Bioresource Technology最新文献

Methanation of carbon dioxide (CO₂) is a key process for improving carbon utilization technology. In this study, we investigated a novel approach to biomethanation from hydrogen (H₂) and CO₂ using an anaerobic membrane bioreactor under mesophilic conditions. System performance was evaluated by varying carbon loading rates, with a focus on decarbonization efficiency, carbon mass flow, and microbial dynamics. The results demonstrated stable operation and strong resilience, achieving a decarbonization efficiency higher than 84 % and a methane (CH₄) flow-out rate of 1.1 L/L/d at a carbon loading rate of 1.0 g-C/L/d. Carbon mass balance showed that CH₄ accounted for 43.8-82.4 % of influent carbon. Microbial analysis indicated a clear shift from a diverse consortium to a Methanobacterium-dominant community, with its relative abundance increasing from 4.2 % to 47.8 %. Gene expression analysis revealed upregulation of key methanogenesis genes (fwd, mtr, and mcrA). Our findings provide valuable insight into the development of scalable ex-situ biomethanation systems.

High-strength organic wastes such as fat, oil, and grease (FOG) are promising co-substrates for anaerobic digestion (AD) due to their high energy content. However, the accumulation of long-chain fatty acids (LCFAs) often leads to microbial inhibition and process instability. This study evaluated the effectiveness of oyster shell biochar (OSB) as a dual-function additive that integrates calcium supplementation and electrical conductivity to improve AD performance. OSB demonstrated enhanced methane production performance, attributed to its ability to accelerate early-stage microbial activity and maintain system stability. Microbial analysis showed the selective enrichment of Methanothrix and Smithella, supporting the potential involvement of direct interspecies electron transfer (DIET). These findings suggest that OSB can simultaneously promote chemical buffering and microbial stimulation. As a low-cost, waste-derived material, OSB offers a practical and sustainable strategy to improve the efficiency of lipid-rich waste digestion and contributes to the advancement of functional biochar applications in AD systems.

Sustainable management of sewage sludge (SewS) requires efficient strategies for energy recovery and nutrient reutilization. An anaerobic membrane bioreactor (AnMBR) and a continuous stirred tank reactor (CSTR) were operated to evaluate the advantages of membrane-integrated systems in SewS management. The AnMBR achieved a methane yield of 313.5 mL-CH₄/g-VS_add, which was 11.3% higher than that of the CSTR, attributed to the extended sludge retention time facilitated by membrane-induced biomass retention. The AnMBR also enhanced the potential for resource recovery by accumulating agricultural nutrients, with 817 g/t-SewS of NH₄⁺-N and 395 g/t-SewS of Total Phosphorus retained in the permeate and filtrate-representing 40.4% and 10.6% increases compared to CSTR. The AnMBR-digested sludge saved 65.1% flocculant for dewatering. With a higher exergy efficiency (11.8% vs. 10.6% for the CSTR), the AnMBR exhibited feasibility for resource recovery, suggesting its applicability for integrated SewS management.

A novel side-stream-enhanced biological phosphorus removal system was successfully operated for 203 days, with controlled influent carbon-to-phosphorus ratio (25.8), side-stream influent (20 %), and oxidation-reduction potential (-150 to - 300 mV). This system facilitated synergistic collaboration of Candidatus Accumulibacter, Dechloromonas, and side-stream fermentative microorganisms, without relying on Tetrasphaera. During two-stage operation, COD and PO₄^3--P removal efficiencies increased from 73.7 % and 75.3 % to 83.2 % and 91.8 %, respectively. The system exhibited high biological activity, with peak phosphorus release of 49.3 mg·L^-1, a 66 % increase from Phase I. Microbial analysis revealed the enrichment of Candidatus Accumulibacter (12.9 %) and Dechloromonas (6.2 %) in the mainstream reactor. Key genes and enzymes related to phosphorus removal were also enriched. Overall, the experiment achieved stable system operation, with Candidatus Accumulibacter and Dechloromonas effectively collaborating with fermentative microbes. Future research will focus on optimizing parameters and evaluating their potential for large-scale wastewater treatment applications to enhance stability and reduce costs.

