Pretreatment Of Pulp Research Articles

Fungi as biotechnological allies: Exploring contributions of edible and medicinal mushrooms.

Edible and medicinal mushrooms possess excellent nutritional properties due to their incredible versatility in growing on different substrates and producing extracellular enzymes with a wide range of specificity. These features make them excellent candidates for various biotechnological applications. In this context, biotechnological applications using edible and medicinal mushrooms can focus on the bioprocessing of agro-industrial wastes, an economical and environmentally friendly strategy. This review, based on recent original research and scientific reviews, highlights the versatility and potential of mushrooms in terms of sustainability and efficiency. We emphasized the biotechnological applications of edible and medicinal mushrooms and their enzymes including food production with high nutraceutical value by enhancing the quality and flavor of food industry products. Other biotechnological applications addressed in this review were cosmeceutical and biomedical development using mushroom extracts with bioactive compounds; wood pulp pretreatment processes in the pulp and paper industry; bioethanol production; and bioremediation for decontaminating soils and polluted effluents. These applications explain how edible and medicinal mushrooms have gained significance in biotechnology over the years, opening new avenues for innovation. The current tendency to study edible and medicinal mushrooms has gained the attention of researchers because these are still less known organisms becoming an attractive and natural source of novel bioactive compounds that could be integrated into a circular model production.

Effect of treating birch kraft pulp with peracetic acid before O2-delignification on the properties of pulp and consumption of ClO2 in D0ED1 bleaching

The influence of pre-treating Kappa number of 18.0 industrial birch kraft pulp with peracetic acid (Paa) before oxygen delignification (OD) was studied relative to the pulps’ level of delignification, yield, brightness, intrinsic viscosity (IV), FS-number, tear index (TI), and the consumption of chlorine dioxide (ClO2) in its subsequent Elemental Chlorine Free (ECF) bleaching. The study showed that such pretreatment is a way to extend the delignification of such pulp quite selectively in OD based on values of IV, FS-number, and TI, and to reduce significantly the consumption of ClO2 required to bleach this pulp to a brightness of 87%. This reduction depended on the amount of Paa used for pulp pretreatment. For example, when 0.33% and 0.66% as active oxygen (A.O.) of Paa were used, ClO2 consumption to bleach the pulp to 87% was lowered by 15.4% and 42.3%, respectively. As high as a 61.5% reduction in ClO2 consumption in its bleaching could be obtained using 0.66% as A.O. on pulp and change of time of OD. This result allows for a significant decrease in the chlorine passing to the filtrates from washing the pulp after the D0 and E stages to the pulp mill wastewater treatment plant.

Reactivity assessment of oligomeric systems associated with crystalline and amorphous cellulose for bioethanol production: a DFT study.

The production of bioethanol from renewable raw materials is a decisive factor in the economic development of many countries. However, the complexity of the processes and the numerous experimental variables involved require a deeper understanding of the chemical reactions that take place during bioethanol production to define optimal parameters. Here, we have employed density functional theory-based calculations to investigate the local reactivity of oligomeric systems by consideringcrystalline and amorphous cellulose models to better understand some details regarding pulp pretreatment processes. Our results evidence a higher chemical susceptibility of amorphous portions of cellulose to chemicals typically employed in acid hydrolysis. Additionally, we observed that glucose monomers coming from cellulose hydrolysis may undergo oxidation, leading to the formation of byproducts such as hydroxymethylfurfural (HMF), acetic acid, formic acid, and levulinic acid. The analysis of local chemical softness indexes indicated that cellulose hydrolysis may be associated with intermediate chemical steps. Finally, we investigated the influence of distinct solvents (dielectric constants) on the local reactivity of the systems, evidencing a relevant role of the solvent dielectric constant for cellulose degradation in glucose. Initial three-dimensional structures were constructed. Pre-optimizations were performed in a Hartree-Fock (HF) approach employing thePM7 semi-empirical hamiltonian. The structures were then re-optimized via density functional theory (DFT). The local reactivity study of the systems was conducted through the condensed-to-atoms Fukui indexes (CAFI). Systematic changes of the dielectric constants were also considered in geometry optimization and CAFI calculations to estimate the influence of solvents on the reactivity of the systems.

