Biomass Components Research Articles

Thermal conversion studies of lignin pyrolysis and the catalytic effect of fe: A reactive molecular dynamics study

Lignin is one of the important components of biomass, and its pyrolysis process has been widely studied. The advantages of iron-based catalysts are their low cost, low environmental pollution, and the ability to extract and reuse from the system. However, research on the effect of metallic iron on lignin pyrolysis is limited. This study revealed the influence of iron on lignin pyrolysis process at the microscopic level through reactive molecular dynamics (ReaxFF MD) simulation, while considering the influence of different temperatures. It was found that increasing the temperature can increase the production of H2 and CO gases and improve the efficiency of lignin decomposition. In addition, the addition of catalyst iron can accelerate the decomposition of the benzene ring, making the lignin pyrolysis process deeper and more thorough, while increasing the production of H2 and CO. The activation energy of the system was calculated and it was found that the addition of catalyst iron can significantly reduce the activation energy of lignin pyrolysis, proving the excellent catalytic effect of the catalyst. The catalytic pyrolysis strategy provided in this study, using iron as a catalyst to catalyze the pyrolysis process of lignin, can effectively utilize biomass resources in industrial production.

Sustainability of biomass pyrolysis for bio-aromatics and bio-phenols production: Life cycle assessment of stepwise catalytic approach

The high-valued utilization of biomass resources remains challenging due to their complex biochemical compositions and limited product selectivity. Herein, we propose a novel biomass stepwise catalytic pyrolysis process to efficiently produce aromatic hydrocarbons and phenols by leveraging the distinct thermal stability of biomass components and their compatibility with ZSM-5 and biochar-based catalysts. A life cycle assessment (LCA) is conducted to evaluate the energy consumption and environmental impact of this innovative process compared to conventional methods. Our findings reveal that this approach significantly reduces the energy consumption by 51.76–90.02 % across different application scenarios of by-product biochar. Additionally, using biochar as a soil amendment contributes to carbon negativity, achieving a net greenhouse gas (GHG) emission reduction of up to 6 t CO2 eq for producing 8.325 t aromatics and 1 t phenol. The first-stage catalytic pyrolysis for producing aromatic hydrocarbons is identified as the major contributor to environmental impact, mainly due to ZSM-5 catalyst usage and loss, while the second stage for phenol production has a comparatively minor impact. Finally, sensitivity analysis of the key parameters highlights areas for process optimization, including reducing catalyst dosage, minimizing energy consumption, and improving phenol yield, which are crucial for enhancing the environmental and economic viability of the entire route. This study provides a detailed LCA and offers insights for future improvements in biomass conversion technology.

Carbon quantum dots from carbohydrate-rich residue of birch obtained following lignin-first strategy

Carbon quantum dots (CQDs) were successfully synthesized from carbohydrate-rich residue of birch obtained following the lignin-first strategy. The optical and physicochemical properties of the CQDs were studied, along with their potential for photocatalytic pollutant degradation. By combining solvothermal and chemical oxidation methods, the product yield of CQDs from carbohydrate-rich residue reached 8.1 wt%. Doping nitrogen enhances the graphitization of CQDs and introduces abundant amino groups to the surface, thereby boosted the quantum yield significantly from 8.9 % to 18.7 %-19.3 %. Nitrogen-doped CQDs exhibited efficient photocatalytic degradation of methylene blue, reaching 37 % within 60 min, with a kinetic degradation rate of 0.00725 min−1. This study demonstrates that carbohydrate-rich residue obtained from lignin-first strategy are ideal precursors for synthesizing CQD with high mass yield and quantum yield by combining solvothermal treatment and chemical oxidation methods, offering a novel approach for the utilization of whole biomass components following the lignin-first strategy.