Camellia oleifera shell (COS), a lignin- and hemicellulose-rich cultivation byproduct, offers significant potential for resource extraction. In this study, we developed an integrated biorefinery approach using mild metal chloride-catalyzed hydrothermal pretreatment to vaporize COS waste. Under optimized conditions (0.03 M AlCl₃, 170 °C, 60 min), hemicellulose-rich COS was selectively depolymerized into xylo-oligosaccharides (XOS) with a yield of 49.8 %. This efficient Lewis acid-catalyzed method produced high XOS yields and cellulose- and lignin-enriched solid residues. Compared to untreated samples, these residues, with reduced hemicellulose content, yielded hard carbon with increased interlayer spacing and closed pore structures, exhibiting superior sodium storage ability. This approach contrasts with traditional enzymatic hydrolysis and fermentation pathways. The hard carbon anode was incorporated into sodium-ion batteries, demonstrating practical feasibility with an initial reversible capacity (IRC) of 348 mAh g^-1, an initial coulombic efficiency (ICE) of 70.5 %, and capacity retention of 91.7 % after 100 cycles. This dual-product approach maximizes COS utilization and synergizes renewable chemical production with advanced energy storage, highlighting the unique advantages of our approach to XOS synthesis and material optimization, showcasing a clear advantage over existing single-product pathways.

On-demand electricity generation from biogas can be achieved through variable feeding regimes using easily degradable substrates, such as sugar beet. However, such substrates pose a high risk of foam formation in anaerobic digesters. This study aimed to identify foam-causing compounds in anaerobic digestion of sugar beet silage and to evaluate effective countermeasures. Pectin was identified as primary contributor to foaming during anaerobic digestion of sugar beet silage, while saponins had no effect. Pectinase pre-treatment of sugar beet silage reduced foaming by 30%. Furthermore, the antifoaming effect of seven vegetable oils was compared. Sunflower oil showed the highest foam suppression efficacy, while soybean oil had almost no effect. The acid number of vegetable oils, reflecting the content of free fatty acids, correlated most strongly with their antifoaming performance. These findings show practical strategies for effective foam control during anaerobic digestion of sugar beet silage, enabling flexible feeding for on-demand biogas production.

For the design of biomass gasification it is beneficial to have models which can predict the composition of gas products for a wide range of different biomass feedstocks. Complex machine learning models (e.g. neural networks and tree-based methods) are now being used for this purpose which are difficult to reproduce with large numbers of parameters involved. In this study the potential for higher order polynomials is investigated for the modelling of bubbling fluidised bed gasification. To reduce the number of parameters and to avoid over-fitting Least Absolute Shrinkage and Selection Operator (LASSO) regularisation is used. This is a novel application of high order polynomial regression with regularisation which allows the prediction of hydrogen composition with coefficient of performance of 0.9228 and only 85 fitted parameters. The next best existing methods give coefficients of performance of 0.8823 and 0.868 but require 261 parameters and more than 1000 parameters respectively. So this polynomial approach is shown to give accurate model prediction with simpler model equations.

Hydrothermal humification (HTH) of biomass is a promising approach to address the depletion of soil organic matter. However, the HTH products derived from lignocellulose are limited by low nutrient availability and conversion efficiency. In this study, four nitrogen-containing additives were used to produce nitrogen-rich artificial humic acids (AHA) from crop waste. The addition of urea, ammonium chloride, ammonium sulfate, and ammonium dihydrogen phosphate at 180 °C for 1 h significantly improved both the yield and quality of AHA. Optimal conditions were achieved using ammonium sulfate at a carbon-to-nitrogen ratio of 5, resulting in an impressive AHA yield of 40.75 ± 3.99 wt% and a nitrogen content of 3.54 %, closely resembling naturally formed humic acids. This represented a 38.27 % increase in yield and a 30.44 % increase in nitrogen content compared to the control. Moreover, 5NS-AHA exhibited reduced aromaticity, increased oxygen-containing functional groups, and enhanced functionality through the regulation of aliphatic and aromatic carbon structures. The concentration of furfural in the hydrothermal aqueous phase reduced from 43.48 % to 29.85 %. Ammonium sulfate optimized the HTH pathway through synergistic mechanisms involving acid-catalyzed oxidation, nitrogenated condensation, and aromatic condensation. This work provides a visible pathway for producing nitrogen slow-release AHA fertilizers from agricultural waste.