Development Of Biorefineries Research Articles

Practitioners’ Perceptions of Co-Product Allocation Methods in Biorefinery Development—A Case Study of the Austrian Pulp and Paper Industry

The utilization of coproducts is a strategy that can be applied to increase the economic and environmental performance of industrial processes and thus reach an objective targeted in several environmental policies. In multi-output production processes, allocation needs to be performed to assess the products’ environmental and economic performance. It is crucial to choose an adequate allocation method, because this choice has been shown to strongly influence overall outcomes. Consequently, rash choices can lead to poor decision-making. Various ways to apply and combine allocation methods can be found in the academic literature, but it is often difficult to find sufficient guidance on how to choose an allocation method for a specific context. This study explores practitioners’ perceptions of the cost and environmental impact allocation methods used in biorefinery development (lignin, fiber fines) by applying the analytic hierarchy process (AHP). Results indicate that professional background represents a major factor influencing individual preferences and, thus, the selection of specific allocation methods. Policy makers should be aware that practitioners with different professional backgrounds have varying preferences for different allocation methods and that this influences the overall assessments. These factors, in turn, affect the interpretation of results, further decision-making and, ultimately, the realization of environmentally sound and economically viable biorefinery projects. This issue deserves more attention in biorefineries, but also in other multi-output production processes. The findings indicate a need to consider multidisciplinary, diverse views and knowledge when conducting such assessments and to display the underlying approaches transparently.

Superheated Steam Torrefaction of Biomass Residues with Valorisation of Platform Chemicals Part—2: Economic Assessment and Commercialisation Opportunities

Up to now biorefinery concepts can hardly compete with the conventional production of fossil-based chemicals. On one hand, conventional chemical production has been optimised over many decades in terms of energy, yield and costs. Biorefineries, on the other hand, do not have the benefit of long-term experience and therefore have a huge potential for optimisation. This study deals with the economic evaluation of a newly developed biorefinery concept based on superheated steam (SHS) torrefaction of biomass residues with recovery of valuable platform chemicals. Two variants of the biorefinery were economically investigated. One variant supplies various platform chemicals and torrefied biomass. The second variant supplies thermal energy for external consumers in addition to platform chemicals. The results show that both variants can be operated profitably if the focus of the platform chemicals produced is on high quality and thus on the higher-priced segment. The economic analysis gives clear indications of the most important financial influencing parameters. The economic impact of integration into existing industrial structures is positive. With the analysis, a viable business model can be developed. Based on the results of the present study, an open-innovation platform is recommended for the further development and commercialisation of the novel biorefinery.

Multi-criteria research lines on livestock manure biorefinery development towards a circular economy: From the perspective of a life cycle assessment and business models strategies

Livestock manure (LSM) is a profitable waste if handled sensibly, but simultaneously it imposes several environmental and health impacts if managed improperly. Several approaches have been adopted globally to cartel the problem associated with LSM management and recovery of value-added products, still, technological innovation needs further upgradation in consideration with the environment, energy, and economy. This review delivered a vibrant portrait of manure management, which includes, bioenergy generation and resource recovery strategies, their current scenario, opportunities, challenges, and prospects for future researches along with global regulations and policies. Several bioenergy generation and nutrient recoveries technologies have been discussed in details, still, the major glitches allied with these technologies are its high establishment costs, operational costs, manure assortment, and digestate handling. This review also discussed the techno-economic assessment (TEA) and life cycle assessment (LCA) of LSM management operation in the context of their economical and environmental sustainability. Still, extensive researches needed to build an efficient manure management framework to advance the integrated bioenergy production, nutrients recycling, and digestate utilization with least environmental impacts and maximal economical gain, which has critically discussed in the current review.

Agricultural waste biorefinery development towards circular bioeconomy

The concept of biorefinery depends on the recuperation of higher-value chemicals with potential for a wide dissemination and an untapped marketability. To construct a clearer picture of rural waste treatment system, this work was conducted to critically review the foremost regularly utilized agricultural waste management technologies from their state of the art, challenges for setting up the biorefinery and system of circular economy with self-efficient business model. The drivers that can make the biorefinery concept appropriate to waste management and the conceivable outcomes for its improvement to full scale were examined. Technological, strategic and market imperatives influence the effective usage of these frameworks. This review discusses the state-of-the-art biorefinery opportunities beyond conventional strategies as an economically viable solution to overcome numerous current challenges such as waste minimization and the biosynthesis of different high-value bioproducts biorefinery strategies, integrated approach as well as economic and environmental impact were discussed.

