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The aim of this work was to optimizes a biorefinery process for the conversion of mixed hydrolyzates from agro-industrial by-products into high oleic Single Cell Oils (SCOs), a versatile platform for the production of many bio-based chemicals. In particular, the specific objective was to convert undetoxified wheat straw hydrolyzates in triglycerides by the oleaginous yeast Yarrowia lipolytica ATCC 46483. To this scope, the lignocellulosic biomass was fractionated by a steam-explosion process into its constitutive macromolecules, namely cellulose, hemicellulose and lignin. Process strategies were optimized to produce concentrated hydrolyzates containing both C6 and C5 sugars that were used as growth medium for the lipids production., Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 509-511

Inulin is a reserve carbohydrate accumulated in the roots and tubers of many plants belonging mainly to the Asteraceae family, including Cardoon (Cynara cardunculus L.). The hydrolysis of inulin allows to obtain fructose, a starting monomer to obtain key molecules for biobased platforms for the production of biomaterials and renewable biofuels. The use of acidic agents in the hydrolysis process is unfavorable from an environmental point of view and is corrosive for industrial plants, therefore the research turns its attention to enzymatic hydrolysis. The enzymes used for this purpose are called inulinases and have the disadvantage of being expensive, so a strategy that can be used to make the process more cost-effective is to reuse the enzyme by immobilizing it. The aim of the present work was to maximize the fructose yield from cardoon by using immobilized inulinase on epoxy media. The results showed a conversion yield of 87% after the treatment of inulin batches, allowing to save about three-fold enzyme compared to free-inulinase methods., Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 505-508

Lignocellulosic biomass, including both herbaceous and woody feedstock, is currently widely used in many biorefineries. The lignin fraction (20-35 %DRY) is typically thermochemically converted into the cogeneration section of the biorefinery to produce heat and electricity. However, lignin holds a greater potential in several industrial sectors to produce biobased materials and several chemical building blocks. In particular, novel technologies allow obtaining low molecular weight compounds, such as aromatic or hydrocarbons. In this work, a mathematical methodology was developed to evaluate the best option in terms of lignin valorization. A process superstructure was built to compare alternative process pathways from lignocellulosic biomass. The following conversion options were considered: jet-fuels (JF), phenol-formaldehyde resins (PFR), polyurethane foams (PUF), and syngas for green electricity generation. By AIMMS optimization software, a Mixed Integer Linear Programming (MILP) was applied to obtain a simplified mathematical analysis and, consequently, the maximum lignin cost maximization for each lignin valorization process. In particular, process conversion, required utilities, product values were assessed for each process technology. Preliminary results show that the production of phenol-formaldehyde resins is the process closer to the market uptake. On the other side, polyurethane and jet-fuels appear still far from the market and their production would be feasible at a polyurethane foams and jet-fuel selling price at 300 % of the current selling price.

Second generation sugars represent a versatile platform for the production of both biofuels and chemicals. Both costs and ready availability of well balanced cellulase preparations are among the major constraints in the enzymatic saccharification yet. Solid state fermentation (SSF), using agro-industrial residues as substrates, offers a big potential for the containment of the cellulase production costs. In this research work, artichoke thistle (Cynara cardunculus), a perennial herbaceous Mediterranean species has been evaluated as a low cost substrate for the production of both cellulases and sugar hydrolysates. Results from this study showed that C. cardunculus spent biomass represents an optimal low cost substrate for the solid-state production of cellulolytic enzymes from A. tubingensis. The optimized use of this enzymatic cocktail enabled the attainment of hydrolysis yields that did not differ significantly from those obtained with benchmark commercial enzymes. © 2018 ETA-Florence Renewable Energies.

The use of renewable sources for the production of energy and products is a pillar of the bio-based circular economy. The present paper describes the use of Cardoon (Cynara cardunculus L.) as a sustainable feedstock for the production of second generation sugars. The residual lignocellulosic fraction of the plant contains 37% C6 and 16% C5. The exploitation of the plant carbohydrates for the production of chemicals represents one of the main targets of the research activities of the Italian projects REBIOCHEM (cluster SPRING). As part of this research program, the present work describes the acid and base-catalyzed steam explosion pretreatments of the lignocellulosic residue of cardoon. The influence of temperature, catalysts concentration, and treatment time was studied using the response surface methodology. The results indicated that the addition of different catalysts determined different extents of biomass fractionation which can be suitable for different biorefining schemes. Optimized experimental setups were achieved for each catalyst tested by using the full factorial design (ANOVA). Results showed that sulphuric acid catalysis yielded the highest cellulose enzymatic hydrolyzability (~90%) while base catalyst reduced the lignin content in the solid fibers and a significant decrease of inhibitors in the liquid fraction., Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 1217-1220

