Pretreated Oil Palm Empty Fruit Bunch Research Articles

Integrated Biorefinery Approach: The Generation of Bioproducts Vanillin and Biomethane Through a Sequential Bioconversion of Lignocellulose From Oil Palm Empty Fruit Bunch (OPEFB)

AbstractThe efficient utilization of all of the key lignocellulosic biomass residues is important for the development of an integrated biorefineries uassing this as its feedstock. In this study, a process involving a simultaneous pre-treatement process with anaerobic digestion (AD) were implemented for processing oil palm empty fruit bunches (OPEFB) in order to produced both vanillin and methane. Before and after treatment with the dry rot fungus (Serpula lacrymans) the biomass was analyzed for total reducing sugar (TRS), total soluble phenols (TSP), pH, and weighed. Change in the physical characteristic and morphology of untreated and OPEFB following fungal culture was observed using scanning electron microscopy (SEM). The biomethane potential (BMP) of pretreated OPEFB significantly increased (62.07%) compared to untreated sample and in addition. The amount of vanillin extracted reached 3.48ug mL−1. This study therefore confirms that multiple products can effectively be isolated using a fungal preatreatment of lignocellulosic OPEFB followed by anerobic fermentation of biomass residual thus maximizing the potential returns and reducing environmentally impacts compared to other pretreatments.

Effects of pretreatments on the chemical composition and thermal conversion of oil palm empty fruit bunch

The combustion of oil palm empty fruit bunch (OPEFB) can cause severe fouling, slagging, and ash melt-down problems, which originate from its non-organic components such as potassium, calcium, and silicon. To improve the usability of OPEFB as raw materials for combustion energy generation, the effects of pretreatments with various solution on the chemical composition and the thermal degradation were investigated. Soaking pretreatments with alkali, acidic, and neutral conditions were applied. The acid soaking pretreatments resulted in the reduction of the alkaline ash materials, although the silicon and the chlorine were effectively reduced by the alkali or the water soaking pretreatment. The changes in the ash composition by the different pretreatment conditions resulted in the changes of thermal properties. The pretreated OPEFB showed increased thermal degradation temperatures, indicating the improvement of the thermal stability by the pretreatment. The results of the various pretreatments showed that the water soaking pretreatment of OPEFB could be a promising pretreatment method to improve the applicability for combustion as a bio-fuel, in terms of economic viability and environmental sustainability.

Large scale production of succinic acid by fermentation of sequential inorganic salt pretreated oil palm empty fruit bunch

The abundance of accumulated oil palm wastes has led to their usage as substrate in the production of organic acid such as succinic acid (SA). For the first time, oil palm empty fruit bunch (OPEFB) which was pretreated using inorganic salts was utilized for SA production in a large-scale fermenter. OPEFB was pretreated sequentially using 15% (w/v) Na3PO4.12H2O and 5% (w/v) ZnCl2 solution before undergoing fermentation process in a 16 L bioreactor in the presence of Actinobacillus succinogenes ATCC 55618. The optimum fermentation conditions were adopted from small-scale setting and implemented in the large-scale setting. Two different fermentation approaches were studied; simultaneous saccharification and fermentation (SSF) and modified simultaneous saccharification and fermentation (mSSF). This research revealed that mSSF produced higher concentration of total reducing sugars (TRS) yield and SA compared to the SSF method. SSF of inorganic salts pretreated OPEFB produced maximum SA concentration (38.85 gL-1) and yield (0.39 gg-1). Meanwhile highest TRS yield obtained from pre-hydrolysis was 0.79 gg-1 at 72 h and SA (50.5 gL-1) was acquired under the mSSF at 132 h. Therefore, mSSF is a novel process that has propitious potential for SA production in a large-scale setting which can be further executed in the industrial scale.

