Lignocellulosic Research Articles

Pretreatment of lignocellulosic biomass for bioethanol production

This review surveys recent progress in pretreatment methods for enhancing bioethanol production from lignocellulosic biomass. Various pretreatment techniques, including physical, chemical, and biological approaches, are evaluated for their efficacy in breaking down biomass structure and improving enzymatic digestibility. Key parameters influencing pretreatment effectiveness and integration with downstream processes are discussed. The review highlights promising strategies and identifies areas for further research to optimize bioethanol production from lignocellulosic feedstocks.

Removal of Methylene blue dye from contaminated wastewater using lignocellulosic biomasses: A comparative study

In this study, lupine seed (Lu-SP) and pumpkin seed shells (PSSP) biomasses were used to create alternative and effective adsorbents. Methylene blue (MB) dye was removed from wastewater using the as-prepared adsorbents at variables solution pH 2.0 –11.0, contact period (0–180 min), and adsorbent mass (0.2–2.0 g/L). The solution pH had a synergistic effect on the improved removal of MB and the optimal adsorption removal for both adsorbents occurred at pH 8.0 and 120 min. The adsorption isotherm modelling results showed a good fit with the Langmuir model, with a maximum monolayer adsorption capacity of 48.98 and 77.48 mg/g for PSSP and Lu-SP, respectively. Similarly, the pseudo-first-order (PFO) model is regarded as the best-fit kinetic model for both adsorbents and suggests the predominance of physisorption via interfacial diffusion. Mechanistic investigation of the present system suggests that both intraparticle diffusion and surface sorption mechanisms control the adsorption rate. Notably, the Lu-SP with a lower surface area (54.013 m2/g) outperformed the PSSP (235.992 m2/g) in terms of adsorption capacity under varying pH. Therefore, in addition to electrostatic interaction, adsorption into the micropores via volume filling is considered one of the adsorption mechanisms. This study, therefore, revealed that the PSSP and Lu-SP may be very helpful for removing cationic MB dye from contaminated wastewater.

Role of Particle Geometry on the Structural Integrity of Sand and Rock Ilmenite Used as Oxygen Carrier in Combustion of Woody Biomass

Role of Particle Geometry on the Structural Integrity of Sand and Rock Ilmenite Used as Oxygen Carrier in Combustion of Woody Biomass

Synergism of jet milling and deep eutectic solvent pretreatment on grapevine lignin fractionation and enhancing enzymatic hydrolysis

Herein, we investigated the synergistic effects of jet milling (JM) and deep eutectic solvent (DES) pretreatment on the fractionation of grapevine lignin and the consequent enhancement of enzymatic hydrolysis. Grapevine, a substantial byproduct of the wine industry, was subjected to JM pretreatment to produce finely powdered particles (median diameter D50 = 98.90), which were then further treated with acidic ChCl-LA and alkaline K2CO3-EG DESs. The results revealed that the combined JM + ChCl-LA pretreatment significantly increased the cellulose preservation under optimal conditions (110 °C, 4 h, and 20 % water content), achieving removal rates of 74.18 % xylan and 66.05 % lignin, respectively. The pretreatment temperature and inhibitor production were reduced, resulting in a remarkable threefold increase in glucose yield compared to untreated samples. Moreover, the structural analysis of the pretreated lignin indicated an enrichment of phenolic units, leading to enhanced antioxidant and antibacterial activities, particularly in the JM pretreated samples. These findings underscore the promising potential of the synergistic JM and DES pretreatment in facilitating the efficient utilization of grapevine lignocellulosic biomass for sustainable biorefinery technologies.

Biochar from co-pyrolysis of biological sludge and woody waste followed by chemical and thermal activation: end-of-waste procedure for sludge management and biochar sorption efficiency for anionic and cationic dyes.