The IEA Bioenergy Task 42 “Biorefining” with its 11 member countries (A, AUS, CA, DK, G, I, IR, J, NL, NZ, USA) has the following definition on biorefining: “Biorefining is the sustainable processing of biomass into a spectrum of bio-based products (food, feed, chemicals, and materials) and bioenergy (biofuels, power and/or heat)”. Based on the activities in the 11 member countries of Task 42 the assessment framework is developed based on a life cycle basis to cover all relevant issues from the production, operation and end of life phase of the whole value chain of various biorefineries. The framework follows the following hierarchy procedure: 1) biorefinery classification and assessment of the technologies and processes using the 9 levels of the “Technology Readiness Level (TRL)”. 2) Calculation of most relevant economic data using the approach of Life Cycle Costing (LCC). 3) Application of Life Cycle Assessment (LCA) to assess the most relevant environmental aspects. 4) Screening of relevant social issues in a Social Life Cycle Assessment (sLCA). 5) Integration of these aspects in the approach of Life Cycle Sustainability Assessment (LCSA) 6) Identification of most attractive industry sectors (“Hot Spots”) for the integration of biorefineries in the existing industrial infrastructure 7) Highlighting necessary R&D demand for commercialization until 2025, 8) Concluding on the possible future role in a BioEconomy in a regional, national and international context. A compact format is developed to present the results of the assessing framework. The framework is applied to different biorefinery concepts. The results assist various stakeholders in finding their position on biorefining in a future biobased economy while minimizing unexpected technical, economic and financial risks by significantly contributing to the development of a BioEconomy., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 1353-1358

Sugars from biomass represent a versatile platform for the production of a number of bio-based products. Cellulases enzymes play an important role as they can hydrolyse biomass at mild conditions. Cellulases are mostly produced from Trichoderma and Aspergillus fungi. Although less investigated, another fungus, Acremonium cellulolyticus produces effective cellulases for the conversion of lignocellullosic substrates. The present paper describes the conversion of corn stover steam pretreated by Acremonium enzymes. The performaces of the Acremonium cellulases were compared with commercial Trichoderma and Aspergillus blends (Celluclast and Novozyme). The results indicated that, at the same process conditions, Acremonium cellulases were more effective and yielded 20% more sugars than the reference blends. Furthermore, the addition of external hemicellulases (Multifect xylanase) to the Acremonium complex produced a xylan hydrolysis 20% higher than that produced by the addition of the same amount to the reference mixtures. These findings indicated an higher synergistic action of the enzymatic components in the Acremonium complex with the commercial hemicellulases mixtures. In order to prolong the enzymes life time during the enzymatic hydrolysis with the Acremonium complex, three additives, namely Tween 80, Tween 20 and BSA, were tested to reduce the unspecific enzymes adsorption. The residual enzymatic activities in the hydrolysates were monitored during the hydrolysis and the results compared with control systems. The findings indicated that the use of Tween 80 and Tween 20 were effective in reducing the adsorption of the cellobiose hydrolases., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 1332-1335

A key driver for the necessary sustainable development is the implementation of the BioEconomy, which is based on renewable resources to satisfy its energy and material demand of our society. The broad spectrum of biomass resources offers great opportunities for a comprehensive product portfolio to satisfy the different needs of a BioEconomy. The concept of biorefining guarantees the resource and energy efficient use of biomass resources. The IEA Bioenergy Task 42 “Biorefining” has the following definition on biorefinery: “Biorefining is the sustainable processing of biomass into a spectrum of bio­based products (food, feed, chemicals, and materials) and bioenergy (biofuels, power and/or heat)”. Currently many different biorefinery concepts are developed and already implemented which play a key role in establishing a BioEconomy. The purpose of the work is to provide facts and figures on different biorefinery systems and their efficient integration in existing industrial infrastructure. This information assists industry, decision makers and investors in their strategies to invest and integrate resource efficient biomass uses in the infrastructure of a future BioEconomy. Based on the activities of the 11 participating countries (A, AUS, CA, DK, FR, G, I, J, NL, US) the IEA Task 42 identified and assessed the current status and development potential of “energy­driven” biorefineries and “product­driven” biorefineries. The 14 most interesting “energy­driven” biorefinery concepts until 2025 and their value chains, including the integration and deployment options in industrial infrastructures, are analyzed. Based on the developed “Biorefinery Fact Sheet” for the most relevant biorefineries the sustainable and efficient integration of biorefineries in existing and future infrastructure is examined. The possible role of biorefineries in a BioEconomy is analyzed in a regional, national and international context. The classification and description of existing infrastructure in combination with the available biomass resources and (future) market needs shows the matching points for a resource efficient roll out of the BioEconomy by implementing various biorefineries. Examples for identified “hot spots” by coproducing high value products like food, feed, biochemicals and biomaterials are: 1) pulp&paper and wood industry to additionally produce transportation biofuels and biochemicals; 2) food&feed industry to additionally produce bioenergy carriers, 2) chemical industry to integrate biogenic resources to produce biobased chemicals. The results assist various stakeholders in finding their position on biorefining in a future biobased economy while minimizing unexpected technical, economic and financial risks., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 1480-1485

Biomass-derived sugars are platform molecules that can be used for a number of applications. In the biofuels-driven biorefineries, C6 sugars can be fermented to ethanol or butanol. C5 sugars can also be fermented by means of genetically modified microorganisms able to withstand at industrially relevant conditions. As alternative, they can be converted to chemicals, such as furfural, which is considered a platform molecule for the synthesis of numerous products. In the present paper two Arundo donax biorefining options are presented: the production of mixed hydrolyzates for alcoholic fermentation; the separate conversion of C6 and C5 sugars to ethanol and furfural (FA) respectively. Acid-catalysed steam explosion was used for biomass pretreatment and fractionation. A number of process conditions were tested for achieving the highest ethanol concentration and the highest xylose conversion at mild conditions. In particular, hemicellulose derived xylose was dehydrated to furfural in biphasic media by microwave energy. Amberlyst 15 was used as solid acid catalyst. The results indicate that after 10 minutes of microwave heating at 150°C the conversion of xylose to furfural was around 48% of the theoretical value. Part of the research presented in the present paper was funded by the European Project Biolyfe., Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 1099-1103

