BioEnergy Research最新文献

Whey, a cheese production byproduct, can be anaerobically digested to reduce pollution and generate energy. Yet, stability is challenging due to organic content sensitivity and influent fluctuations. The present work attempts to implement the mechanistic model and machine learning (ML) models (support vector regression (SVR) and artificial neural networks (ANNs)) together to predict the concentration dataset of substrate 1 (S₁) (i.e., carbohydrates and proteins), substrate 2 (S₂) (i.e., glucids and amino acids), VFA, and methane (CH₄) as a function of input independent variables, namely time and organic loading rate (OLR). The R² values for S₁, S₂, VFA, and CH₄ obtained through the mechanistic model remained as 0.953, 0.918, 0.84, and 0.976, respectively; for ANN models, 0.982, 0.928, 0.958, and 0.99; and for SVR models, 0.984, 0.939, 0.938, and 0.999, respectively. ML models have been discovered to be among the most precise and versatile compared to the mechanistic model. Moreover, other performance metrics, such as RMSE (0.022–2.177), MRE (0.007–0.100), and AARE (0.008–0.104) for ANN and RMSE (0.083–1.961), MRE (0.021–0.091), and AARE (0.037–0.089) for SVR, are obtained, indicating good prediction performances for both ML models. SVR and ANN models excel, aligning concentration curves to the optimum line when input parameters are adjusted, unlike the subpar traditional-based mechanistic model. Therefore, ML methods offer a tool to predict anaerobic digestion more effectively, enhancing design and operations.

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This article presents an energy-efficient biochar kiln that produces biochar from agricultural crop residues. The kiln is designed to be easy to operate and has minimal requirements for special operations. It works by heating biomass in a combustion chamber using recirculated pyrogas. The study optimized the process parameters and economics of producing biochar from wheat straw using Response Surface Methodology (RSM) based on Central Composite Design (CCD). The sustainable pyrolyzer had a thermal efficiency of 43.69%, with steady-state operation at 517.68 ± 98.18 °C. It produced an average of 54.57 ± 1.86 kg of biochar per batch, using 36.96 ± 3.66 kg of subabul (Leucaena leucocephala) as fuel and 179.61 ± 2.87 kg of wheat straw as feedstock. Subabul is chosen as a fuel due to its rapid growth, high calorific value, low moisture content, efficient combustion, and minimal smoke emission. The thermogravimetric index (TGI) and calorific value of WSB were 7.14 and 25.91 ± 0.74 MJ/kg, respectively. The benefit–cost ratio and payback period were 2.27 ± 0.16 and 4.92 ± 0.44 months, respectively.

The co-pyrolysis behavior of pine sawdust (PS) biochar doped with copper slag (CS) and the adsorption performance of the prepared CS catalyzed composite adsorbent is studied. Thermogravimetric, SEM, and BET are used to analyze the co-pyrolysis characteristics and the adsorption performance of PS and its mixed samples with different ratios of PS and CS. The co-pyrolysis of CS and PS effectively improves the pyrolysis characteristics. Compared with PS pyrolysis alone, with little change in activation energy, the reaction order changed from 1.5 to 0.5. When the mixing ratio PS:CS = 3:1, the pyrolysis release characteristics were the highest; the most favorable for the pyrolysis reaction. The H₃PO₄, KOH, and ZnCl₂ used to modify PS biochar improved its adsorption capacity. The results show that the modified PS biochar has a larger specific surface area and provides more adsorption sites, effectively improving the adsorption effect. The adsorption capacity of the PS biochar is inversely proportional to the concentration of the Cr(VI) solution. Under the conditions of modified PS at 1:1 based on H₃PO₄, KOH, and ZnCl₂, the concentration of the Cr(VI) solution is 20 mg, and the adsorption effect is best in an acidic environment with pH = 1. The high value-added utilization of metallurgical solid waste and agricultural waste was realized, namely the governance concept of “treating danger with waste.”

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.

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.