Sustainable processes for treatment and management of seafood solid waste

Seafood processing is an important economical activity worldwide and is an integral part of the food chain system. However, their processing results in solid waste generation whose disposal and management is a serious concern. Proteins, amino acids, lipids with high amounts of polyunsaturated fatty acids (PUFA), carotenoids, and minerals are abundant in the discards, effluents, and by-catch of seafood processing waste. As a result, it causes nutritional loss and poses major environmental risks. To solve the issues, it is critical that the waste be exposed to secondary processing and valorization for recovery of value added products. Although chemical waste treatment technologies are available, the majority of these procedures have inherent flaws. Biological solutions, on the other hand, are safe, efficacious, and ecologically friendly while maintaining the intrinsic bioactivities after waste conversion. Microbial fermentation or the actions of exogenously introduced enzymes on waste components are used in most bioconversion processes. Algal biotechnology has recently developed unique technologies for biotransformation of nutrients, which may be employed as a feedstock for the recovery of important chemicals as well as biofuel. Bioconversion methods combined with a bio-refinery strategy offer the potential to enable environmentally-friendly and cost-effective seafood waste management. The refinement of these wastes through sustainable bioprocessing interventions can give rise to various circular bioeconomies within the seafood processing sector. Moreover, a techno-economic perspective on the developed solid waste processing lines and its subsequent environmental impact could facilitate commercialization. This review aims to provide a comprehensive view and critical analysis of the recent updates in seafood waste processing in terms of bioconversion processes and byproduct development. Various case studies on circular bioeconomy formulated on seafood processing waste along with techno-economic feasibility for the possible development of sustainable seafood biorefineries have also been discussed.

Ethanol production from Agave tequilana leaves powder by Saccharomyces cerevisiae yeast applying enzymatic saccharification without detoxification

The replacement of fossil resources with renewable biomass in a bioeconomy is seen as a major contribution to climate change mitigation. The transformation from a petrochemical-based economy to a bio-based economy necessitates the novel exploitation of cost-effective natural materials for both future biorefinery development and a range of value-added products of interest. The present investigation proposes the use of Agave tequilana Weber leaves, an agro-industrial residue with a huge potential to produce liquid biofuels. The objective of the present work is to evaluate the alcoholic fermentation by S. cerevisiae yeast in powdered A. tequilana leaves (dry-mill,100 °C, diameter ≤ 300 µm) pretreated with two enzymatic saccharification processes without detoxification and determine the highest yield bioconversion of sugars to ethanol. Alcoholic fermentation was evaluated using yeast at different times (0−42) h with an initial concentration of 34.06 ± 0.4 g/L reducing sugars. S. cerevisiae has the highest ethanol production 12.20 ± 0.3 g/L within 18 h obtained an ethanol yield of 0.41 g/g (81% of theoretical value), and volumetric ethanol productivity 0.68 ± 0.02 g/L/h. Yeast was able to consume the 86.4% reducing sugars and increase to 17.2-fold cell concentration in the presence of 80.30 ± 0.70 mg/L phenolic compounds. This biotransformation of waste has great potential and significant prospects for wider industrial and biotechnological applications, the results show the feasibility and efficiency to produce ethanol, is a clean source of energy and offers a solution for countries that produce agave or similar feedstocks. It is firmly believed by the author that, due to the large amounts of waste produced by the tequila industry, the best solution for this problem does not lie in this paper or implementation of a single treatment. On the contrary, a mix of some of the alternative treatments presented in other works would probably represent the most efficient option, from both an economic and environmental point of view.

Trends in harnessing energy from waste biomass: pathways & future potential

Demand for fuel energy is continually on the rise. There is also a constant challenge involved to ensure that all our energy needs are fulfilled. Persistent overconsumption of conventional fossil fuels due to the rise in global population aided by economic expansion has resulted in reduction of fossil fuel reserves. This has fuelled the need to boost research efforts on renewable and sustainable bioenergy feedstocks. Since bioenergy utilizes organic matter; therefore, it is an economically viable and clean solution, which can minimize our reliance on non-renewable resources. The bioprocessing of lignocellulosic biomass to produce bio-based products under biorefinery setup is gaining global attention. The main challenge however remains to strike a balance between energy harvesting and economic viability with minimum environmental impacts. The development of zero-waste lignocellulosic biorefinery aligns completely with the idea of sustainable development without increasing carbon footprint. This concept is self-sustainable. It also advocates re-usage or recycling of waste; of which using lignocellulosic biomass waste is a major thrust. Improving the techno-economic efficiency of currently employed pretreatment methods and looking for combined pretreatment strategies will prove to be a stepping stone in the commercialization of zero-waste lignocellulosic biorefineries. This review investigates the most widespread pretreatment types, highlighs their advantages/disadvantages, and reviews the current status and technological advances in the bioconversion process of LCB into bioenergy in a biorefinery set-up.