Nine biochars were produced by co-pyrolysis of sawdust and biological sludge following the "design of experiment" approach. Two kinds of sludge (both deriving from the treatment of mixed industrial-municipal wastewater) and two types of woody waste were selected as categorical predicting variables, while contact time, pyrolysis temperature, and sludge percentage were used as quantitative variables. Biochars were analysed for their product characteristics and environmental compatibility based on the European Standards (EN 12915-1:2009) for materials intended for water treatment (i.e. ash content, water leachable polycyclic aromatic hydrocarbons (PAHs) and elements), as well as for specific surface area (SSA), using them as response variables of a multivariate partial least square multiple regression, whose results provided interesting insights on the relationships between pyrolysis conditions and biochar characteristics. Biochars produced with sludge and/or providing the highest SSA values (258-370 m2g-1) were selected to undergo a sustainable chemical treatment using a by-product of the gasification of woody biomass, complying in all cases with European Standards and achieving therefore the end-of-waste status for sewage sludge. The biochar deriving from the highest percentage of sludge (30% by weight) and with the highest SSA (390 m2g-1) was thermally activated achieving SSA of 460 m2g-1 and then tested for the sorption of direct yellow 50 and methylene blue in ultrapure water and real wastewater, compared to a commercial activated carbon (AC). The biochar showed Langmuir sorption maxima (Qm) 2-9 times lower than AC, thus highlighting promising sorption performances. Qm for methylene blue in wastewater (28mg‧g-1) was confirmed by column breakthrough experiments.

Unlocking the Full Potential of Green Catalysis: a Novel Thermosensitive Catalytic System for Ultrasonic-microwave Liquefaction of Woody Biomass

Unlocking the Full Potential of Green Catalysis: a Novel Thermosensitive Catalytic System for Ultrasonic-microwave Liquefaction of Woody Biomass

Role of Woody Biomass Ash Material in Immobilization of Cadmium, Lead and Zinc in Soil

Nowadays, we have observed the dynamic development of bio-heating plants that use wood biomass for heating or energy purposes. The result of this process is a reduction in carbon dioxide emissions as well as in the production of biomass ash (BA). Despite the waste nature of BA, it should be carefully analyzed and assessed for various applications, including environmental ones. Due to the features attributed to BA, including its alkaline reaction, the high capacity of its sorption complex, relatively low salinity, and significant content of macro- and microelements, a hypothesis was put forward in this work undertaken about the positive role of BA as an immobilizing factor for Cd-, Pb-, and Zn-contaminated soils. This research was based on a pot experiment in which four series were considered: (1) BA; (2) BA + Cd; (3) BA + Pb; and (4) BA + Zn. BA was used at doses of 30, 60, and 90 mg pot−1, and metals at doses of 2 mg Cd, 100 mg Pb, and 300 mg Zn kg−1 of soil. The test plant was corn grown for green mass. The study took into account the influence of BA on the content of the total forms of heavy metals (Metot) and their available forms (Meav). In the soil without the addition of metals, a significant increase in the content of Cdtot and Cdav, and a decrease in the content of Zntot were observed due to the application of BA. The addition of metals against the background of the BA used resulted in a significant increase in Cdtot, Pbtot, and Zntot, as well as an increase in the available forms of Pbav but a decrease in Znav. However, there was no significant increase in the Cdav content. The obtained results may indicate the potentially immobilizing role of BA only in the case of zinc. They may constitute the basis for further, more detailed research aimed at determining the role of BA in the immobilization of various metals in soil.

Integrated biorefinery approach for utilization of wood waste into levulinic acid and 2-Phenylethanol production under mild treatment conditions

In a bid to explore the on-site biorefinery approach for conversion of forestry residues, lignocellulosic biomass into value-added products was studied. The bark white pine wood was subjected to the microwave technique of fast and slow hydrolysis under varying acid and biomass concentrations to produce levulinic acid (LA). The HCl (2% v/v) and plant biomass (1% w/v) were identified as the optimum conditions for fast wood hydrolysis (270 ºC for 12 sec), which led to maximum LA yield of 446.68 g/kgPB. The proposed sustainable approach is mild, quick, and utilized a very low concentration of the HCl for the production of LA. The hydrolysate was used as a medium for Kluyveromyces marxianus growth to produce 2-phenylethanol (2-PE). K. marxianus used 74–95% of furfural from hydrolysate as a co-substrate to grow. The proposed model of the integrated biorefinery is an affordable on-site approach of using forest waste into localized solutions to produce LA and 2-PE.