Development of an Effective Au : Pd Bimetallic Heterogeneous Catalyst for Oxidative Lignin Depolymerization to Low Molecular Weight Aromatics

AbstractLignin, a phenolic‐rich biomass component, holds promise for producing value‐added products. However, its complex structure and recalcitrance present challenges for its effective utilization. To overcome this, a AuPd/Li−Al layered double hydroxide (LDH) catalyst was developed to facilitate lignin depolymerization. Various AuPd bimetallic nanoparticle compositions were supported on a basic Li−Al LDH support via a sol‐immobilization method and characterized using N2‐physisorption, X‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The catalysts were then evaluated in the oxidation of several benzylic alcohols using O2 as the oxidant, from which Au7Pd3/Li−Al LDH and Au1Pd1/Li−Al LDH were identified as possessing promising catalytic activity. Further investigations focused on the aerobic oxidation of β‐O‐4 linked lignin model dimers under atmospheric pressure. The tested catalysts demonstrated sequential oxidation of the model compounds, leading to cleavage of the β‐O‐4 linkage. Finally, the catalysts were applied to the oxidative deconstruction of γ‐valerolactone (GVL) extracted maple lignin at 120 °C. Au1Pd1/Li−Al LDH emerged as the most effective catalyst, yielding a range of aromatic monomers with a total monomer yield of 27 %. These results highlight the potential of the Au1Pd1/Li−Al LDH catalyst system as an eco‐friendly approach for lignin depolymerization under mild conditions.

One pot green process for facile fractionation of sorghum biomass to lignin, cellulose and hemicellulose nanoparticles using deep eutectic solvent

Complete valorization of lignocellulosic biomass is crucial for bio-based biorefineries to fulfil the circular bioeconomy concept. However, the existence of lignin carbohydrate complexes (LCC) in biomass hinders the simultaneous fractionation of biomass components, such as lignin, hemicellulose and cellulose, for subsequent biorefining processes. This study explores for the first time a novel approach tailored for the deconstruction of sorghum biomass components through efficient breakdown of LCC. Selective targeting of the major LCC linkages binding xylan and lignin was performed using an ultrasound-assisted deep eutectic solvent under mild treatment conditions. This process yielded a maximum cellulose content of 98.3 %, hemicellulose content of 95.2 %, and lignin content of 94.6 %, with the highest purities of 99.43 %, 96.71 %, and 98.12 %, respectively. FTIR, 2D-HSQC NMR and XRD analyses confirmed that most of the structural properties of lignin, hemicellulose, cellulose are retained. The lignocellulosic components were successfully valorised to cellulose, hemicellulose, and lignin nanoparticles with mean sizes of 64.5 ± 6 nm, 72.8 ± 4 nm and 57.2 ± 8 nm respectively, with good thermal stability. The proposed green process enables the complete utilization of agro-residue feedstock for the preparation of biomass-derived nanoparticles, thereby accelerating the economic and industrial prospects of bio-based biorefineries.

Structural changes and grading mechanism of lignin during solid alkali-active oxygen extraction and grading

Cooking with active oxygen and solid alkali (CAOSA) is an efficient pretreatment method for biomass. For better grading of the lignin yellow liquor, the different lignin fractions and the recovered solid alkali were obtained using a simultaneous acid-alkali graded separation method. The results indicated that the recovery rate of solid alkali was 67.25 %, and the grading of lignin components was characterized by smaller dispersion coefficients, and more stable properties and structure. Lignin fractions with low dispersion coefficients possess more key structures, including the Phenol hydroxyl group (ArOH), Methoxy (OMe), and β-aryl ether (β-O-4), and have better thermal properties. The low molecular weight L4 has the highest ArOH content (2.1 mmol/g), which provides better antioxidant properties. The CAOSA process destroyed the S-unit and prevented lignin from condensation. Furthermore, the CAOSA process protected carbohydrates, which could effectively prevent them from dehydrating and re-polymerizing into pseudo-lignin. This allowed the pulp to remain natural, which was beneficial for subsequent transformation and utilization. Overall, the efficient separation of biomass components and lignin grading method proposed by combining the CAOSA process with the acid-alkali grading separation method has a strong application prospect and provides a theoretical basis for the high-value utilization of biomass and lignin.