Omega-3-fatty acids from algae for health benefits

Algal biotechnology grew progressively into a widespread industry with escalating statistics of entrepreneurial inventions endeavoring the utilization of its biochemical assortment for a broad range of applications in the recent past. They find their application in various industries such as the pharma and nutraceutical industries that use high-value biologically active ingredients such as omega-3 fatty acids, carotenoids, and other significant products. The algal growth metabolism is attractive to the eyes of researchers because of their potential to undergo photosynthesis alike the plants and unlike other microorganisms. They have a high adaptive capability, which helps them endure extreme environments such as temperature, salinity, pH, and photoperiod. Since they are photosynthetic organisms, they can harness their energy easily from CO2 and sunlight. In a biorefinery concept, omega-3 fatty acids extracted from microalgae are extensively applied in the field of nutrition and thus paving the way for the development of a cost-effective microalgal bio-refinery. Furthermore, the production of a high-value product, such as omega-3 from microalgae, will help promote the establishment of the microalgal industry for entrepreneurs. This article reviews the importance of omega 3 fatty acids, challenges in microalgal ω-3 fatty acids extraction, Lipid extraction methods used and their significance, and more feasible, yet, lucrative techniques for extraction in the current scenario.

One-pot conversion of engineered poplar into biochemicals and biofuels using biocompatible deep eutectic solvents

Integrating plant cell wall engineering and process consolidation using biocompatible deep eutectic solvents could enable the development of sustainable biorefineries that effectively utilize both carbohydrates and lignin.

Assessment of the Economic and Energetic Potential of Residues from the Green Coconut Industry

This work uses new waste feedstock, essential to increase the range of new biomasses, demonstrating experimentally and numerically the economic potential of coconut husk residues to produce renewable biofuels (pyrolytic oil and biochar) through slow pyrolysis. The samples were submitted to a pyrolysis process (500 ºC for 30 min, with a heating rate of 20 ºC min-1, using water vapor as carrier gas), where the biochar and bio-oil yields reached were 31 and 30%, respectively. The main components found in bio-oil were furfural (29.23%), phenol (22.18%), and isoeugenol (10.26%). The surface area values (Brunauer-Emmett-Teller (BET) and Langmuir) found for biochar were greater than 300 m2 g-1 and a micropore volume of 0.11 cm3 g-1. The estimated theoretical energy potential of biochar and bio-oil were 208,107,180 MJ and 190,205,438 MJ, equivalent to 3,729,518.4 tons of coconut husks. Thus, this study brings as a novelty a new feedstock associated with bioprocess technological models that will pave sustainable avenues for the development of biorefineries, offering a sustainable green option to produce bioproducts and bioenergy. In the proposed model, the wastes are valorized using various processes addressing economy.

Development of Biorefineries in the Bioeconomy: A Fuzzy-Set Qualitative Comparative Analysis among European Countries

This study aims to identify the configurational conditions that characterize the establishment of biorefineries in 20 European countries. After determining the conditions which support a bioeconomy transition, secondary data from national sources are used to represent their existing conditions within respective countries. Then, a fuzzy-set qualitative comparative analysis is employed to compare and contrast the effect of varying combinations of the selected conditions on the development of biorefineries. The conditions chosen include coherent bioeconomy strategies, network intensity of regional bioclusters, intellectual capital, and natural resource availability. Our results reveal that the configuration of a coherent bioeconomy strategy, sizable public spending on R&D, abundant biomass supply, and a high level of network intensity is sufficient to explain the pronounced biorefineries development among some European countries. We recommend that countries with fragmented approaches review and redesign the policy and regulatory framework to create a holistic and consistent bioeconomy strategy, taking into account the configurations of conditions as an important prerequisite. In particular, factors such as the lack of best practice examples, the low level of public spending on research and development, the economic capacities for a skilled workforce in addition to the sustainable supply of raw materials should be addressed as focal points.