Lignin Degradation by Klebsiella aerogenes TL3 under Anaerobic Conditions

Lignin, the largest non-carbohydrate component of lignocellulosic biomass, is also a recalcitrant component of the plant cell wall. While the aerobic degradation mechanism of lignin has been well-documented, the anaerobic degradation mechanism is still largely elusive. In this work, a versatile facultative anaerobic lignin-degrading bacterium, Klebsiella aerogenes TL3, was isolated from a termite gut, and was found to metabolize a variety of carbon sources and produce a single kind or multiple kinds of acids. The percent degradation of alkali lignin reached 14.8% under anaerobic conditions, and could reach 17.4% in the presence of glucose within 72 h. Based on the results of infrared spectroscopy and 2D nuclear magnetic resonance analysis, it can be inferred that the anaerobic degradation of lignin may undergo the cleavage of the C-O bond (β-O-4), as well as the C-C bond (β-5 and β-β), and involve the oxidation of the side chain, demethylation, and the destruction of the aromatic ring skeleton. Although the anaerobic degradation of lignin by TL3 was slightly weaker than that under aerobic conditions, it could be further enhanced by adding glucose as an electron donor. These results may shed new light on the mechanisms of anaerobic lignin degradation.

Hydrothermal enzyme pretreatment on structure and properties of apple branches

Hydrothermal enzyme pretreatment on structure and properties of apple branches

Soil mycobiomes in native European aspen forests and hybrid aspen plantations have a similar fungal richness but different compositions, mainly driven by edaphic and floristic factors

BackgroundThe cultivation of short-rotation tree species on non-forest land is increasing due to the growing demand for woody biomass for the future bioeconomy and to mitigate climate change impacts. However, forest plantations are often seen as a trade-off between climate benefits and low biodiversity. The diversity and composition of soil fungal biota in plantations of hybrid aspen, one of the most planted tree species for short-rotation forestry in Northern Europe, are poorly studied.MethodsThe goal of this study was to obtain baseline knowledge about the soil fungal biota and the edaphic, floristic and management factors that drive fungal richness and communities in 18-year-old hybrid aspen plantations on former agricultural soils and compare the fungal biota with those of European aspen stands on native forest land in a 130-year chronosequence. Sites were categorized as hybrid aspen (17–18-year-old plantations) and native aspen stands of three age classes (8–29, 30–55, and 65-131-year-old stands). High-throughput sequencing was applied to soil samples to investigate fungal diversity and assemblages.ResultsNative aspen forests showed a higher ectomycorrhizal (EcM) fungal OTU richness than plantations, regardless of forest age. Short-distance type EcM genera dominated in both plantations and forests. The richness of saprotrophic fungi was similar between native forest and plantation sites and was highest in the middle-aged class (30–55-year-old stands) in the native aspen stands. The fungal communities of native forests and plantations were significantly different. Community composition varied more, and the natural forest sites were more diverse than the relatively homogeneous plantations. Soil pH was the best explanatory variable to describe soil fungal communities in hybrid aspen stands. Soil fungal community composition did not show any clear patterns between the age classes of native aspen stands.ConclusionWe conclude that edaphic factors are more important in describing fungal communities in both native aspen forest sites and hybrid aspen plantation sites than forest thinning, age, or former land use for plantations. Although first-generation hybrid aspen plantations and native forests are similar in overall fungal diversity, their taxonomic and functional composition is strikingly different. Therefore, hybrid aspen plantations can be used to reduce felling pressure on native forests; however, our knowledge is still insufficient to conclude that plantations could replace native aspen forests from the soil biodiversity perspective.

Extraction of homogeneous lignin oligomers by ozonation of Miscanthus giganteus and vine shoots in a pilot scale reactor

Lignin, a complex phenolic polymer crucial for plant structure, is mostly used as fuel but it can be harnessed for environmentally friendly applications. This article explores ozonation as a green method for lignin extraction from lignocellulosic biomass, aiming to uncover the benefits of the extracted lignin. A pilot-scale ozonation reactor was employed to extract lignin from Miscanthus giganteus (a grass variety) and vine shoots (a woody biomass). The study examined the lignin extraction and modification of the fractions and identified the generation of phenolic and organic acids. About 48 % of lignin was successfully extracted from both biomass types. Phenolic monomers were produced, vine shoots yielding fewer monomers than Miscanthus giganteus. Ozonation generated homogeneous lignin oligomers, although their molecular weight decreased during ozonation, with vine shoot oligomers exhibiting greater resistance to ozone. Extracted fractions were stable at 200 °C, despite the low molecular weight, outlining the potential of these phenolic fractions.