Pengaruh penambahan surfaktan pada fermentasi tandan kosong kelapa sawit dengan praperlakuan uap air panas bertekanan dengan katalis asam maleat

Oil palm empty fruit bunch (OPEFB) has high potency to be converted into second generation bioethanol production. OPEFB pretreated liquid hot water (LHW) assisted maleic acid (MA) pretreatment was used as substrate in simultaneous saccharification fermentation (SSF). This pretreatment was conducted at 180 °C for 70 min by using 1.5% (w/v) MA acid concentration with material and liquid ratio of 1:14. Subsequently, the pretreated samples were fermented by addition of surfactant, polyethylene glycol (PEG) 4000 and amphiphilic lignin derivatives (A-LD) using Kluyveromyces marxianus InaCC Y119 yeast at temperature of 38 °C for 89 h. Before SSF, pretreated OPEFB was pre hydrolyzed by cellulase enzyme with enzyme loading 30 FPU/g at 50 °C for 3 h. Fermentation filtrate was taken at 0, 24, 48, 72, dan 89 h as much as 1.5 mL for reducing sugar and ethanol content determination. The surfactant addition can enhance reducing sugar and also ethanol content compared to control. The highest ethanol content of 1.251 g/L was found at fermentation of OPEFB pretreated MA with PEG 4000 surfactant at 89 h.

Naganishia cerealis IN1S2.5 oil production from the hydrolysate of NaOH-impregnated and catalyst steam explosion pretreated oil palm empty fruit bunch

NaOH-impregnation with catalyst steam explosion was found to be an efficient pretreatment method for oil palm empty fruit bunch (OPEFB) as a substrate for oil production by Naganishia cerealis IN1S2.5. Cellulase hydrolysis of the pretreated OPEFB yielded glucose at 0.364 g/g. Investigation of N. cerealis IN1S2.5 oil production in the OPEFB hydrolysate revealed a maximum oil yield (2.46 g/L) when the C/P molar ratio of the OPEFB hydrolysate was adjusted to 25.71, supplemented with Ca2+ and Zn2+, and set to pH 4. The N. cerealis IN1S2.5 oil was comprised of oleic (37.6%), palmitic (36.2%), and steric (17.9%) acids, all (w/w), as the major fatty acids. Predicted properties of the produced biodiesel indicated the potential of N. cerealis IN1S2.5 oil as a biodiesel feedstock.

Ionic solution pretreatment of oil palm empty fruit bunch to produce sugars

Ferric (III) chloride, when prepared as an ionic solution, was used to pretreat oil palm empty fruit bunch (OPEFB) before undergoing enzymatic hydrolysis to convert into value-added products. The pretreatment was assisted with microwave irradiation to improve the degradation of recalcitrant structure of lignocellulosic materials with minimum time. The effects of salt concentration, temperature, and duration of pretreatment on the chemical composition of OPEFB and total reducing sugar (TRS) yield were investigated. The results revealed that the best pretreatment occurred at pretreatment time of 10 min, 100 °C, and ferric chloride concentration of 10 w/v%. The TRS yield achieved using the pretreated OPEFB was approximately 0.485 g/g, which was three times higher than the non-pretreated OPEFB, which was only 0.154 g/g. Thus, the ionic solution pretreatment method is a promising alternative for replacing other pretreatment methods.

Combination of ultrasonication and deep eutectic solvent in pretreatment of lignocellulosic biomass for enhanced enzymatic saccharification

The synergistic effect of ultrasonication with deep eutectic solvent (DES) on pretreatment of oil palm empty fruit bunch (OPEFB) was investigated. Three different types of DESs, namely choline chloride:lactic acid (ChCl:LA), choline chloride:urea (ChCl:U) and choline chloride:glycerol (ChCl:G) were applied. The performance of the pretreatment was evaluated based on yield of reducing sugars, lignin content, crystallinity index, structural and morphology changes. ChCl:LA pretreated OPEFB attained the highest yield of reducing sugars (36.7%) under the action of ultrasonication for 15 min at sonication power 60% (210 W) and temperature 50 °C, followed by ChCl:U (35.8%) and ChCl:G (35.3%). Under these conditions, ChCl:LA pretreated OPEFB showed significant change in structural and morphology, associated with the lowest crystallinity and lignin content. ChCl:LA promoted the pretreatment process in view of its intrinsic properties of low viscosity and low surface tension. The incorporation of ultrasonication in DES pretreatment significantly increased the reducing sugars yield suggested the synergistic effect of ultrasonication with DES pretreatment. These signifies that ultrasound-assisted DES pretreatment could be a promising alternative pretreatment technique for lignocellulosic biomass.