Effects of Sugar Beet Pulp Pretreatment Methods on Hydrogen Production by Dark Fermentation

Methane and hydrogen generated from waste and biomass are renewable resources, which may successfully replace traditional fossil fuels. This paper investigates the enhancement effect of lignocellulosic biomass pretreatment on dark fermentative hydrogen production from sugar beet pulp (SBP). The results showed that sugar beet pulp after pretreatment contained significant amounts of unfermented sugars (mainly glucose, arabinose, galactose, and raffinose), and, therefore, represented an attractive substrate for methane and hydrogen production. The greatest methane yield (495 dm3 CH4/kg VS) was achieved from sugar beet pulp after alkaline pretreatment. High methane production of up to 445 dm3 CH4/kg VS was also obtained using acidic and enzymatic hydrolysis as a preliminary treatment of the pulp. All the pretreatment methods also resulted in the enhancement of hydrogen yield with the highest value of 229 dm3 H2/kg VS achieved using acid hydrolysis compared with 17 dm3 H2/kg VS for raw material subjected to digestion.

The Effect of Mechanical Pre-treatment of Reject Pulp as Raw Material for LOCC Mixture on Medium Paper Quality

Reject pulp is pulp that is stuck in the screen hole during the pulp screening process because it is larger than the screen hole and has shives (more than two fiber chains that are still bonded), as well as blackish brown knots. Reject pulp from the process will be stored in landfills resulting in accumulation which can pollute the environment if the amount continues to increase in line with the production being carried out. Therefore, innovation is needed so that rejected pulp can be reprocessed. The current problem in the industry is reject pulp which has the effect of decreasing the value of paper properties and causing the surface of the paper to become rough. In this study, pre-treatment will be given for screen and material blending during beating. This study aims to determine the potential of reject pulp to be used as a mixture of LOCC raw materials on medium paper and the most optimum mechanical treatment to produce the best quality medium paper. The results in this study obtained the optimum value for the pre-treatment screen beating itself, namely a bursting factor of 27.70 g.m2/g.cm2, a tensile index value of 39.18 N.m/g, and a smoothness value of 9.425 Sec/10 ml. Meanwhile, the ring crush value obtained was the optimum value for the pre-treatment screen beating mix, which was 11.25 N.m/g. These results have met the standard properties of medium paper.

Enhancing the efficiency and functionality of xylanase from Bacillus sp. RTS11: Optimization, purification, characterization, and prospects in kraft pulp bleaching.

Bacillus sp. RTS11, a xylanolytic strain, was isolated from the Algerian desert rocks. Genetic analysis revealed a remarkable 98.69% similarity to Bacillus pumilus. We harnessed optimization techniques, including Plackett-Burman screening and Box-Behnken optimization design, to amplify xylanase production and activity. The outcome of these efforts was an optimized medium that yielded an impressive xylanase production titer of 448.89 U, a threefold increase compared to the non-optimized medium (146 U). The Purification of xylanase was achieved through the three-phase partitioning technique, employing t-butanol and various chromatographic methods. Notably, anion exchange chromatography led to isolating a highly pure enzyme with a molecular weight of 60 kDa. The xylanase exhibited its peak activity at a temperature of 60°C and a pH of 9.0. When applied to pulp pretreatment, 20 U/g of xylanase demonstrated a substantial increase in the release of phenolic and chromophore compounds while reducing sugar content in the pulp. Furthermore, this versatile xylanase shows its ability to efficiently hydrolyze a variety of agro-industrial residues, including wheat bran, corn and grape waste, wheat straw, and sugarcane bagasse. These findings underscore the significant potential of this xylanase enzyme in biobleaching processes and the utilization of agro-industrial waste, opening up exciting avenues for sustainable and environmentally friendly industrial applications.

The Influence of Pre-Treatment of Grape, Cherry, and Strawberry Pulp with Enzyme Preparations of Pectinase and Cellulase on some Organic Compounds Amount in their Extracts

The Influence of Pre-Treatment of Grape, Cherry, and Strawberry Pulp with Enzyme Preparations of Pectinase and Cellulase on some Organic Compounds Amount in their Extracts

Construction and Characterization of Fitting Equations for a New Wheat Straw Pulping Method.

The pretreatment of pulp with enzymes has been extensively studied in the laboratory. However, due to cost constraints, the application of enzymes in the pulp and paper industry is very limited. In this paper, an environment-friendly and efficient pulping method is proposed as an alternative to traditional pulping and papermaking methods. This new method overcomes the low efficiency and extreme pollution problems associated with traditional pulping methods. In addition, fitting equations for the new pulping method are constructed using data on enzyme treatments, which reflect the effect of enzymes and enable the realization of real-time control of the pulping process. The experimental results show that the efficiency of the pulping and papermaking process can be improved using biological enzymes, and the separation of cellulose can be facilitated using mixed enzymes, which have a better effect than single enzymes.