Recent Advances in the Valorization of Lignin: A Key Focus on Pretreatment, Characterization, and Catalytic Depolymerization Strategies for Future Biorefineries

AbstractLignin is the largest renewable source of aromatics with an annual production of ≈50 to 70 million tons worldwide. Unfortunately, despite being a rich source of aromatic chemicals, almost 98% to 99% of lignin is burned as a low‐value fuel and only 1% to 2% is utilized as high‐value chemicals. It is noteworthy that lignin is cross‐linked with carbohydrate fractions of lignocellulosic biomass (LCB) through a stable lignin‐carbohydrate covalent complex, making it the main hurdle in converting LCB. Moreover, the stability of the inter‐unit linkages (COC, CC) and the strong interactions among the aromatic units, makes the separation into aromatic monomers challenging. Hence, a delignification pathway through a sustainable approach represents a formidable challenge for the development of future biorefineries. A breakthrough in several technological pathways, e.g., LCB fractionation, lignin characterization/depolymerization, and economic analysis are being considered. However, there remains a dearth of in‐depth understanding and a thorough know‐how. This review navigates readers through the latest cutting‐edge innovations in these four interconnected biorefinery aspects, and may inspire others to propagate the growth of biorefineries in the upcoming years. Overall, the objective of this review is to provide insights into lignin valorization technologies which may guide the future research toward sustainable biorefineries.

Insights into alkaline choline chloride-based deep eutectic solvents pretreatment for Populus deltoides: Lignin structural features and modification mechanism

Deep eutectic solvent (DES) is a kind of green solvent for biorefinery, which favors the progress of being more environmentally friendly and effective. A better understanding of structural changes of lignin is necessary to optimize pretreatment conditions and efficient utilization of the resultant lignin. The current study reported the structural features of lignin recovered from alkaline ChCl/imidazole and ChCl/urea DES pretreatment, and the mechanism of lignin modification was revealed. The profiling demonstrated that lignin samples possessed a high purity (>94.4%), low molecular weight ranging from 1544 to 2562 g/mol and an excellent uniformity (PDI < 1.6). Noteworthy, the content of β-O-4′ linkages in lignin was over 75% (i.e. 72.2%–77.4% retention); S/G ratio was increased whereas the content of -OCH3 groups were decreased. It was revealed that slight cleavage of β-O-4′ linkages, preferential breakdown of G units, and demethylation reaction were occurred during alkaline ChCl-based DES pretreatment. Specifically, cleavage of ester linkages between PB and lignin macromolecule was taking place during ChCl/imidazole pretreatment at a high temperature; whereas oxidation only appeared in ChCl/urea system. Despite the modification, well β-O-4′ preserved and less condensed lignin samples were recovered after low-temperature pretreatment. Consequently, high contents of phenol derivatives (26.3–30.6%) were achieved in lignin oil. The present study provides critical information on alkaline ChCl-based DES pretreatment, which will contribute to the valorization of lignin by-products and will be beneficial to the development of biorefineries.

Techno-economic risk assessment, life cycle analysis and life cycle costing for poly(butylene succinate) and poly(lactic acid) production using renewable resources

The sustainable production of poly(lactic acid) (PLA) or poly(butylene succinate) (PBS) from corn glucose syrup, corn stover and sugar beet pulp (SBP) have been assessed via process design, preliminary techno-economic evaluation, life cycle assessment and life cycle costing (LCC). Cost-competitive PLA and PBS production can be achieved in a SBP-based biorefinery, including separation of crude pectin-rich extract as co-product, leading to minimum selling prices of $1.14/kgPLA and $1.37/kgPBS. Acidification Potential, Eutrophication Potential and Human Toxicity Potential are lower when SBP is used. The LCC of PLA ($1.42/kgPLA) and PBS ($1.72/kgPBS) production from SBP are lower than biaxial oriented polypropylene (BOPP, $1.66/kg) and general purpose polystyrene (GPPS, $2.04/kg) at pectin-rich extract market prices of $3/kg and $4/kg, respectively. Techno-economic risk assessment via Monte-Carlo simulations showed that PLA and PBS could be produced from SBP at the market prices of BOPP ($1.4/kg) and GPPS ($1.72/kg) with 100% probability to achieve a positive Net Present Value at pectin-rich extract market prices of $3/kg and $4/kg, respectively. This study demonstrated that SBP-based biorefinery development ensures sustainable production of PLA and PBS as compared to fossil-derived counterparts and single product bioprocesses using glucose syrup and corn stover.