Pretreatment of Oil Palm Empty Fruit Bunch (OPEFB) at Bench-Scale High Temperature-Pressure Steam Reactor for Enhancement of Enzymatic Saccharification

Up scaling of biomass pretreatment from laboratory scale to a bench-scale reactor is one of important steps in the application of the pretreatment for pilot or commercial scale. This study reports the optimization of pretreatment conditions, namely reaction temperature and time, by one factor at a time (OFAT) method for the enhancement of enzymatic saccharification of oil palm empty fruit bunch (OPEFB). OPEFB was pretreated using high temperature-pressure steam reactor with different reaction temperatures (160, 170, 180, 190, 200 °C) and times (10, 20, 30, 40, 50 min). The effectiveness of the pretreatment was determined based on chemical compositions of untreated and pretreated OPEFB and sugar production from enzymatic saccharification of the pretreated OPEFB. Solubilized components in the water that generates the steam were also determined. Pretreatment at 180°C for 20 min provides the highest sugar yields (97.30% of glucose yield per initial cellulose and 88.86% of xylose yield per initial hemicellulose). At the optimum condition 34.9% of lignin and 30.75% of hemicellulose were successfully removed from the OPEFB and resulted in 3.43 delignification selectivity. The relationship between severity factor and by-products generated and the sugars obtained after enzymatic saccharification were discussed. The pretreated OPEFB at the optimum condition was also characterized for its morphological characteristic by scanning electron microscopy (SEM) and crystallinity by X-ray diffractometry (XRD) and then compared it with untreated one. The steam pretreatment caused some fiber disruptions with more defined and opened structures and increased of the crystallinity index (CrI) by 2.9% compared to the untreated OPEFB

Strategy to enhance the sugar production using recyclable inorganic salt for pre-treatment of oil palm empty fruit bunch (OPEFB)

Inorganic salts were used for the pretreatment of oil palm empty fruit bunches (OPEFB) to enhance the delignification and saccharification yield of OPEFB. The sequential pretreatment of OPEFB using sodium phosphate dodecahydrate (Na3PO4.12H2O) and zinc chloride (ZnCl2) proved to be an effective approach. OPEFB was delignified by 58.8%, producing a maximum total reducing sugar (TRS) yield of 0.97 g/g under optimum pretreatment conditions of 15% Na3PO4.12H2O, 60 min (30 min/stage) pretreatment time, 10% solid to liquid ratio, and pretreatment temperature of 121 °C. In addition, structural and morphological analysis of the pretreated OPEFB using field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectroscopy, and X- ray diffraction (X-RD) revealed major structural changes, such as the generation of porous structure, which allows for better enzyme accessibility. Moreover, recycle experiments showed encouraging findings, as the spent pretreatment liquid with pH adjustment can be recycled efficiently for at least 5 times without a substantial decrease in its effectiveness.

Delignification of oil palm empty fruit bunch via ultrasound-assisted deep eutectic solvent pretreatment

Lignin is the complex organic polymers contain in lignocellulosic biomass, acting as structural support of the biomass. Its presence making the biomass recalcitrance to bioprocessing. Therefore, pretreatment is essential in removing the lignin content to enhance the sugar extraction and bioethanol production from lignocellulosic biomass. In this work, pretreatment of oil palm empty fruit bunch (OPEFB) using ultrasound-assisted deep eutectic solvents (DESs) was performed. Three types of DESs, namely choline chloride-lactic acid (ChCl-LA), choline chloride-glycerol (ChCl-G) and choline chloride-urea (ChCl-U) in delignification were studied. The pretreatment was conducted with the presence of ultrasonication. The DESs recyclability were also performed in this work. ChCl-LA exhibited the best delignification properties, in which ChCl-LA pretreated OPEFB had the lowest total lignin content of 18.8%, followed by ChCl-U (19.4%) and ChCl-G (21.2%). All the three DESs were successfully recycled with slight decrement in delignification performance after two recycles. The recyclability of the DESs would improve the economic feasibility of the pretreatment process.