Disposable bamboo fiber meal boxes characterized by efficient preparation, excellent performance, and the potential for beneficial degradation

Disposable plastic meal boxes account for a significant proportion of global plastic pollution, which has caused an increasingly urgent need for substitution with biodegradable plant fiber-molded meal boxes. Compared to other chemical-mechanical pulp pre-treatment methods, steam explosion is a more efficient and clean approach for the preparation of molded meal boxes. In this study, disposable bamboo fiber meal boxes made from steam-exploded pulp (SEP) were prepared using steam explosion. The results showed that the meal boxes prepared using this method had a compact interweaving structure, good tensile performance (with a tensile modulus 1.9 times higher than that of meal boxes prepared using chemical-mechanical pulp (CMP)), excellent water resistance (with a permeability 0.58 times lower than that of CMP), high compression strength, and excellent toughness. After being discarded, SEP was found to have no adverse effects on the soil pH or electrical conductivity (EC) during the degradation process. Furthermore, it could increase the levels of major nutrients for plant growth, such as N and P, improve the C/N ratio, enhance microbial activity, and improve soil fertility. Moreover, the CO2 release rate during the entire degradation process was found to be low. Thus, the bamboo fiber meal boxes developed in this study can alleviate the environmental pressure caused by the greenhouse effect, thereby achieving a green life cycle of highly efficient preparation, stable use, and beneficial degradation.

Hemicellulose-rich paper-grade pulp as raw material for regenerated fibres in an ionic liquid-based process

Hemicellulose-rich pulp raw materials are avoided in the production of man-made cellulosic textile fibres due to hemicellulose reactivity with the currently used industrial solvent systems. Incorporation of hemicelluloses in regenerated fibres could, however, increase the share of used wood biomass and thus improve the environmental footprint of regenerated fibre products. Superbase ionic liquids have shown potential in dissolving and regenerating all the major wood polymers i.e. cellulose, hemicellulose and lignin into regenerated products. In this work, regenerated fibres were spun from hemicellulose-rich softwood and eucalyptus paper-grade pulps and eucalyptus dissolving pulp using a superbase ionic liquid [mTBNH][OAc]. Before dissolution and spinning, intrinsic viscosities of the paper-grade pulps were adjusted either enzymatically or by using a mild acid-treatment to improve dope rheology for dry-jet wet spinning. In fibre spinning, hemicellulose was found to regenerate in high yield and the obtained regenerated fibres had high dry tenacities (5.3 to 15 cN/dtex). The best mechanical properties were measured from fibres with high hemicellulose content (17.3% (w/w)). Pulp pretreatment was found to be critical for achieving good mechanical properties. Acid-pretreatment, which modified both cellulose and hemicellulose, yielded regenerated fibres with better mechanical properties compared to an enzyme-pretreatment which did not alter the hemicellulose structure. Removal of hemicellulose substituents and hydrolysis of hemicellulose backbone in acid-pretreatment may be the key to improved mechanical properties in hemicellulose-containing regenerated fibres. Enzymatic peeling and imaging with a xylan-specific monoclonal antibody (CCRC-M138) suggest that hemicelluloses were enriched to the outermost layers of the regenerated fibres.

Effects of various acid catalysts in dimethyl isosorbide/water co-solvent system for lignocellulosic biomass pretreatment

Novel organosolv pretreatments of biomass using biobased green solvents have attracted increasing attention to realize sustainable biorefinery. We have demonstrated that the feasibility of dimethyl isosorbide/water co-solvent in fractionating lignocellulosic biomass (Eucalyptus) for multiple products under a mild condition (120 °C, 60 min). To take a further step towards revealing the effects of catalysts, we explored various Brønsted (e.g., H2SO4, HCl, and p-TsOH), Lewis acid catalysts (e.g., AlCl3 and FeCl3) and their combinations in this co-solvent system. An interesting finding was that the delignification efficiency of AlCl3 was lower than that of H2SO4 (69.9% vs 91.2%), while the cellulose conversion efficiency of the pretreated pulp was similar (∼80%). It is hypothesized that the presence of Al3+ could inhibit the binding of lignin to cellulase, which was supported by the quantum chemistry calculations. Results revealed the presence of cation− π interactions between Al3+ and lignin with interaction energy (ΔE) was 1022.04 kJ/mol and 1003.04 kJ/mol for S and G type of lignin, respectively. In addition, the pretreatment with H2SO4 -AlCl3 co-catalyst could achieve a high lignin removal efficiency of 93.0% and almost complete enzymatic hydrolysis of obtained cellulose pulp (∼100%). This research demonstrated that the co-catalyst strategy effectively improved the overall performance of the solvent-based biorefinery.