IEA Bioenergy Task 42 „Biorefining“ has the following definition on biorefinery: “Biorefining is the sustainable processing of biomass into a spectrum of bio-based products (food, feed, chemicals, materials) and bioenergy (biofuels, power and/or heat)”. Currently many different and various biorefinery concepts are developed and are already implemented. Based on the activities of the 12 participating countries (A, AUS, CA, DK, FR, G, I, IR, J, K, NL, US) the task identifies and assesses the current status and development potential of “energy-driven” biorefineries and “product-driven” biorefineries. The assessments are based on a “Full Value Chain Approach”, covering raw material issues, conversion processes and final product use in an integrated approach and assessing economic, socio-economic, environmental and social aspects in comparison to conventional processes and products. As a first step the 15 most interesting “energy-driven” biorefinery concepts until 2025 and their value chains, including the integration and deployment options in industrial infrastructures, are analyzed. As the development status and the perspectives for implementation and development of these energy driven biorefineries are different the IEA task develops a “Biorefinery Fact Sheet” for the uniform description of the key facts of a Based on a technical description and the classification scheme the mass and energy balance is calculated for the most reasonable production capacity for each of the selected biorefineries. Then the three dimensions – economic, environmental and social -of sustainability are assessed for each biorefinery and documented in a compact form in the “Biorefinery Fact Sheet”. Based on these sheets an easy comparison of the different biorefinery systems is possible. The “Biorefinery Fact Sheet” assists various stakeholders in finding their position on biorefining in a future biobased economy. The “Biorefinery Fact Sheets” will be made for the 15 most interesting “energy driven biorefinery systems” identified by IEA Bioenergy Task 42., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 573-577

Simultaneous saccharification and fermentation (SSF) has been considered the most convenient process strategy for the conversion of biomass sugars into bioethanol. During SSF, temperatures typically lower than 40°C favor both hydrolysis and fermentation. However, the latest enzymatic commercial mixtures with improved performances have optimal working temperatures in the range 45-50°C. In order to conjugate this temperature requirement with the optimal conditions for fermentation, temperature modulation during the process could offer the advantage of discontinuously accelerating the hydrolysis while avoiding sugars accumulation. In the present paper, the effect of an intermittent step-wise increase of temperature along with fed-batch inoculation was investigated during the fermentation of Arundo donax carbohydrates to bioethanol. In particular, temperature was periodically raised to 50° to improve the cellulose conversion and the hydrolyzates were inoculated in fed-batch mode each time the temperature diminished to 32°C.The SSF tests were carried out by using products obtained through the Chemtex technologies for biomass pretreatment and enzymatic liquefaction. The performances of several strains belonging to the families of Saccharomyces cerevisiae, and Kluyveromyces marxianus were compared. The results were discussed in terms of ethanol yields, extent of the cellulose digestion, and microrganisms viability through the process. This work is part of the European project Biolyfe., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 1558-1561

The use of versatile technologies is a key factor in the biorefineries economy because they could ensure a certain flexibility on the final products. Steam explosion can be considered a versatile pretreatment technology since it produces high degrees of biomass destructuration and facilitate fractionation in its macro-components. In the present paper the conversion of steam-pretreated Arundo donax to ethanol and/or furan compounds is presented. In particular, acid-catalyzed dehydration of sugars to furan compounds was carried out by using a microwave-assisted process in a biphasic medium H2O/butanol at different temperatures (120-200°C). The results indicate that, hydrolysis of steam pretreated Arundo donax at high DM content, up to 30%, produced mixed syrups with concentrations of 120-130g/L. A separate processing of the C6 and C5 streams gave 80% of the theoretical ethanol from C6 and 95% of the theoretical 2-furancarbaldehyde from C5. The alternative conversion of the C6 rich fraction into HMF was also explored. The direct dehydration of steam pretreated biomass did not produce a significant conversion of glucose in HMF. A partial saccharification of the biomass up to the liquefaction point, increased the HMF yield up to 17% of soluble glucose. The further enzymatic isomerization of glucose (58%) increased the HMF production up to 64% of the theoretical yield., Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 1065-1069

An important requirement in cost-efficient lignocellulosics-to-ethanol process is to achieve concentrated hydrolyzates. The research in the last years has been focused on improving the enzymes performances in terms of internal dosage of the specific components and increased thermostability. These improved features could facilitate the processing of concentrated biomass suspensions up to 20-30% solids. However, the most important problem in the hydrolysis at high solid loadings is related to the fact that, these suspensions have a strong non-Newtonian behavior with high viscosities values that cause mixing and mass transfer limitations, and, presumably increased inhibition by intermediates. In this paper preliminary results from the rheological characterization of concentrated biomass suspensions are presented with the scope of gaining data for the process design and optimization. In particular various geometries have been evaluated for the rheological characterizations of these fluids (namely vane, plate/plate, cone/plate), and several tests were done to measure the viscosity, the, the consistency and fluidity index under different process conditions.., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 1681-1684