Chemical-free pretreatment of unwashed oil palm empty fruit bunch by using locally isolated fungus (Schizophyllum commune ENN1) for delignification

Biological pretreatment of unwashed oil palm empty fruit bunch (OPEFB) by Schizopyllum commune ENN1 was carried out to obtain optimum conditions of delignification. Locally isolated fungus, S. commune ENN1, was grown on oily OPEFB and the biomass was simultaneously delignified. Hence, the incubation time (7d–28d), temperature (25°C–40°C), and amount of substrate (3g–9g) were investigated to improve the efficiency of lignin removal during the biological pretreatment. Maximum lignin peroxidase and manganese peroxidase were produced at each optimal parameter, and correlated with maximum lignin removal. A similar pattern of maximum cellulase was produced by S. commune ENN1 at optimal parameters with only minimal activity of around 5U/g (CMCase). A maximum lignin removal of 67.9% was achieved at optimum condition at a temperature of 30°C by using 5g of OPEFB after 14d of incubation time. The cellulose content was increased by 31.7% of the biologically pretreated OPEFB at optimum condition. These findings showed that S. commune ENN1 was feasible to remove the lignin and increase the cellulose content of unwashed OPEFB through biological pretreatment for enzymatic hydrolysis.

Microwave assisted aqueous ammonia pretreatment of oil palm empty fruit bunch: effect on lignin removal and morphological structure

Oil palm empty fruit bunch (OPEFB) is an abundant solid waste produced by oil palm industries to which the cellulose, hemicellulose, and lignin content has potential for conversion into high value biochemical products. However, pretreatment must be applied to remove lignin thus making cellulose and hemicellulose available for further conversion. In this study, effect of three parameters of microwave assisted aqueous ammonia pretreatment such as microwave power (280; 560; 840 Watt), NH3 concentration (7.5; 10; 12.5 % w/v), and reaction time (3; 6; 9 minutes) on lignin removal (%) were evaluated by using response surface methodology with Box-Behnken design. OPEFB at different size ranging from 30 – 40 mesh was used as the raw material. Moreover, to evaluate the morphological structure, scanning electron microscope (SEM) analysis was employed both on untreated and pretreated OPEFB. The quadratic model showed that microwave power of 837.8 Watt, NH3 concentration of 12.2% (w/v), and reaction time of 8.9 minutes resulted the highest lignin removal of 81.60%. SEM images showed that pretreated OPEFB encountered a heavy structural destruction. These results show that microwave assisted aqueous ammonia pretreatment can be a promising method to be applied to disrupt the compact lignocellulose structure of OPEFB and to remove its lignin content efficiently under very short period of time.

Effect of combined pretreatment of lignocellulose and the kinetics of its subsequent bioconversion by Aspergillus niger

Abstract Lignocellulose is the most abundant material to be a renewable raw material for bioethanol production. However, the high percentage of lignin content makes it resistant to be hydrolyzed thus inhibits the production of reduced sugar. This problem is overcome by performing a proper pretreatment prior to hydrolysis. This study examined the feasibility oil palm empty fruit bunch (OPEFB) as the source of lignocellulose and Aspergillus niger as cellulase-producing fungus respectively. The hydrolysis was performed by growing A. niger on the OPEFB. Prior to hydrolysis, OPEFB was pretreated with NaOH at different percentage and were heated simultaneously at 170 °C to destroy lignin that hindered cellulase from contacting cellulose. A. niger was further grown on pretreated OPEFB and the reducing sugar was determined via dinitrosalicylic acid method with spectrophotometer reading at 540 nm periodically every 24 h for 9 consecutive days. Kinetics study showed that the yield of the reducing sugar is relatively higher for OPEFB pretreated with 1% NaOH due to the reduction of the cellulose crystallinity which further increase the hydrolysis rate.