Enhanced energy savings in enzymatic refining of hardwood and softwood pulp

BackgroundPulp refining is an energy consuming, but integral part of paper production with the aim to increase tensile strength and smoothness of paper sheets. Commercial enzyme formulations are used to lower the energy requirements by pre-treatment of pulp before refining. However, a high number of different commercial enzyme products are available on the market containing enzymes of varying origin and composition, which complicates the prediction of their behavior, especially using different pulp types.ResultsEndoglucanase-rich enzyme formulations were characterized regarding enzyme activity at different temperatures, resulting in a significant decrease of activity above 70 °C. Some enzyme preparations additionally contained arabinosidase, xylanase and β-glucosidase activity consequently resulting in a release of xylose and glucose from pulp as determined by high-performance liquid chromatography. Interestingly, one enzyme formulation even showed lytic polysaccharide monooxygenase (LPMO) activity of 3.05 nkat mg−1. A correlation between enzyme activity using the endoglucanase specific derivatized cellopentaose (CellG5) substrate and enzyme performance in laboratory PFI (Papirindustriens forskningsinstitut) refining trials was observed on softwood pulp resulting in a maximum increase in the degree of refining values from 27.7°SR to 32.7°SR. When added to a purified endoglucanase enzyme (31.6°SR), synergistic effects were found for cellobiohydrolase II (34.7°SR) or β-glucosidase enzymes (35.7°SR) in laboratory refining. Comparison with previously obtained laboratory refining results on hardwood pulp allowed differences in enzyme performance based on varying pulp types to be elucidated.ConclusionsInterestingly, the individual enzymes indeed showed different refining effects on softwood and hardwood pulp. This difference could be predicted after development of an adapted enzyme activity assay by combination of the derivatized cellopentaose CellG5 substrate with either softwood or hardwood sulfate pulp.

Coffee pulp pretreatment methods: A comparative analysis of hydrolysis efficiency

The Vietnamese food industry produces a lot of coffee pulp, which is a valuable and abundant source of agricultural by-products. It contains a lot of cellulose, which can be converted into bioethanol. However, coffee pulp needs an extensive pretreatment to reduce the amount of lignin and hemicellulose while retaining the initial cellulose composition. This study compared several pre-hydrolysis and pre-fermentation pretreatment methods which involved H2SO4, NaOH, microwaves, and white rot fungus Phanerochaete chrysosporium.
 The hemicellulose dropped by 43.8% after the acidic pretreatment, by 47.1% after the alkaline pretreatment, and by 12.8% after the microbial pretreatment. The lignin contents dropped by 4.2, 76.6, and 50.2% after acidic, alkaline, and microbial pretreatment, respectively. The removal of hemicellulose and lignin in the coffee pulp was much more efficient when two or three of the pretreatment methods were combined. The microwave-assisted acid and alkaline pretreatment was the most efficient method: it removed 71.3% of hemicellulose and 79.2% of lignin. The combined method also had the highest amount of reducing sugars and glucose in hydrolysate. Additionally, concentrations of such yeast inhibitors as 5-hydroxymethyl-2-furaldehyde (HMF) and furfural were 2.11 and 3.37 g/L, respectively.
 The acid pretreatment was effective only in removing hemicellulose while the alkaline pretreatment was effective in lignin removal; the fungal pretreatment had low results for both hemicellulose and lignin removals. Therefore, the combined pretreatment method was found optimal for coffee pulp.