Unravelling the complexity of hemicellulose pyrolysis: Quantitative and detailed product speciation for xylan and glucomannan in TGA and fixed bed reactor

For the first time, the complete characterization of the pyrolysis of key biomass components – xylan (representative of pentose-based hardwood hemicellulose) and glucomannan (representative of hexose-based softwood hemicellulose) – is herein obtained by applying a novel methodology based on TGA (thermogravimetric analysis), previously developed for cellulose. Data on devolatilization rates, onset temperatures and detailed quantification of the mass yield of ∼ 50 products in the gas, liquid, solid phase were achieved simultaneously, with closure of mass balance, thus providing unique kinetic information. Pyrolysis tests were also carried out in a fixed bed reactor to explore larger scales and validate the TGA-based approach. At both scales, combinations of different analytical techniques (online MS, offline GC-FID/MS, Karl Fischer titration) and sampling protocols (cold condenser, sorbent traps, vapour syringes, gas bags) were tuned to achieve closure of mass balances and rigorous product speciation.While the pyrolysis of cellulose – chosen as reference system − maximized the bio-oil production (mostly levoglucosan), the pyrolysis of xylan resulted into an even distribution among solid, liquid and gas phases, with condensable oxygenates spanning homogeneously in the C1-C9 range. Interestingly, glucomannan showed an intermediate behaviour between cellulose and xylan, mirroring its intermediate chemical structure. Raman and oxidation analyses on the collected char samples showed that the solid residuals from hemicelluloses were less ordered and richer in ashes than those from cellulose.The predictions of recent lumped kinetic models were used to benchmark the new datasets against the prior art on hemicellulose pyrolysis; the richness and comprehensiveness of the new information clearly emerge and pave the pathway to the de-bottlenecking of kinetic modelling.

Supercritical CO2 as effective wheat straw pretreatment for subsequent mild fractionation strategies

The efficient utilization of lignocellulosic biomass in biorefineries is pivotal for the transition to a carbon–neutral society, emphasizing the need for environmentally friendly fractionation techniques. While the extensive use of chemicals in biorefinery operations can yield favorable quantities of specific biomass components, adopting less chemically intense conditions is crucial for holistic methodologies that preserve the inherent potential of all biomass constituents. This study comprehensively investigates the use of supercritical carbon dioxide (sc-CO2) as a green pretreatment to improve subsequent mild fractionation on wheat straw. Sc-CO2 at 300 bars, 100 °C and 70% moisture was found to have minimal impact on the chemical composition and the lignin structure, while there were significant morphological changes as heightened surface area and reduced density. Apart from increasing enzymatic saccharification efficiency, the treatment notably enhanced subsequent mild delignification through alkaline and flow-through organosolv extractions. The combination of the pretreatments enhances the lignin solubilization yields from 49 to 79% for alkaline and 74 to 91% for organosolv extractions, while retaining a high β-O-4 conservation of 49 and 59 linkages per 100 aromatic units, respectively. Additionally, the combined use of sc-CO2 with mild dilute acid pretreatment improved xylose solubilization from 59 to 76 % and enzymatic saccharification from 53 to 90%, albeit with increased lignin condensation. In summary, this study demonstrates the potential of sc-CO2 pretreatment as a versatile tool for biomass valorization within the evolving bioeconomy, by combining enhanced extraction yields with minimal lignin structural impact. Our work thereby highlights the promise of the use of sc-CO2 to contribute to the overall economic potential of improved biorefinery processes.

Range-wide salamander densities reveal a key component of terrestrial vertebrate biomass in eastern North American forests.

Characterizing the population density of species is a central interest in ecology. Eastern North America is the global hotspot for biodiversity of plethodontid salamanders, an inconspicuous component of terrestrial vertebrate communities, and among the most widespread is the eastern red-backed salamander, Plethodon cinereus. Previous work suggests population densities are high with significant geographic variation, but comparisons among locations are challenged by lack of standardization of methods and failure to accommodate imperfect detection. We present results from a large-scale research network that accounts for detection uncertainty using systematic survey protocols and robust statistical models. We analysed mark-recapture data from 18 study areas across much of the species range. Estimated salamander densities ranged from 1950 to 34 300 salamanders ha-1, with a median of 9965 salamanders ha-1. We compared these results to previous estimates for P. cinereus and other abundant terrestrial vertebrates. We demonstrate that overall the biomass of P. cinereus, a secondary consumer, is of similar or greater magnitude to widespread primary consumers such as white-tailed deer (Odocoileus virginianus) and Peromyscus mice, and two to three orders of magnitude greater than common secondary consumer species. Our results add empirical evidence that P. cinereus, and amphibians in general, are an outsized component of terrestrial vertebrate communities in temperate ecosystems.