Integrated biorefinery development using winery waste streams for the production of bacterial cellulose, succinic acid and value-added fractions

An integrated biorefinery has been developed using winery wastes (grape pomace-GP, stalks-GS, wine lees-WL). Bacterial cellulose was produced from GP extracted free sugars. Grape-seed oil and polyphenols were extracted from GP. Experimental design was employed to optimize lignin removal (50.8%) from mixtures of remaining GP solids and GS via NaOH (1.19% w/v) treatment at 70°C for 30 min. Delignification liquid contained condensed tannins with 76% Stiasny number. Enzymatic hydrolysis produced a sugar-rich hydrolysate (40.2 g/L sugars). Ethanol, antioxidants, tartaric acid and nutrient-rich hydrolysate were produced from WL. The crude hydrolysates were used in fed-batch Actinobacillus succinogenes cultures for 37.2 g/L succinic acid production. The biorefinery produces 42.65 g bacterial cellulose, 24.3 g oil, 40.3 g phenolic-rich extract with 1.41 Antioxidant Activity Index, 80.2 g ethanol, 624.8 g crude tannin extract, 20.03 g tartaric acid and 157.8 g succinic acid from 1 kg of each waste stream.

Efficient Conversion of Glycerol to Ethanol by an Engineered Saccharomyces cerevisiae Strain.

Glycerol is an eco-friendly solvent that enhances plant biomass decomposition via glycerolysis in many pretreatment methods. Nonetheless, inefficient conversion of glycerol to ethanol by natural Saccharomyces cerevisiae limits its use in these processes. In this study, we have developed an efficient glycerol-converting yeast strain by genetically modifying the oxidation of cytosolic NAD (NADH) by an O2-dependent dynamic shuttle and abolishing both glycerol phosphorylation and biosynthesis in S. cerevisiae strain D452-2, as well as by vigorous expression of whole genes in the dihydroxyacetone (DHA) pathway (Candida utilis glycerol facilitator, Ogataea polymorpha glycerol dehydrogenase, endogenous dihydroxyacetone kinase, and triosephosphate isomerase). The engineered strain showed conversion efficiencies (CE) up to 0.49 g ethanol/g glycerol (98% of theoretical CE), with a production rate of >1 g liter-1 h-1 when glycerol was supplemented in a single fed-batch fermentation in a rich medium. Furthermore, the engineered strain converted a mixture of glycerol and glucose into bioethanol (>86 g/liter) with 92.8% CE. To the best of our knowledge, this is the highest reported titer of bioethanol produced from glycerol and glucose. Notably, we developed a glycerol-utilizing transformant from a parent strain which cannot utilize glycerol as a sole carbon source. The developed strain converted glycerol to ethanol with a productivity of 0.44 g liter-1 h-1 on minimal medium under semiaerobic conditions. Our findings will promote the utilization of glycerol in eco-friendly biorefineries and integrate bioethanol and plant oil industries. IMPORTANCE With the development of efficient lignocellulosic biorefineries, glycerol has attracted attention as an eco-friendly biomass-derived solvent that can enhance the dissociation of lignin and cell wall polysaccharides during the pretreatment process. Coconversion of glycerol with the sugars released from biomass after glycerolysis increases the resources for ethanol production and lowers the burden of component separation. However, low conversion efficiency from glycerol and sugars limits the industrial application of this process. Therefore, the generation of an efficient glycerol-fermenting yeast will promote the applicability of integrated biorefineries. Hence, metabolic flux control in yeast grown on glycerol will lead to the generation of cell factories that produce chemicals, which will boost biodiesel and bioethanol industries. Additionally, the use of glycerol-fermenting yeast will reduce global warming and generation of agricultural waste, leading to the establishment of a sustainable society.

Microalgae biomass as a sustainable source for biofuel, biochemical and biobased value-added products: An integrated biorefinery concept