An efficient production of ethanol from lignocellulosic hydrolyzates requires the use of microorganisms capable to convert both glucose and xylose sugars with high yields. One approach to achieve this target is the use of yeast co¬cultures, formed by Pichia stipitis, renamed Scheffersomyces stipitis, and Saccharomyces cerevisiae species, which are characterized by different metabolic activities. In this context, numerous parameters, such as temperature, pH and oxygen requirements are critical factors in the fermentation process and, among these, aeration is very important because of its influence on xylose conversion. In this work, ethanol production from Arundo Donax hydrolyzates was evaluated in a stirred tank bioreactor using co-cultures of Schef. stipitis and S. cerevisiae strains. Experimental tests were performed at different values of aeration, providing different volumetric oxygen transfer coefficient (KLa) and using activated charcoal to reduce the inhibitors toxic effect., Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 1709-1712

The IEA Bioenergy Task 42 „Biorefineries“ made the following definition on biorefinery: “Biorefining is the sustainable processing of biomass into a spectrum of bio­based products (food, feed, chemicals, materials) and bioenergy (biofuels, power and/or heat)”. “Energy­driven” biorefineries and “product­driven” biorefineries are distinguished. Based on the ongoing activities in the 12 countries (A, AUS, CA, DK, FR, G, I, IR, NL, T, UK, US) participating in Task 42, the task identifies and assesses the current status and development potential of both “energy­driven” biorefineries (incl. biofuels) and “product­driven” biorefineries. These assessments are based on a “Full Value Chain approach”, covering raw material issues, conversion processes and final product applications in an integrated approach. As a first step the 15 most interesting “energy­driven” biorefinery concepts until 2020 and their value chains, including the integration and deployment options in existing industrial infrastructures, are analysed. These concepts produce the following transportation biofuels: biodiesel, bioethanol, FT­biofuels, biomethane from upgraded biogas and SNG (synthetic natural gas) with the following feedstocks: oil crops, oil residues, sugar and starch crops, wood chips, straw, grass, saw mill residues, (sulfite) liquor, algae. The Task 42 is assessing the sustainability of these concepts by analysing economic, environmental and social aspects in comparison to conventional processes and products., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1075-1079

Arundo donax is a non edible biomass that can be used for energetic purposes thanks to the low inputs required for its growth. Biomass pretreatment was investigated by using the ENEA’s steam explosion (SE) batch plant. The temperatures were ranged from 196 up 210 °C and the treatment time was 5 minutes. At these conditions the products obtained appeared poor pupled as confirmed by the characterization of the water soluble fractions. Further optimizations were done by impregnating the biomass with small amounts of acids prior to the pretreatment. The acid catalyzed SE pretreatment produced products much more pulped that can be easily fractionated. On the whole, higher amounts of hemicellulose sugars were separated in the liquid fractions already as monomers. In the present paper, the effectiveness of the SE pretreatments with and without acid was discussed in terms of the relevant enzymatic hydrolizability. The results of the conventional SE conditions were then compared with those obtained by testing materials pretreated by the Chemtex technology as part of the European project BIOLYFE., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 2181-2184

Lignocellulosic materials can be used to produce bioethanol. The enzymatic hydrolysis of cellulose is catalyzed by cellulases, a complex system of enzymes that work together synergistically to attack native cellulose releasing glucose and soluble carbohydrates. Generally, these enzymes have low thermal stability and it is quite arduous to recover them from the hydrolyzates for the use in successive batches. Immobilization of cellulases may improve their performances. In the present paper, an epoxy support (Sepabeads® EC­EP403/S) was used as enzymes carrier for the cellulases immobilization. The innovative aspect of this work is the use of this particular support to perform a very easy immobilization­stabilization of commercial cellulase enzymes. The highest immobilization rate was obtained at alkaline conditions (pH 8) and it was promoted by long­term incubation of enzymes in the mixture containing the epoxy support and buffer. The presence of support reduced the chemical deactivation of the enzymes due to the pH of the immobilization procedure. The overall efficiency of the cellulase immobilization was 70%., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 1756-1758

For several years, international research has been performing the optimization of cellulose enzymatic hydrolysis to produce bioethanol. Enzymes low specific activity and fast deactivation are relevant problems in the development of this process and additional improvements are needed to make bioethanol comparable to traditional fuels. Enzymes immobilization facilitates biocatalyst recovery and reuse. Furthermore, enzymes immobilization avoids autolysis and increase enzyme stability allowing continuous operation for long periods, reducing processes costs and making this process more suitable to industrial scale up. In this paper, commercial cellulase enzymes (Celluclast 1.5 and Novozym 188) immobilization on epoxy Sepabeads® has been investigated. These supports ensure a mild physical adsorption of the enzymes followed by a very fast intramolecular covalent binding with the material epoxy groups. Data show that 60% of loaded Celluclast proteins were adsorbed by the support and that more than 90% of these proteins remained stably linked even after repeated washings. Similar results were obtained with Novozym. Novozym enzyme immobilized was used for ß-glucosidase activity test. The first analyses show that immobilized Novozym activity is comparable with free enzyme. The paper shows preliminary results about immobilized biocatalysts performances., Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 1440-1442

