotation cycles. There is a limited knowledge how such intensive coppice management affects soil fertility and nutrients supply to maintain carbon sink. We studied ecosystem carbon and nutrients balance and allocation during a 5-year period in hybrid aspen coppice under different thinning methods in hemiboreal Estonia. The benchmark value for the changes was defined before the coppice emerged after the clear-cut of the previously planted hybrid aspen plantation. The studied systematical thinning treatments were as follows: corridor thinning with removal of 67% of the trees (CT), cross-corridor thinning with removal of 89% of the trees (CCT), and unthinned (UT) coppice. The UT and CT treatments resulted in a positive carbon balance at the ecosystem level. In all treatments, a decrease of soil acidity, organic C, total N, K, Mg and Mn contents, and an increase of soil Cu and B contents were observed in the 0–20-cm deep layer. The concentrations of leaf N, P, and K were higher in UT than in the two thinning treatments, indicating that the aspens had not entirely recovered from the changed root to shoot ratio 2 years after thinning, whereas the leaf mass fraction of medium- and small-sized trees had already increased. Bioenergy harvest from the UT site in a 5-year rotation would cause 5–18% removal of NPK from the total ecosystem pool. Overall, hybrid aspen coppice showed positive ecosystem carbon balance after the first 5-year period; however, further monitoring of soil properties is needed as we found decrease of soil organic C and nutrients concentrations in short term.

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Substantial amounts of expired dairy products (EDP) are generated due to their high perishability. These wastes are rich in organic matter, and their landfill disposal negatively impacts the environment. An alternative to reducing and recovering this waste would be to use it as a substrate in anaerobic digestion (AD) to produce biogas. This study investigated methane (CH₄) production using different concentrations of EDP co-digested with synthetic domestic wastewater (SDW). Five anaerobic batch reactors (1000 mL) were assembled with different concentrations of EDP in SDW (500 mL working volume), namely (1) 0%, (2) 5.0%, (3) 7.5%, (4) 10.0%, and (5) 15.0% (v/v). COD removals were 81%, 84%, 80%, 89%, and 14% for assays 1 to 5, respectively. The cumulative CH₄ productions were (mL/L) 717, 3354, 5327, 6584, and 1156 for assays 1 to 5, respectively. Assay 5 (15% EDP) was inhibited by volatile fatty acid (VFA) accumulation. However, assays 2, 3, and 4 (with 5.0–10.0% EDP) showed high CH₄ yields (mLCH₄/gVS_add) of 319, 333, and 317, respectively, demonstrating the feasibility of anaerobic co-digestion of EDP with SDW. In assays 3 and 4, a similar archaeal community structure was observed, dominated by the genera Methanosaeta, Methanolinea, Methanoregula, and Methanobacterium. In assay 2, the archaeal community demonstrated lower dominance due to insufficient substrate adaptation. This study confirms the viability of using EDP in AD systems to generate CH₄, suggesting future sustainable applications for this residue.

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The increasing global population has led to a significant accumulation of food waste. It is important to focus on reducing food waste instead of disposal methods like landfilling and incineration, which have severe environmental impacts. Upcycling food waste has emerged as an effective strategy for repurposing discarded food into higher-value products. However, concerns about food safety and public acceptance of products directly produced from food waste persist. Consequently, there is growing interest in utilizing food waste rich in moisture and biodegradable organic compounds as a potential medium for cultivating microalgae. This review article examines the utilization of food waste as a culture medium for microalgae cultivation and the methods for treating food waste to enhance its nutrient content. Additionally, it discusses the influence of nutrients such as carbon, nitrogen, and phosphorus on microalgae growth and external factors such as pH and light intensity. The article also addresses the innovation of the food supply chain from environmental, social, and economic perspective, along with food safety and public acceptability concerns. Furthermore, it explores the legislative issues surrounding products derived from food waste and the end use of microalgae biomass produced from food waste. Overall, this review provides insight into the potential of microalgae cultivation using food waste, serving as a platform towards the realization of a circular bioeconomy.

Monolignols are efficiently synthesized from the corresponding cheap and readily available cinnamic acids through a borohydride reduction of the derived mixed carbonic anhydrides. Judicious choices of the reaction conditions allow for removal of the byproducts by aqueous workup and give the products cleanly in high yields.

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.