Estimating the energy return on investment of forestry biomass: Impacts of feedstock, production techniques and post‐processing

AbstractThe Energy Return On Investment (EROI) is a recognised indicator for assessing the relevance of an energy project in terms of net energy delivered to society. For woody biomass divergences remain on the right methodology to assess the EROI leading to large variations in the published estimates. This article presents an in‐depth discussion about the EROI of woody biomass in three different forms: woodchips, pellets and liquid fuels. The conceptualisation of EROI is further developed to reach a consistent definition for biomass post‐processed fuels. It considers, on top of the external energy investments, the grey energy associated with the energy used to enrich the fuel. With the proposed methodology, all woodchips have an EROI of the same order of magnitude, between 20 and 37, depending on forestry types, operations and machineries. For secondary residues, the first estimate is 170 if, as co‐products, no energy investment is allocated to the forestry operations and transport. On the basis of a mass allocation for forestry operations and transport, the EROI for secondary residues becomes of the same order of magnitude as that for wood chips. Woodchips can be further post‐processed into pellets or liquid fuels. Pellets have an EROI of 4–7 if the heat is externally supplied and 8–23 if internally supplied (self‐consumption of part of the raw material). Liquid fuels derived from primary wood and residues through gasification and Fischer‐Tropsch synthesis have an EROI between 4 and 16. Fuel enhancement with hydrogen (Power & Biomass to Liquids) impacts negatively the EROI due to the low EROI of hydrogen produced from renewable electricity. However, these fuels offer other advantages such as improved carbon efficiency. A correct estimate of EROI for forestry biomass, as proposed in this work, is a necessary dimension in assessing the suitability of a project.

Enhanced upgrading of lignocellulosic substrates by coculture of Saccharomyces cerevisiae and Acinetobacter baylyi ADP1

BackgroundLignocellulosic biomass as feedstock has a huge potential for biochemical production. Still, efficient utilization of hydrolysates derived from lignocellulose is challenged by their complex and heterogeneous composition and the presence of inhibitory compounds, such as furan aldehydes. Using microbial consortia where two specialized microbes complement each other could serve as a potential approach to improve the efficiency of lignocellulosic biomass upgrading.ResultsThis study describes the simultaneous inhibitor detoxification and production of lactic acid and wax esters from a synthetic lignocellulosic hydrolysate by a defined coculture of engineered Saccharomyces cerevisiae and Acinetobacter baylyi ADP1. A. baylyi ADP1 showed efficient bioconversion of furan aldehydes present in the hydrolysate, namely furfural and 5-hydroxymethylfurfural, and did not compete for substrates with S. cerevisiae, highlighting its potential as a coculture partner. Furthermore, the remaining carbon sources and byproducts of S. cerevisiae were directed to wax ester production by A. baylyi ADP1. The lactic acid productivity of S. cerevisiae was improved approximately 1.5-fold (to 0.41 ± 0.08 g/L/h) in the coculture with A. baylyi ADP1, compared to a monoculture of S. cerevisiae.ConclusionThe coculture of yeast and bacterium was shown to improve the consumption of lignocellulosic substrates and the productivity of lactic acid from a synthetic lignocellulosic hydrolysate. The high detoxification capacity and the ability to produce high-value products by A. baylyi ADP1 demonstrates the strain to be a potential candidate for coculture to increase production efficiency and economics of S. cerevisiae fermentations.

Incorporating pruning into the carbon footprint of tree production based on terrestrial laser scanning

Pruning is a major source of carbon emissions from urban trees. The high cost of evaluating pruning quantities by destructive measurements has limited the research on pruning. By combining terrestrial laser scanning and quantitative structure models, pruning quantities can be assessed non-destructively. This study focuses on the impact of pruning during tree production, as it is intense and has been rarely evaluated. Using Sophora japonica from a nursery in Beijing as an example, point cloud data were collected from 181 uneven-aged Sophora japonica for the simulation of pruning at a single tree level. All pruning stages were incorporated into the assessment of the carbon footprint of Sophora japonica production for 15-year-old trees. The results show that previous studies have underestimated the tree carbon footprints of pruning, leading to a severe underestimation of the carbon footprint of tree production. Crown reduction removes the most above-ground woody biomass during tree production, over half, while the decomposition of pruning waste is the most significant source of carbon emissions. The removal ratio from pruning of individual trees is consistent within the same pruning pattern. The tree volume can serve as a good predictor for estimating pruning quantities, but crown diameter sometimes needs to be considered. Implementing pruning interventions, harvesting in advance, and choosing appropriate methods for pruning waste disposal can reduce carbon emissions from pruning.