Distribution of xylan linked glucuronic acid labelled by molecularly imprinted polymers on pulp fiber surface

Efficiently utilization of plant resources is heavily restricted by the resistance of lignocellulose in plant cells, which is related to the interlinkages of lignocellulose components. Hemicellulose in plant cell wall is bound to cellulose by hydrogen bond and linked with lignin in lignin-carbohydrate complex (LCC). In the xylan chain of hemicellulose, glucuronic acid (GA) is a typical side-group, which provides clues for us to label and locate hemicellulose. The way to label GA on the surface of pulp fibers obtained from pulping process is benefit to explore the deconstruction of lignocellulose. Herein, a new visualization method, fluorescence modified molecularly imprinted polymers (MIP) were applied to recognize and locate GA on the pulp fiber surface. The method combining fluorescence imaging and integrated 3D fiber structure verified the feasibility of the MIP for specific GA recognition. The results showed that xylan (represented by GA) was closely attached to lignin, distributed along the inner wall of pulp fiber cells, and gradually taken off from the inside edge of fiber cells with the deconstruction of lignocellulose. This research provided a basis to develop visualization bioimaging technology to identify biomass components.

Microwave-assisted pyrolysis of industrial biomass waste: Insights into kinetic, characteristics and intrinsic mechanisms

Microwave-assisted pyrolysis is the preferred technology for enhancing the production of fuels and valuable chemicals. Therefore, pyrolysis experiments of furfural residue (FR) were performed using microwave equipment without microwave-absorbing additives. Further, to explore the interactions and intrinsic mechanisms of biomass components, thermogravimetric (TG), kinetic calculation, Py-GC/MS and TG-MS were also employed. Results showed that the temperatures and catalysts both affect the yields and compositions of products. Moreover, kinetic calculations showed a high-level consistency between FR pyrolysis and P3 mechanism. The product analysis also helps in the resolution of pyrolysis mechanism. For example, crystal substances in biochar were mainly SiO2, K2SO4, KAlSi3O8, and K2SO4 enhanced the reaction degree of biomass. While for bio-oil, the yield reached maximum (∼25 wt%) at ∼550 °C. The pH of bio-oil was acidic (2–4.3), and the main product in bio-oil was phenols, which was found the highest (84.63 %) at 700 °C. Interestingly, the interaction of cellulose and lignin promoted light hydrocarbon production. This research unveils innovative perspectives on the intrinsic mechanisms underlying microwave-assisted pyrolysis of biomass, which provides guidance for optimization of the microwave-assisted pyrolysis technology.

Experimental analysis of the effects of feedstock composition on the plastic and biomass Co-gasification process