Efficiency of Chemical Pretreatment of Sugar Beet Pulp Biomass Intended to Energy Production via Biological Processes

Environmentally friendly anaerobic digestion (AD) of lignocellulose-based materials is becoming an increasingly popular alternative to non-renewable energy sources. It also corresponds with the principles of sustainable development. The structure of lignocellulosic materials, which is resistant to biodegradation, requires using pretreatment methods prior to subjecting them to anaerobic processes. The aim of the study was to evaluate the influence of temperature and type of hydrolyzing agent on the efficiency of chemical pretreatment of sugar beet pulp. Biomass samples soaked in distilled water and 0.05 M solutions of NaOH and H2SO4 were left for 20 h, both at room temperature (22 °C) and in a thermostated chamber (50 °C). The changes in pH, electrolytic conductivity (EC), concentration of volatile fatty acids (VFA), dissolved chemical oxygen demand (COD), and phenols were analyzed. The concentration of CODdissolved, demonstrating the efficiency of pretreatment methods, obtained after alkaline hydrolysis conducted at 22 °C was almost at the same level as in the case of acid hydrolysis carried out at 50 °C: 3451 mg dm−3 and 3608.5 mg dm−3, respectively. Hydrolysis carried out in a NaOH solution at 22 °C appears to be the most economical option for sugar beet pulp pretreatment out of all analyzed ones, as there is no need to increase expenditure on heating samples.

Techno-economic analysis of the production of 2G ethanol and technical lignin via a protic ionic liquid pretreatment of sugarcane bagasse

The increasing demand for renewable energy, fuels, and chemicals encourages the development of new biorefinery processes. This work presents a techno-economic analysis of the pretreatment of sugarcane bagasse using the protic ionic liquid 2-hydroxyethylammonium acetate ([MEA][OAc]) considering four washing methods to remove it from the pretreated pulp. In the best scenario, the increased enzymatic hydrolysis yield and the more efficient counter-current washing method contributed to an increased ethanol yield of 33 %. Despite the lower increment in ethanol yield compared with other second-generation processes, the production of technical lignin increased the reaction mass efficiency of the biorefinery by 5.6 % and led to an internal rate of return two percentage points higher. However, wastewater and vinasse production increased by 26 % and 50 %, respectively. These results indicate that protic ionic liquids are potentially good pretreatment agents to produce fuels and chemicals from biomass, thus underpinning the establishment of new biorefinery processes. • Process development to produce ethanol and technical lignin from bagasse. • Different washing steps yielded different hydrolysis and fermentation yields. • Techno-economic analysis indicates the importance of using protic ionic liquids. • Protic ionic liquid pretreatment has better economic results because of lignin. • Recycling of ionic liquid plays an important role in process economic feasibility.

Enrichment of Residual Carbon in Coal Gasification Fine Slag via Wet Sieving Separation with Ultrasonic Pretreatment.

To overcome the environmental and economic challenges posed by the increasing amounts of the coal gasification slag, here, a simple and efficient method for enriching the residual carbon from the coal gasification fine slag was proposed. The residual carbon enrichment pattern in the particle size distribution of coal gasification fine slags after the ultrasonic pretreatment was mainly enriched toward the 500-250 μm and 250-125 μm particle size classes by analyzing the changes in the particle size distribution and apparent morphology. The pulp pretreatment at the ultrasonic output power of 270 W for 4 min was determined as the optimal experimental condition with respect to the yield, ash content, and ash rejection of the concentrates. Compared to the conventional wet sieving separation, the yield and ash content of the final concentrates were reduced by 7.99 and 14.96%, respectively. Moreover, the ash rejection of the final concentrates was as high as 88.51%, indicating an increment of 11.63% than the conventional wet sieving separation. Furthermore, thermogravimetric analysis confirmed that the final concentrates exhibited the lowest reactivity; however, these demonstrated had the highest carbon content (nearly 70%) with 27.27% ash content. The combustion characteristics analysis showed that the wet screening concentrate after ultrasonic pretreatment had the highest composite combustion characteristic index (S) of 3.17 × 10-8, as compared to the raw and conventional sieving concentrates.

Fabrication of cellulose cryogel beads via room temperature dissolution in onium hydroxides

In recent years, there has been a growing interest in green solvents to dissolve and shape cellulose into microspheres. However, development of solvents suitable for room temperature dissolution and shaping of cellulose spheres is very limited. In this work, a novel process to fabricate cellulose microspheres is presented. First, the effect of ethanol-hydrochloric acid pulp pretreatment on cellulose solubility in aqueous tetra-n‑butyl phosphonium hydroxide and tetra-n‑butyl ammonium was investigated. While the dissolution of untreated pulp remained limited to 5 wt%, the pretreatment boosted pulp solubility to 15 wt%. Spherical beads were obtained via dropwise addition of the solution in ethanol. Cryogels beads with a BET surface area of 218.1 m²/g were collected when using 90 v% tert‑butyl alcohol as the freeze-drying medium. After gathering the spent ethanol and initial washing of the beads, 90.7% of the tetra-n‑butyl phosphonium hydroxide solution was recovered and successfully reused to prepare a subsequent batch of beads. The proposed bead preparation system further fits within the concept of topochemical design as beads could be fabricated from low to high cellulose concentrations, regardless of temperature, therefore offering great opportunities to design gels for different applications such as drug delivery systems, protein conjugation or wastewater treatment.