PSIII-21 Impact of high zinc oxide supplementation or lignocellulose supplement on chronic markers of intestinal inflammation and growth of weaned piglets

Abstract The objective of this project was to study the effects of high zinc oxide (ZO) supplementation and fiber supplement from lignocellulose (LIGCEL) on chronic markers of intestinal inflammation and growth of weaned piglets. At weaning (21 d), 150 piglets (body weight = 6.39 ± 0.276 kg) were transferred from a farrowing farm to a nursery farm where they were divided into 30 pens of 5 piglets per pen according to their weanling weight. Each pen was assigned to one of the following three treatments: Control (CON, 150 mg/kg of zinc), ZO (2,500 mg/kg of zinc), and LIGCEL (CON+3% lignocellulose). The ZO and LIGCEL supplements were added to a phase 1 diet. The experimental diets (phase 1) were distributed for 14 d. Subsequently, all piglets received the same diets from phases 2 and 3 for two periods of 14 d. During the experiment, piglets were weighed upon arrival and after phases 1, 2, and 3. The feed was distributed every day and the total quantities calculated for each of the feeding phases. The average daily gain (ADG), average daily feed intake (ADFI) and feed conversion (FC) were subsequently calculated (Table 1). On d 6 and 13, the blood of two piglets per pen was collected to determine the content of D-lactate and diamine oxidase (DAO). Fecal samples from these two piglets were also taken to evaluate the calprotectin and neopterin contents. During phase 1, ADG was greater for ZO piglets compared with the CON animals with an intermediate value for the LIGCEL group (P < 0.001). The ADFI was greater for the ZO compared with the CON and LIGCEL treatments (P < 0.003). Piglets in the ZO and LIGNOCELL treatments had less FC than those in the CON group (P < 0.001). During phase 2, only the FC was greater for the ZO and LIGCEL treatments compared with CON animals (P < 0.013). During phase 3, growth performances were not affected by the dietary treatments. For the entire experiment, ZO piglets had greater ADG than those in the CON group with an intermediate value for LIGCEL treatment (P < 0.019). D-lactate decreased from d 6 to 13 while DAO increased (P < 0.001). The DAO was also greater for ZO and LIGCELL piglets compared with CON animals (P < 0.001). Neopterin was greater for ZO treatment but only on d 13 (Trt × day, P < 0.010). Finally, calprotectin decreased from d 6 to 13 (P < 0.001) but was not affected by dietary treatments. In conclusion, ZO and LIGCEL fiber act positively on growth by modulating markers of intestinal inflammation. LIGCEL fiber could, therefore, be an alternative to ZO in the diet of weaned piglets.

Experimental assessment of oxy-CO2 gasification strategy with woody biomass

This paper presents the results obtained during an extensive experimental campaign focused on analysing the application of Oxy-CO2 gasification technology to a small downdraft gasifier fed with woody biomass. Oxy-gasification enables the production of a nitrogen-free synthesis gas (syngas), which can be effectively employed in the synthesis of various high-value chemicals, including but not limited to synthetic natural gas (SNG), methanol (CH3OH), ammonia (NH3), hydrogen and more.The gasifier performances were analysed using different CO2/O2 ratios in the feed (between 1 and 3 kg/kg). The inlet biomass flow rate was approximately 12–18 kg/h, while the equivalence ratio ranged between 19 % and 26 %. The results show that the gasifier can produce a syngas flow rate in the range of 15–25 Nm3/h with a lower heating value (LHV) of between 8 and 10 MJ/Nm3 and a cold gas efficiency of up to 78 %. The operative behaviour of the gasification system is stable and simple to control.