Co-gasification is a feasible approach to manage fast-growing plastic and biomass waste issues. The current work examines air gasification of plastic waste blending with biomass. The influence of plastic-type and biomass characteristics on product distribution under the same operating condition was studied. Ethylene-vinyl acetate, high-density polyethylene, and polypropylene were the investigated plastics while the biomass materials considered were pine sawdust (PS), used ground coffee (UGC), and wheat straw (WS) are compared. Additionally, co-gasification and thermogravimetric analyses (TGA) of plastic and individual biomass components, namely, cellulose, hemicellulose, and lignin, were conducted to identify the nature of the synergy arising from plastic and biomass integration. Similarities in the chemical structure and composition of the investigated plastics resulted in the type of plastic marginally influencing product distribution. The gas composition included 4.6 vol% CH4, 37.5 % CO2, 5.3 % CnHm, 42 % CO, and 10.8 % H2, with yields of 5.9 wt% char, 39.5 wt% gas, and 54.8 wt% tar. Conversely, the type of biomass had a substantial effect on both gas composition and product yields. WS and UGC, characterized by higher hemicellulose and lignin content, generated more hydrogen with 14.4 and 13.3 vol%, respectively, and exhibited lower tar content (45.7 and 47.8 wt%) compared to PS, which has a higher cellulose content and yielded 54.8 wt% tar. During EVA/cellulose co-gasification, the predominant gases produced are CO and CO2, with H2 concentration of 7.2 vol%. In contrast, co-gasification of EVA/xylan and EVA/lignin yields 13.5 and 19.9 vol% hydrogen, respectively. Interactions and synergism between the plastic and biomass were found to be more intensified when the biomass contained greater proportions of cellulose and lignin. Co-gasification and TGA analyses indicated that plastic/cellulose and plastic/lignin interactions in the gas and solid phases (volatile-volatile and volatile-char interactions) and plastic/xylan interactions in the gas phase (volatile-volatile interactions) were significant. Modeling the predictability of the output data revealed that if interactions between the plastic and biomass components are accounted for, the co-gasification results are predictable with a credible accuracy for all biomass types. The predictability model offers a practical approach for selecting an appropriate co-gasification feedstock combination to give a targeted process performance.

Callus Induction and Enhancing the Production of Biomass and Pharmaceutical Components of Thymus decussatus as an Endangered Medicinal Plants in Egypt

Callus Induction and Enhancing the Production of Biomass and Pharmaceutical Components of Thymus decussatus as an Endangered Medicinal Plants in Egypt

Oxidative and selective C–C cleavage of glycerol to glycolaldehyde with atom-like Cu on Cu-TiO2: Photocatalytic water reduction with concurrent glycerol oxidation in sunlight

Concurrent consumption of electrons and holes for the conversion of a biomass component to value added products represents a highly efficient and sustainable approach towards utilizing renewable energy, but difficult to achieve. The integration of hydrogen production with glycerol oxidation presents a novel and sustainable approach towards achieving a circular economy. In the current study, integration of atom-like Cu-clusters onto TiO2 substrate has been achieved using a facile photo-deposition technique (TC-PDO). Also, novel synthetic approaches have been employed to augment the surface coverage of Cu on TiO2 with atom-like clusters of Cu, either by borohydride treatment on TiO2 followed by Cu-deposition (TC-200) or oxygen-vacancy creation by UV illumination followed by Cu-deposition (TC-PDO). Increased dispersion and enhanced electronic integration of Cu with TiO2 lead to a corresponding increase in the efficiency of photocatalytic hydrogen evolution (13.8 mmol/h.g for TC-PDO at pH 9). Several atom-like Cu integrated with each TiO2 particle acts as photocatalytic reactor, and the same enhances electron-hole separation as well as activity. Sustainable aspect was also studied for TC-PDO up to 25 h at pH 9. Concurrently, glycerol oxidation displays the highest selectivity to C2 product (glycolaldehyde with 70 %) with a C–C cleavage. The investigation of this process holds significant potential for the extensive and simultaneous exploitation of electrons and holes in order to achieve water splitting and glycerol oxidation towards selective value-added products formation.

Phytoplankton biomass responses to a marine heat wave align with altered nitracline depth