Feasibility of substituting old corrugated carton pulp with thermal alkali and enzyme pretreated semichemical mechanical rice straw pulp

In this study, we separately used a laboratory Hollander beater, a pilot scale 12″ single-disc refiner and an expanded trial with a commercial paper mold mill to investigate the feasibility of using thermal-alkali/enzyme pretreated rice straw semi-chemical mechanical pulp to substitute portions of old corrugated carton board (OCC) pulp in the paper industry. In the laboratory plan, sequential treatments of NaOH at a 5–10% dosage and enzymes at a 0.2–4% dosage were applied to rice straw, followed by beating using a Hollander beater for 1–2 h to complete the rice straw semi-chemical mechanical pulping process. When the NaOH dosage, enzyme dosage and refining time were 10%, 0.2% and 1 h, the best quality rice straw pulp was obtained. Along with the increase in NaOH dosage, the pulp freeness decreased significantly, and the pulp accepted rate increased. Enzymatic treatment enhanced rice straw quality only after NaOH dosage treatment, which then reacted with rice straw to increase the quality of pulp. In the expanded trial, the rice straw semi-chemical mechanical pulp was blended with OCC pulp (0%, 25%, 50%, 75% and 100%) to form handsheets. Along with an increase in rice straw proportions, the tensile index, burst index, and ring-crush index increased by 109–200%, 13–196%, and 124–187%, respectively. In an online commercial paper mold mill trial, blending rice straw pulp with OCC could successfully make paper-mold egg cartons, with both mill operation and product smoothness appearance being highly acceptable.

Electrocoagulation pretreatment of pulp and paper wastewater for low pressure reverse osmosis membrane fouling control.

Low pressure reverse osmosis (LPRO) has been increasingly used in advanced treatment of pulp and paper wastewater (PPWW) for the purpose of water reuse. However, membrane fouling is a major problem encountered by full-scale RO systems due to the organic and inorganic contents of the feedwater. Electrocoagulation (EC) as an effective treatment for foulants removal can be applied in pre-filtration. Therefore, the LPRO membrane fouling mechanism and the membrane fouling control performance by EC treatment were investigated in this study. EC pretreatment could reduce the membrane fouling and improve the membrane flux by 31%, by effectively removing and/or decomposing the organic pollutants in PPWW. Fluorescent spectrometry analyses of the feedwater and the permeate revealed that humic acid-like and fulvic acid-like organics in PPWW were the major foulants for the LPRO membranes. Fourier transformation infrared spectrometry results confirmed that the organic foulants contained benzoic rings and carboxylic groups, which were typical for organic substances. EC effectively removed organic pollutants containing functional groups such as carboxylic acid COH out-of-plane bending, olefin (trans), and NH3+ symmetrical angle-changing. Moreover, the extended Derjaguin-Landau-Verwey-Overbeek model suggested that the membrane filtered 30-min EC-treated PPWW had the strong repulsion force to foulants due to the higher cohesion energy (12.1mJ/m2) and the lower critical load, which theoretically explained the reason of EC pretreatment on membrane fouling control.

Ozone pretreatment facilitating cellulase hydrolysis of unbleached bamboo pulp for improved fiber flexibility

In this study, an integrated and feasible approach by combining ozone pretreatment and cellulase hydrolysis of unbleached bamboo kraft pulp (UBKP) to improve the fiber flexibility was proposed. Ozone was utilized as green facilitator of cellulase treatment for increased enzyme accessibility and improved fiber flexibility by removing lignin and particle carbohydrates. Ozone was found to decrease the fiber stiffness and reduce the lignin content of UBKP fibers from 14.46 wt% to 9.96 wt%. The DP of UBKP was also decreased to 1210 after ozone-cellulase treatment, with a reduced carboxyl content of 0.064 mmol/g. The flexibility of UBKP fibers treated by ozone-cellulase system was 34.68 × 1014/(N·m2), which was 7 times higher than that of the original UBKP fibers. This study put forward a practical and sustainable approach to improve the flexibility of UBKP fibers, and to further study the possibility of ozone oxidation chemistry in cellulase hydrolysis process, thus would further broaden the high-value application of UBKP and ozone technology in tissue paper production.