Kraft lignin conversion to value-added products is an alternative way to manage the main pulp and paper secondary stream thus contributing to reducing avoid greenhouse gas emissions compared to equivalent fossil-based processes. Process simulation and integration can help to identify the most promising pathways and increase the profitability of the process. This work presents results of a comparison between the process optimization of two different potential products that were modeled and analyzed. Aromatic monomers and phenol-formaldehyde resins were considered as possible products by means of alternative process pathways, including hydrothermal liquefaction, hydrodeoxygenation, pyrolysis, dissolution with deep eutectic solvents, hot water extraction, and resin synthesis. Mixed-integer nonlinear programming was applied to optimize the superstructure and obtain the maximum lignin cost. A sensitivity analysis in terms of the final products selling price was performed to consider the market variability. Minimum selling prices of aromatic monomers and phenol-formaldehyde resins for a feasible lignin process were calculated. Maximum lignin cost larger than 100 €/t resulted acceptable only for phenol-formaldehyde resins selling price larger than 0.6 €/kg or for AM selling price larger than 1.80 €/kg. Aromatic monomers turned out to be the optimal product if its selling price is larger 1.20 €/kg and the phenol-formaldehyde resins cost is lower than or equal to 0.6 €/kg. Higher phenol-formaldehyde resins selling prices make this product more convenient.

Single cell oil (SCO) represents an outstanding alternative to both fossil sources and vegetable oils from food crops waste. In this work, an innovative two-step process for the conversion of cellulosic paper mill waste into SCO was proposed and optimised. Hydrolysates containing glucose and xylose were produced by enzymatic hydrolysis of the untreated waste. Under the optimised reaction conditions (Cellic® CTec2 25 FPU/g glucan, 48 h, biomass loading 20 g/L), glucose and xylose yields of 95 mol% were reached. The undetoxified hydrolysate was adopted as substrate for a batch-mode fermentation by the oleaginous yeast Lipomyces starkeyi. Lipid yield, content for single cell, production and maximum oil productivity were 20.2 wt%, 37 wt%, 3.7 g/L and 2.0 g/L/d respectively. This new generation oil, obtained from a negative value industrial waste, represents a promising platform chemical for the production of biodiesel, biosurfactants, animal feed and biobased plastics.

The present investigation aims at exploring the application of low-cost catalysts based on smectitic clays to the hydrodeoxygenation (HDO) of Cynara cardunculus derived lignin. Two types of clay minerals, montmorillonite and saponite, are pillared and decorated with suitable metals by means of an optimized process and characterized by X-ray powder diffraction (XRPD), porosity, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), UV–vis–NIR, Raman, and thermogravimetric analysis (TGA). Alkaline lignin is obtained from steam-treated cardoon. Lignin depolymerization is conducted in a bench-scale apparatus under subcritical conditions, at relatively low temperature (320 °C), for 3 h, under 5-6 MPa of total pressure. Four catalysts are tested, namely, Fe/Al-pillared montmorillonite (FAMO) and saponite (FASA), and Ni-exchanged Ni/Al-pillared montmorillonite (Ni–Ni/AMO) and saponite (Ni–Ni/ASA). Results indicate that mineral clay–based catalysts result effectively in the hydrogenolysis of lignin, producing several low molecular weight aromatics and other species, with overall conversions in the range 60–70%. Montmorillonite-based catalysts yield the highest substrate conversion, with a prevalence of phenols and substituted phenols, whereas only Ni–Ni/ASA generates a higher abundance of aliphatic hydrocarbons. Overall, data indicate that smectitic clays are promising catalyst supports for products-oriented HDO of lignin.

Biomass-derived sugars are platform molecules that can be converted into a variety of final products. Non-food, lignocellulosic feedstocks, such as agroforest residues and low inputs, high yield crops, are attractive bioresources for the production of second-generation sugars. Biorefining schemes based on the use of versatile technologies that operate at mild conditions contribute to the sustainability of the bio-based products. The present work describes the conversion of giant reed (Arundo donax), a non-food crop, to ethanol and furfural (FA). A sulphuric-acid-catalyzed steam explosion was used for the biomass pretreatment and fractionation. A hybrid process was optimized for the hydrolysis and fermentation (HSSF) of C6 sugars at high gravity conditions consisting of a biomass pre-liquefaction followed by simultaneous saccharification and fermentation with a step-wise temperature program and multiple inoculations. Hemicellulose derived xylose was dehydrated to furfural on the solid acid catalyst in biphasic media irradiated by microwave energy. The results indicate that the optimized HSSF process produced ethanol titers in the range 43&ndash, 51 g/L depending on the enzymatic dosage, about 13&ndash, 21 g/L higher than unoptimized conditions. An optimal liquefaction time before saccharification and fermentation tests (SSF) was 10 h by using 34 filter paper unit (FPU)/g glucan of Cellic&reg, CTec3. C5 streams yielded 33.5% FA of the theoretical value after 10 min of microwave heating at 157 &deg, C and a catalyst concentration of 14 meq per g of xylose.

Wheat straw is an abundant source of lignocellulosic biomass that is generally not utilized for biofuel production, nor for other uses. Recent EU renewable energy directive fosters bioethanol production through lignocellulosic sugars fermentation, but the cost of this process is an issue that often depends on biomass characteristics. Lignin is a class of three-dimensional polymers providing structural integrity of plant tissues. Its complex structure, together with hemicelluloses and uronic acids content, could affect the ability of hydrolyzing biomass to fermentable sugars. To get insights into this variation, a set of 10 durum wheat genotypes was analyzed to determine variation of straw digestibility to fermentable sugars. The results showed that the lignin content was the major factor determining the recalcitrance to enzymatic process. The analysis of Spearman’s correlation indicated that the sugar released after enzymatic hydrolysis had a negative connection with the lignin content, while it was positively correlated with the culm length. The possible role of other cell wall components, such as arabinose and uronic acids, was also discussed. This work aimed at analyzing the diversity of lignocellulosic digestibility to fermentable sugars of wheat straw in a small germplasm collection. Some of the selected genotypes were characterized by high sugars digestibility and high grain yield, characteristics that could make biorefining of wheat straw profitable.