AbstractThe 2014–2015 warm anomaly (aka “the Blob”), the largest of periodic and intensifying marine heat wave (MHW) perturbations in the northeast Pacific, may provide some insight about the future warmer ocean. Here, we use mixed‐layer carbon estimates for total phytoplankton, major size classes and functional groups from 45 CalCOFI cruises to: (1) compare 2014–2015 MHW impacts in the southern California Current System to baseline estimates from 2004 to 2013 and (2) to test a space‐for‐time exchange hypothesis that links biomass structure to variability of nitracline depth (NCD). Seasonal and inshore‐offshore analyses from nine stations revealed almost uniform 2°C MHW warming extending 700 km seaward, fourfold to sixfold declines in nitrate concentration and 18‐m deeper NCDs. Phytoplankton C decreased 16–21% compared to 45–65% for Chl a, with the threefold difference due to altered C : Chl a. Among size classes, percent composition of nanoplankton decreased and picophytoplankton increased, driven by higher Prochlorococcus biomass, while Synechococcus and picoeukaryotes generally declined. Diatom and dinoflagellate C decreased in both onshore and offshore waters. Seasonally, the MHW delayed the normal winter refresh of surface nitrate, resulting in depressed stocks of total phytoplankton and nanoplankton, Synechococcus and picoeukaryotes during winter. Consistent with the space‐for‐time hypothesis, biomass variations for baseline and MHW cruises followed similar (not significantly different) slope relationships to NCD. All biomass components, except Prochlorococcus, were negatively related to NCD, and community biomass structure realigned according to regression slopes differences with NCD variability. Empirically derived biomass‐NCD relationships could be useful for calibrating models that explore future food‐web impacts in this coastal upwelling system.

Agronomic performance of Ciherang near-isogenic lines for nitrogen use efficiency trait in irrigated lowland paddy field

Abstract Nitrogen (N) is an essential nutrient that affects plant growth and productivity. The consumption of N fertilizer is continuously increasing with the rapid demand for agricultural production. However, the rise in N fertilizer utilization causes higher production costs and leads to a negative impact on the environment. Improvement in nitrogen use efficiency (NUE) of rice plants is therefore important for sustainable rice production to reduce N fertilizer consumption while maintaining high grain yield. To improve the NUE of Indonesian elite cultivars, near-isogenic lines (NILs) with Ciherang genetic background have been developed by introducing genes related to N use efficiency, qRL6.1, and actpk1 through backcross breeding. Preliminary yield trials were conducted to evaluate the agronomic performance of CiherangNILqRL6.1 and CiherangNILactpk1 rice lines under optimum N fertilizer conditions in irrigated lowland fields for two seasons, wet season 2021/2022 and dry season 2022. Observations were performed on flowering time, biomass, yield, and yield component of NILs and Ciherang. The result from this preliminary observation indicated that under optimum N fertilizer, the agronomic performance of the NILs was comparable to Ciherang as the genetic background. Some NILs showed higher grain yield compared to Ciherang and were selected for further experiments to evaluate their performance under different N fertilizer conditions.

Influence of different stalks on the metallization degree of FeCl3-derived magnetic biochar through pyrolysis behavior and compositional differences

To investigate the effect of stalk type on the metallization degrees in FeCl3-derived magnetic biochar (MBC), MBC was synthesized via an impregnation-pyrolysis method using six different stalks. The Fe0 content in MBC significantly influenced its magnetic properties and ostensibly governed its catalytic capabilities. Analysis of the interaction between stalks and FeCl3 revealed that the variation in metallization degrees, resulting from FeCl2 decomposition (6.1%) and stalk-mediated reduction (20.7%), was directly responsible for the observed differences in MBC metallization. The presence of oxygen-containing functional groups and fixed carbon appeared to promote metallization in MBC induced by reduction. A series of statistical analyses indicated that the cellulose, lignin, and hemicellulose content of the stalks were key factors contributing to differences in MBC metallization degrees. Further exploration revealed that hemicellulose and cellulose were more effective than lignin in enhancing metallization through FeCl2 decomposition and reduction. Constructing stalk models demonstrated that the variance in the content of these three biomass components across the six stalk types could lead to differences in the metallization degree attributable to reduction and FeCl2 decomposition, thereby affecting the overall metallization degree of MBC. A prediction model for MBC metallization degree was developed based on these findings. Moreover, the elevated Si content in some stalks facilitated the formation of Fe2(SiO4), which subsequently impeded the reduction process. This study provides a theoretical foundation for the informed selection of stalk feedstocks in the production of FeCl3-derived MBC.