Microalgal biomass has been proved to be a sustainable source for biofuels including bio-oil, biodiesel, bioethanol, biomethane, etc. One of the collateral benefits of integrating the use of microalgal technologies in the industry is microalgae’s ability to capture carbon dioxide during the application and biomass production process and consequently reducing carbon dioxide emissions. Although microalgae are a feasible source of biofuel, industrial microalgae applications face energy and cost challenges. To overcome these challenges, researchers have been interested in applying the bio-refinery approach to extract the important components encapsulated in microalgae. This review discusses the key steps of microalgae-based biorefinery including cultivation and harvesting, cell disruption, biofuel and value-added compound extraction along with the detailed technologies associated with each step of biorefinery. This review found that suitable microalgae species are selected based on their carbohydrate, lipid and protein contents and selecting the suitable species are crucial for high-quality biofuel and value-added products production. Microalgae species contain carbohydrates, proteins and lipids in the range of 8% to 69.7%, 5% to 74% and 7% to 65% respectively which proved their ability to be used as a source of value-added commodities in multiple industries including agriculture, animal husbandry, medicine, culinary, and cosmetics. This review suggests that lipid and value-added products from microalgae can be made more economically viable by integrating upstream and downstream processes. Therefore, a systematically integrated genome sequencing and process-scale engineering approach forimproving the extraction of lipids and co-products iscritical in the development of futuremicroalgal biorefineries.

Sustainability index accounting food and carbon benefits on circular 2,3-butanediol biorefinery with oil palm empty fruit bunches

Progressive replacement of petroleum chemicals with biomass derived products is an essential research goal toward sustainability. However, the progress of the development of new generation biorefinery has been affected by many factors, i.e., prices of crude oil, food, and carbon. To quantify the environmental and social impacts of the technologies, this study constructed a sustainability index for calculating two new bio-butanediol production processes with oil palm empty fruit bunches as example feedstock. The performance of organosolv pretreatment using butanediol was compared with the whole slurry conversion process using sulfite pretreated biomass, over the petroleum refinery and first generation biorefinery with food crop feedstock. The organosolv biorefinery process successfully converted the biomass into 77.3 ± 1.63 g/L of bio-butanediol (0.45 g/g yield), which is slightly higher (5.5%) than that of the sulfite-based process. The integration of biorefinery techniques, with oil palm farming shall result in 6.8 kg-CO2 and 0.5 kg-food benefits per kg butanediol produced, yielding a sustainability index of 7.30. The food index for first generation biorefinery is −1.04 kg food per kg butanediol produced. Using empty fruit bunches for butanediol production could save 1.54 kg food crop consumption, which turns the “food vs. fuel competition” into a “food plus fuel nexus”.

Sphingobacterium prati sp. nov., isolated from agricultural soil and involved in lignocellulose deconstruction.

A bacterial strain, arapr2T, was isolated from agricultural soil sampled in Reims, France. Based on its 16S rRNA gene sequence, the strain was affiliated to the family Sphingobacteriaceae and more specifically to the genus Sphingobacterium . The strain had 98.31 % 16S rRNA gene sequence similarity to its closest relative Sphingobacterium canadense CR11T and 98.25 % to Sphingobacterium pakistanensis NCCP-246T. Genome relatedness indexes revealed that the average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between arapr2T and its closest relative ( S. canadense CR11T) were 92.97 % and 52.00 %, respectively; for S. pakistanensis NCCP-246T, the ANI and dDDH values were 82.46 and 27.6%, respectively. The genomic DNA of strain arapr2T was 6.02 Mbp long, had a DNA G+C content of 40.4 mol% and had 5504 protein-coding genes. The results obtained in this study suggests that strain arapr2T (CIP 111872T=LMG 31848T) represents a new species for which the name Sphingobacterium prati sp. nov. is proposed. Due to the fact that this strain has been isolated using wheat straw as carbon source, this novel bacterial strain represents a promising biotechnological tool for the fractionation of lignocellulosic biomass in the context of biorefinery development.

Synergistic effects of hydrothermal and deep eutectic solvent pretreatment on co-production of xylo-oligosaccharides and enzymatic hydrolysis of poplar

Full utilization of lignocellulose is critical for its biorefinery development. In this study, a sustainable biorefinery process based upon poplar sawdust was established using sequential hydrothermal and deep eutectic solvent treatment (HP-DES). Results showed that single hydrothermal pretreatment (HP) could produce 53.2% xylo-oligosaccharides (XOS) (based on raw xylan), while the enzymatic digestibility was low. Conversely, single DES treatment achieved effective enzymatic digestibility but low XOS yields. As compared to HP, both DES treatment and HP-DES showed high selectivity for lignin removal and high glucose yield. Surprisingly, most of HP-DES residues had obviously lower enzymatic digestibilities than those of single DES residues. This was mainly explained by the differences of the surface lignin contents between DES and HP-DES residues. Moreover, nearly complete enzymatic hydrolysis of HP-DES residues was achieved with the addition of bovine serum albumin. This work demonstrated this HP-DES yielded XOS, fermentable sugar, and pure lignin with high processibility.