The production of seed oils from Cynara cardunculus generates huge amounts of lignocellulosic residues which can be exploited according to a cascade approach. In this paper, residual cardoon biomass (RCB) was tested as a growth substrate for the solid-state production of cellulolytic cocktails by species known to produce glucose-tolerant β-glucosidase isoenzymes. Best productions were obtained with 10-d-old Aspergillus tubingensis cultures on RCB supplemented with wheat bran (200 g kg−1) yielding β-glucosidase and endo-β-1,4-glucanase activities as high as (25 and 4) IU g−1, respectively, and 4 FPU g−1. The saccharification performance of the obtained cocktail tested on acid-catalysed steam-exploded RCB at low solid loading (25 g dm−3) was around 53% at 20 FPU g−1 cellulose. These performance were significantly enhanced by adding the xylanase-rich NS 22083 commercial formulation, reaching glucose yields higher than 80% after 72 h incubation. The use of the catalytic additive was optimized by a statistical approach, based on factorial analysis. A comparison of the performance of the A. tubingensis reinforced cocktail with the Cellic®CTec2 taken as benchmark formulation was done at the same enzyme load and performed at industrially relevant solid loadings, namely at (100 and 200) g dm−3. This comparison showed that Cellic®CTec2 led to only slightly higher glucose yields while an opposite outcome was observed for xylose yields, irrespective of the solid loading conditions. Thus, this study shows that an in-house enzyme production, based on the solid-state conversion of an industrial byproduct, able of yielding cellulolytic cocktails with substantial saccharification performance is feasible.

A hybrid system based on lignocellulosic biomass gasification and syngas fermentation represents a second-generation biorefinery approach that is currently in the development phase. Lignocellulosic biomass can be gasified to produce syngas, which is a gas mixture consisting mainly of H2, CO, and CO2. The major challenge of biomass gasification is the syngas’s final quality. Consequently, the development of effective syngas clean-up technologies has gained increased interest in recent years. Furthermore, the bioconversion of syngas components has been intensively studied using acetogenic bacteria and their Wood–Ljungdahl pathway to produce, among others, acetate, ethanol, butyrate, butanol, caproate, hexanol, 2,3-butanediol, and lactate. Nowadays, syngas fermentation appears to be a promising alternative for producing commodity chemicals in comparison to fossil-based processes. Research studies on syngas fermentation have been focused on process design and optimization, investigating the medium composition, operating parameters, and bioreactor design. Moreover, metabolic engineering efforts have been made to develop genetically modified strains with improved production. In 2018, for the first time, a syngas fermentation pilot plant from biomass gasification was built by LanzaTech Inc. in cooperation with Aemetis, Inc. Future research will focus on coupling syngas fermentation with additional bioprocesses and/or on identifying new non-acetogenic microorganisms to produce high-value chemicals beyond acetate and ethanol.

A two-step exploitation of the giant reed cellulose to glucose and levulinic acid, after the complete removal of the hemicellulose fraction, was investigated using FeCl3 as catalyst. In the first step, the microwave-assisted hydrolysis of cellulose to glucose was optimised by response surface methodology analysis, considering the effect of temperature, reaction time and catalyst amount. Under the optimised reaction conditions, the glucose yield was 39.9 mol%. The cellulose-rich residue was also converted by enzymatic hydrolysis, achieving the glucose yield of 39.8 mol%. The exhausted residue deriving from the chemical hydrolysis was further converted to levulinic acid by microwave treatment at harsher reaction conditions. The maximum levulinic acid yield was 64.3 mol%. On the whole, this cascade approach ensured an extensive and sustainable exploitation of the C6 carbohydrates to glucose and levulinic acid, corresponding to about 70 mol% of glucan converted to these valuable bioproducts in the two steps.

Lignocellulosic biomass represents one of the most important feedstocks for future biorefineries, being a precursor of valuable bio-products, obtainable through both chemical and biological conversion routes. Lignocellulosic biomass has a complex matrix, which requires the careful development of multi-step approaches for its complete exploitation to value-added compounds. Based on this perspective, the present work focuses on the valorization of hemicellulose and cellulose fractionsof giant reed (Arundo donax L.) to give second-generation sugars, minimizing the formation of reaction by-products. The conversion of hemicellulose to xylose was undertaken in the presence of the heterogeneous acid catalyst Amberlyst-70 under microwave irradiation. The effect of the main reaction parameters, such as temperature, reaction time, catalyst, and biomass loadings on sugars yield was studied, developing a high gravity approach. Under the optimised reaction conditions (17 wt% Arundo donax L. loading, 160 &deg, C, Amberlyst-70/Arundo donax L. weight ratio 0.2 wt/wt), the xylose yield was 96.3 mol%. In the second step, the cellulose-rich solid residue was exploited through the chemical or enzymatic route, obtaining glucose yields of32.5 and56.2 mol%, respectively. This work proves the efficiency of this innovative combination of chemical and biological catalytic approaches, for the selective conversion of hemicellulose and cellulose fractions of Arundo donax L. to versatile platform products.