Taurine-mediated gene transcription and cell membrane permeability reinforced co-production of bioethanol and Monascus azaphilone pigments for a newly isolated Monascus purpureus

BackgroundTaurine, a semi-essential micronutrient, could be utilized as a sulfur source for some bacteria; however, little is known about its effect on the accumulation of fermentation products. Here, it investigated the effect of taurine on co-production of bioethanol and Monascus azaphilone pigments (MonAzPs) for a fungus.ResultsA newly isolated fungus of 98.92% identity with Monascus purpureus co-produced 23.43 g/L bioethanol and 66.12, 78.01 and 62.37 U/mL red, yellow and orange MonAzPs for 3 d in synthetic medium (SM). Taurine enhanced bioethanol titer, ethanol productivity and ethanol yield at the maximum by 1.56, 1.58 and 1.60 times than those of the control in corn stover hydrolysates (CSH), and red, yellow and orange MonAzPs were raised by 1.24, 1.26 and 1.29 times, respectively. Taurine was consumed extremely small quantities for M. purpureus and its promotional effect was not universal for the other two biorefinery fermenting strains. Taurine intensified the gene transcription of glycolysis (glucokinase, phosphoglycerate mutase, enolase and alcohol dehydrogenase) and MonAzPs biosynthesis (serine hydrolases, C-11-ketoreductase, FAD-dependent monooxygenase, 4-O-acyltransferase, deacetylase, NAD(P)H-dependent oxidoredutase, FAD-dependent oxidoredutase, enoyl reductase and fatty acid synthase) through de novo RNA-Seq assays. Furthermore, taurine improved cell membrane permeability through changing cell membrane structure by microscopic imaging assays.ConclusionsTaurine reinforced co-production of bioethanol and MonAzPs by increasing gene transcription level and cell membrane permeability for M. purpureus. This work would offer an innovative, efficient and taurine-based co-production system for mass accumulation of the value-added biofuels and biochemicals from lignocellulosic biomass.

Framework for a savanna burning emissions abatement methodology applicable to fire-prone miombo woodlands in southern Africa

Background and aims To assess development of a robust emissions accounting framework for expansive miombo woodland savannas covering ~2 million  km2 of southern Africa that typically are burnt under relatively severe late dry season (LDS) conditions. Methods A detailed site-based study of fuel accumulation, combustion and greenhouse gas (GHG) emission factor parameters under early dry season (EDS) and LDS conditions along a central rainfall-productivity and associated miombo vegetation structural and floristics gradient, from lower rainfallsites in northern Botswana to higher rainfall sites in northern Zambia. Key results Assembled field data inform core components of the proposed emissions reduction framework: fuel and combustion conditions sampled across the vegetation/productivity gradient can be represented by three defined Vegetation Fuel Types (VFTs); fuel accumulation, combustion and emissions parameters are presented for these. Applying this framework for an illustrative case, GHG emissions (t CO2-e) from EDS fires were one-third to half those of LDS fires per unit area in eligible miombo VFTs. Conclusions Our accounting framework supports undertaking EDS fire management to significantly reduce emissions and, realistically, burnt extent at landscape scales. We consider application of presented data to development of formal emissions abatement accounting methods, linkages with potential complementary woody biomass and soil organic carbon sequestration approaches, and necessary caveats concerning implementation issues.

Strategy for the analysis of lignocellulosic biomass to select a viable transformation route in the Colombian context.

Lignocellulosic biomass is widely available in the world. However, a consensus has yet to be established to evaluate the biomass valorization alternatives. The chemical composition is the primary technical limitation in selecting a transformation route to obtain value-added products. In this paper, the bagasse from non-centrifuged sugar (NCS) production and Pinus patula (PP) wood chips were analyzed in terms of complete chemical composition to establish their potential for selecting the transformation routes. A strategy to select the best route based on the chemical composition was applied and a feedstock criteria model was proposed. Schemes were obtained and compared using a bioprocess selection strategy proposed in previous works. As a result, the preliminary biorefinery schemes were finally defined. The assessment of schemes derived from the outlined strategy included technical, economic, environmental, and social analyses. The environmental evaluation was complemented with a geolocation assessment, revealing a 0.75-ton CO2-eq/yr contribution to the carbon footprint for local distribution. The sustainability index for the PP biorefinery and the bagasse from NCS production was analyzed, resulting in indices of 44.8 and 60.9, respectively. These values were primarily derived from the economic and environmental analyses of both processes.