Optimization of Microwave-Assisted Oxalic Acid Pretreatment of Oil Palm Empty Fruit Bunch for Production of Fermentable Sugars

Pretreatment is an important step in the conversion of biomass to bioethanol. In this study microwave-assisted oxalic acid (MOA) pretreatment was chosen to pretreat oil palm empty fruit bunch (OPEFB) to enhance enzymatic saccharification of the biomass. The objective of this study was to determine an optimum pretreatment condition for reducing sugar production, which could be further fermented by yeast to produce ethanol. Preliminary study was conducted to determine the range of duration of heating and temperature that will be used in the optimization by using response surface methodology (RSM). Central composite design (CCD) was used with three independent variables (duration of heating, temperature and acid concentration). Reducing sugar yield per initial biomass was used as a response variable. Preliminary study, that was conducted at 160, 170, 180, 190, and 200 °C for 5, 7.5, 10, 12.5, and 15 min, shows that pretreatment at temperature of 170–190 °C for 5–10 min produced higher reducing sugars than other conditions. Optimization using RSM shows that the optimum condition of MOA pretreatment of OPEFB was at 190 °C for 3 min with 1.1% oxalic acid, which resulted in as much as 34.60% reducing sugars after enzymatic saccharification. The pretreated OPEFB was then characterized and compared with untreated OPEFB. MOA pretreatment successfully removed 50.57% of lignin and 76.56% of hemicellulose from the OPEFB that were confirmed by a decrease or disappearance of the absorption bands of functional groups at 1339–1650 cm−1 and 1735 cm−1, respectively.

The Improvement of Sugar and Bioethanol Production of Oil Palm Empty Fruit Bunches (Elaeis guineensis Jacq) through Microwave-Assisted Maleic Acid Pretreatment

Microwave assisted maleic acid (MA) pretreatment is a potential method for biomass processing. The aim of the present study was to determine the optimum conditions for pretreatment of oil palm empty fruit bunch (OPEFB) for bioethanol production, as well as to understand the changes of functional groups in the pretreated OPEFB. The optimum pretreatment conditions with the highest reducing sugar yield (RSY) (47.21%) were 190 °C for 2.5 min with 1% MA. The temperature had more influence on the chemical components and RSY than the other pretreatment parameters. More severe pretreatment conditions tended to dissolve more sugar into the hydrolysates. Structural changes occurred in the OPEFB pretreated with MA and sulfuric acid, which were observed by the absence of certain functional groups. The simultaneous saccharification and fermentation (SSF) of MA-pretreated OPEFB produced ethanol with a concentration of 18.9 g/L and yield of 0.43 g ethanol/g cellulose after pretreatment, or equivalent to 76.6% of theoretical maximum yield. Microwave assisted MA pretreatment of OPEFB successfully increased the RSY about 300% compared to the untreated one. The MA pretreatment removed hemicellulose and lignin. The highest ethanol concentration and yield were produced after 48 h of SSF of the OPEFB pretreated with MA.

Combination of Superheated Steam with Laccase Pretreatment Together with Size Reduction to Enhance Enzymatic Hydrolysis of Oil Palm Biomass.

The combination of superheated steam (SHS) with ligninolytic enzyme laccase pretreatment together with size reduction was conducted in order to enhance the enzymatic hydrolysis of oil palm biomass into glucose. The oil palm empty fruit bunch (OPEFB) and oil palm mesocarp fiber (OPMF) were pretreated with SHS and ground using a hammer mill to sizes of 2, 1, 0.5 and 0.25 mm before pretreatment using laccase to remove lignin. This study showed that reduction of size from raw to 0.25 mm plays important role in lignin degradation by laccase that removed 38.7% and 39.6% of the lignin from OPEFB and OPMF, respectively. The subsequent saccharification process of these pretreated OPEFB and OPMF generates glucose yields of 71.5% and 63.0%, which represent a 4.6 and 4.8-fold increase, respectively, as compared to untreated samples. This study showed that the combination of SHS with laccase pretreatment together with size reduction could enhance the glucose yield.