Market implementation of integrated biorefinery requires reliable and advanced processing units combined with eco-friendly and economically profitable production chains. Future developments of integrated biorefinery systems should include either crop cultivation with selected genotypes that maximize full chain performances either the increasing use of disposable or/and underused biomass. The aim of this paper was to review the main biorefining opportunities related to agro-bioenergy co-products and agroindustrial residues potentially available on the World (as biofuel co/by-products, agricultural residues, agricultural by-products and agro-wastes), paying a special attention to high-value added products associated to some emerging markets. The current status and future perspectives of conversion from agro-bioenergy residual biomass into high-value bio-based products by innovative biorefineries have been considered. After a brief recognition on the nature and origin of the main categories of organic residuals derived from the biofuel chains and agricultural, forestry, food processing and animal activities within definitions given by the European Union, this paper has firstly focused its choice on the high-value added products associated to some chemical basic-platforms (succinic acid, cellulose, glycerin, proteins, peptides, enzymes, etc.). A special attention has also been done to high-value added bio-based products and commodities related to sustainable and renewable farming systems (soil amendment, phytosanitary drug, plant biostimulant and biofertilizer) and bio-based industries in producing innovative biomaterials (bioplastic, lignin and alginate). Finally, this paper has addressed own concern on the perspectives of integrated biorefining from organic residuals drawing particular attention to the European and Italian contexts giving and discussing some new opportunities for big players and stakeholders. © 2018 Elsevier Ltd

Background: Some lignocellulosic biomass feedstocks occur in Mediterranean Countries. They are still largely unexploited and cause considerable problems due to the lack of cost-effective harvesting, storage and disposal technologies. Recent studies found that some basidiomycetous yeasts are able to accumulate high amount of intracellular lipids for biorefinery processes (i.e., biofuels and biochemicals). Accordingly, the above biomass feedstocks could be used as carbon sources (after their pre-treatment and hydrolysis) for lipid accumulation by oleaginous yeasts. Results: Cardoon stalks, stranded driftwood and olive tree pruning residues were pre-treated with steam-explosion and enzymatic hydrolysis for releasing free mono- and oligosaccharides. Lipid accumulation tests were performed at two temperatures (20 and 25 °C) using Leucosporidium creatinivorum DBVPG 4794, Naganishia adeliensis DBVPG 5195 and Solicoccozyma terricola DBVPG 5870. S. terricola grown on cardoon stalks at 20 °C exhibited the highest lipid production (13.20 g/l), a lipid yield (28.95%) close to the maximum theoretical value and a lipid composition similar to that found in palm oil. On the contrary, N. adeliensis grown on stranded driftwood and olive tree pruning residues exhibited a lipid composition similar to those of olive and almonds oils. A predictive evaluation of the physical properties of the potential biodiesel obtainable by lipids produced by tested yeast strains has been reported and discussed. Conclusions: Lipids produced by some basidiomycetous yeasts grown on Mediterranean lignocellulosic biomass feedstocks could be used as supplementary sources of oils for producing biofuels and biochemicals. © 2018 The Author(s).

Agricultural by-products such as corn stover are considered strategic raw materials for the production of second-generation bioethanol from renewable and non-food sources. This paper describes the conversion of steam-pretreated corn stover to ethanol utilising a multi-step process including enzymatic hydrolysis, isomerisation, and fermentation of mixed hydrolysates with native Saccharomyces cerevisiae. An immobilised isomerase enzyme was used for the xylose isomerisation along with high concentrations of S. cerevisiae. The objective was to assess the extent of simultaneity of the various conversion steps, through a detailed analysis of process time courses, and to test this process scheme for the conversion of lignocellulosic hydrolysates containing several inhibitors of the isomerase enzyme (e.g. metal ions, xylitol and glycerol).The process was tested on two types of hydrolysate after acid-catalysed steam pretreatment: (a) the water soluble fraction (WSF) in which xylose was the largest carbon source and (b) the entire slurry, containing both cellulose and hemicellulose carbohydrates, in which glucose predominated.The results indicated that the ethanol concentration rose when the inoculum concentration was increased in the range 10-75g/L. However, when xylose was the largest carbon source, the metabolic yields were higher than 0.51gethanol/gconsumed sugars probably due to the use of yeast internal cellular resources. This phenomenon was not observed in the fermentation of mixed hydrolysates obtained from the entire pretreated product and in which glucose was the largest carbon source. The ethanol yield from biomass suspensions with dry matter (DM) concentrations of 11-12% (w/v) was 70% based on total sugars (glucose, xylose, galactose). The results suggest that xylulose uptake was more effective in mixed hydrolysates containing glucose levels similar to, or higher than, xylose.Analysis of the factors that limit isomerase activity in lignocellulosic hydrolysates excluded any inhibition due to residual calcium ions after the detoxification of the hemicellulose hydrolysates with Ca(OH)2. By contrast, most of the enzyme activity ceased during the fermentation of the entire slurry after steam explosion, probably due to synergistic inhibition effects of various fermentation co-products. © 2014 Elsevier B.V.