Co-pyrolysis of cellulose and lignin: Effects of pyrolysis temperature, residence time, and lignin percentage on the properties of biochar using response surface methodology

Cellulose, hemicellulose, and lignin constitute the basic components of biomass. Knowledge of the interactions between cellulose and lignin during pyrolysis is crucial for unraveling the pyrolysis characteristics of biomass. In this study, for the co-pyrolysis of cellulose and lignin to produce biochar, three influencing factors were selected: pyrolysis temperature (400–800 °C), residence time (5–30 min), and lignin percentage (0–100 %). Pyrolysis experiments were conducted in a vertical tube furnace and the impact of these three factors on the characteristics of biochar was comprehensively explored employing response surface methodology. The results revealed obvious differences between actual values and theoretical values. Specifically, the results showed that the interaction between cellulose and lignin increased the biochar yield, oxygen content, volatile content, and ash content by 6.14 %, 22.85 %, 30.95 %, and 46.75 %, respectively. In contrast, the carbon content, fixed carbon content, and HHV of biochar were relatively reduced by 9.38 %, 11.80 %, and 3.3 %, respectively. Furthermore, Raman spectra of biochar showed that the actual value of graphitization degree of biochar was higher than the theoretical value. This was further corroborated by XPS analysis, wherein owing to the interactions between cellulose and lignin, the actual C-C bond content decreased in contrast to the theoretical value. However, the contents of C-O, CO, COOH functional groups, and aromatic rings increased. Finally, the summary of the co-pyrolysis rules of cellulose and lignin provided a reference for optimal pyrolysis conditions and understanding the mechanism of co-pyrolysis.

Hydrothermal Carbonization Technology for Wastewater Treatment under the “Dual Carbon” Goals: Current Status, Trends, and Challenges

Hydrothermal carbonization (HTC) technology transforms organic biomass components, such as cellulose and lignin, into valuable carbon materials, gases and inorganic salts through hydrolysis, degradation and polymerization, with significant advantages over traditional methods by reducing energy consumption, lowering pollutant emissions and enhancing carbonization efficiency. In the context of global climate change, HTC plays a critical role in water environment management by addressing industrial, agricultural, and domestic wastewater challenges. The application of HTC extends to wastewater treatment, where hydrochar effectively adsorbs heavy metals, organic compounds, and anions, thereby improving water quality. However, challenges remain, such as optimizing the process for diverse raw materials, managing economic costs, and addressing environmental and social impacts. Future research and policy support are essential for advancing HTC technology. By enhancing reaction mechanisms, developing catalysts, and promoting international cooperation, HTC can significantly contribute towards achieving carbon neutrality goals and fostering sustainable development.

Unraveling interspecies cross-feeding during anaerobic lignin degradation for bioenergy applications

Lignin, a major component of plant biomass, remains underutilized for renewable biofuels due to its complex and heterogeneous structure. Although investigations into depolymerizing lignin using fungi are well-established, studies of microbial pathways that enable anaerobic lignin breakdown linked with methanogenesis are limited. Through an enrichment cultivation approach with inoculation of freshwater sediment, we enriched a microbial community capable of producing methane during anaerobic lignin degradation. We reconstructed the near-complete population genomes of key lignin degraders and methanogens using metagenome-assembled genomes finally selected in this study (MAGs; 92 bacterial and 4 archaeal MAGs affiliated into 45 and 2 taxonomic groups, respectively). This study provides genetic evidence of microbial interdependence in conversion of lignin to methane in a syntrophic community. Metagenomic analysis revealed metabolic linkages, with lignin-hydrolyzing and/or fermentative bacteria such as the genera Alkalibaculum and Propionispora transforming lignin breakdown products into compounds such as acetate to feed methanogens (two archaeal MAGs classified into the genus Methanosarcina or UBA6 of the family Methanomassiliicoccaceae). Understanding the synergistic relationships between microbes that convert lignin could inform strategies for producing renewable bioenergy and treating aromatic-contaminated environments through anaerobic biodegradation processes. Overall, this study offers fundamental insights into complex community-level anaerobic lignin metabolism, highlighting hitherto unknown players, interactions, and pathways in this biotechnologically valuable process.