Fuel grade bioethanol can be produced from a number of lignocellulosic biomass sources. In the present paper the enzymatic hydrolysis of giant reed (Arundo donax) at high biomass loadings up to 20% (w/v) was investigated. Two pretreatment technologies were used: one step steam explosion (SE) with and without acid catalyst and the novel pilot process from Chemtex consisting in a two steps pretreatment. The results of the biomass composition after different pretreatment conditions along with the corresponding enzymatic hydrolizability at low solids loading, indicated that the best pretreatments were the acid catalyzed steam explosion (ACSE) at 200 °C and the Chemtex process in which the SE step was carried out at 206 for 4. min. Various process configurations, including biomass and enzymes fed-batch, were investigated to avoid excessive viscosities and increase the cellulose conversion. Novel enzymatic preparations from Novozymes, Cellic™ Ctec1 and Cellic™ Ctec2, were used for the biomass saccharification. Concerning the analysis of the factors that limited the hydrolysis yields at high DM content, some evidences indicated that product inhibition by xylooligomers could have an important role. The highest solids loading investigated in the present paper was 21%. Under these conditions and by using an enzymes loading of 0.28. g Ctec2/g glucan, an overall sugars concentration of 91. g/L (glucose. +. xylose) can be obtained after 48. h from ACSE at 200 °C. © 2012 Elsevier Ltd.

Bioethanol can be produced from several biomasses including lignocellulosic materials. Besides 6-carbon sugars that represent the prevalent carbohydrates, some of these feedstocks contain significant amounts of 5-carbon sugars. One common limit of the major part of the xylose-fermenting yeasts is the diauxic shift between the uptake of glucose and xylose during the fermentation of mixed syrups. Thus, optimized fermentation strategies are required.In this paper the ability of Scheffersomyces stipitis strain NRRLY-11544 to ferment mixed syrups with a total sugar concentration in the range 40-80. g/L was investigated by using mono cultures, co-cultures with Saccharomyces cerevisiae strain Bakers Yeast Type II and single cultures immobilized in silica-hydrogel films. The experimental design for the fermentations with immobilized cells included the process analysis in function of two parameters: the fraction of the gel in the broth and the concentration of the cells loaded in the gel. Furthermore, for each total sugars level, the fermentative course of S. stipitis was analyzed at several glucose-to xylose ratios.The results indicated that the use of S. stipitis and S. cerevisiae in free co-cultures ensured faster processes than single cultures of S. stipitis either free or immobilized. However, the rapid production of ethanol by S. cerevisiae inhibited S. stipitis and caused a stuck of the process.Immobilization of S. stipitis in silica-hydrogel increased the relative consumption rate of xylose-to-glucose by 2-6 times depending on the composition of the fermentation medium. Furthermore the films performances appeared stable over three weeks of continuous operations. However, on the whole, the final process yields obtained with the immobilized cells were not meaningfully different from that of the free cells. This was probably due to concurrent fermentations operated by the cells released in the broth. Optimization of the carrier characteristics could improve the performances of the process with immobilized cells. © 2013 Elsevier B.V.

Films of poly(2,3-diaminophenazine) (PDAPh) were obtained on platinum substrates by electropolymerization (cyclic voltammetry, CV) of the monomer in acidic solutions. Limited investigations were performed by cyclic voltammetry and quartz crystal microbalance (QCM). CV showed that phenazine units are present along the polymer chains and exhibit their peculiar electrochemistry. QCM measurements confirmed the deposition of a film on the electrode surface during cyclic voltammetry on 2,3-diaminophenazine (DAPh) solutions. Film structures were thoroughly investigated by X-ray photoelectron spectroscopy (XPS) analysis both through curve fitting of C1s and N1s signals. XPS was also performed following chemical derivatization of samples for NH2, C O, COOH and OH groups with fluorinated markers. As a result, the presence of NH2 groups could be excluded, COOH and C O groups were found to be minor defects, whereas OH groups, more abundant, were assigned partly to oximic groups (–C N–OH). The possible presence of other structural defects involving nitrogen (N–N and N+–O−groups) was also suggested by XPS. Finally, theoretical calculations on electron spin densities of 2,3-diaminophenazine radicals seem to support a 1,2 coupling mechanism for 2,3-diaminophenazine electrochemical polymerization.

Biomass sugars are a versatile platform for the production of a number of biobased products. Microbial lipids, obtained by means of oleaginous microorganisms, represent one conversion option. Most of the lipids accumulated in oleaginous microorganisms, are triglycerides which can be used as raw material in various oils-based processes including, for instance, the production of biodiesel and bioplastics. Biomass sugars, obtained from residual straws or lignocellulosic crops such as Arundo donax, contain both C5 and C6 compounds that must be effectively converted to make the overall process sustainable. Among the oleaginous microorganisms, the yeast Cryptococcus curvatus has attracted much attention thanks to the capacity to use both C5 and C6 sugars. In the present study Cryptococcus curvatus was investigated for the production of lipids from lignocellulosic hydrolysates of steam pretreated Arundo donax. The fermentation set-up was first optimized by using synthetic media. In particular, a number of parameters were investigated: the carbohydrates composition and concentrations, the carbon/nitrogen ratio and the nutrients composition by using the response surface methodology (RSM) analysis. Finally, a fed-batch process was implemented for the fermentation of Arundo donax hydrolysates, yielding a total lipid content of 64% of the dry cell weight., Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 1335-1337