Effects of Surfactant on the Enzymatic Degradation of Oil Palm Empty Fruit Bunch (OPEFB)

Various pretreatments have been employed to pretreat oil palm empty fruit bunch (OPEFB) to improve sugars production via enzymatic degradation reaction. However, less attention has been paid to investigate the effects of surfactant addition in the OPEFB degradation process. Therefore, the effects of surfactants on degradation of pretreated OPEFB by Aspergillus niger EFB1 crude cellulase were studied. Tween 80 was the most effective surfactant tested. When 0.25% (v/v) Tween 80 was added, the production of reducing sugar increased 63% (from 0.49 to 0.8 g/L). This was the optimum yield recorded. It also improved cellobiose, glucose and xylose production by two folds, seven folds and one fold higher than that without Tween 80, respectively. Tween 80 reduced the loss of cellulases activities where more than 17% of the original cellulases activities were retained after 7 days of degradation. Nonetheless, Tween 80 did not improve the protein concentration consistently. Supplementation of Tween 80 increased lignin removal by 23%. Observations using SEM revealed that, with Tween 80, the presence of pores and surface cracks were more pronounced on the surface of degraded OPEFB fibers. As a whole, the reported effects showed an improved production of reducing sugars in the presence of Tween 80. Thus, Tween 80 addition appeared as a promising method in enhancing the bioconversion of OPEFB into value-added co-products.

Sodium Hydroxide-Steam Explosion Treated Oil Palm Empty Fruit Bunch: Ethanol Production and Co-Fermentation with Cane Molasses

Oil palm empty fruit bunch (OPEFB) was pretreated by NaOH-steam explosion and then fermented to ethanol by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes using Kluyveromyces marxianus G2-16-1 at 40 oC. The maximum ethanol production by the SHF and SSF processes was 8.09 g/L (22.21 g/L reducing sugar, 0.08 g/g OPEFB) and 13.658 g/L (0.136 g/g OPEFB), respectively, at 48 h. The OPEFB hydrolysate mixed with molasses to 22% (w/v, total sugar) gave an ethanol yield of 61.60 g/L (0.38 g/g total sugar) at 72 h, while molasses alone gave 53.89 g/L (0.34 g/g total sugar). The OPEFB slurry (OPEFBS; OPEFB hydrolysate containing the solid residue of pretreated OPEFB) gave a maximum ethanol yield of 68.77 g/L (0.44 g/g total sugar) when it was mixed with molasses. Scanning electron micrographs of the solid OPEFB residue in the OPEFBS showed yeast cells adsorbed to the OPEFB fibers. The results indicated that ethanol production from molasses mixed with OPEFB hydrolysate was equal to the cumulative sum of ethanol production from each raw material, and the solid OPEFB residue in the OPEFBS increased the ethanol production in the co-fermentation of molasses and OPEFB hydrolysate.

Effect of Buffering System on Acetone-Butanol-Ethanol Fermentation by Clostridium acetobutylicum ATCC 824 using Pretreated Oil Palm Empty Fruit Bunch

Change of pH has been identified as the most significant parameter in modulating the transition between the conversions of acids into solvents in acetone-butanol-ethanol (ABE) fermentation by Clostridia. Thus, ABE fermentation at various phosphate buffer concentrations and initial pH values was conducted using pure glucose and sugars derived from pretreated oil palm empty fruit bunch (OPEFB). A higher solvent concentration (2.93 g/L) was obtained in the fermentation using 20 g/L of glucose with buffer compared with one without buffer that produced 1.34 g/L of solvents. Approximately 8.77 and 9.15 g/L of solvents were produced from fermentation using 40 g/L of glucose with and without buffer, respectively. In the latter conditions, at an initial pH of 5.5, 8.77 g/L of solvents was obtained, which was the highest concentration compared to other initial pH values. Increasing the buffer concentration to 0.2 M at an initial pH of 6.0 resulted in acid accumulation of 16.83 g/L but reduced the solvent production to 1.36 g/L. In addition, ABE fermentation using 20 g/L of sugars from pretreated OPEFB produced 2.25 g/L of solvents with a yield of 0.13 g/g, which was comparable with fermentation using 20 g/L of glucose conducted in a buffering system.

Crude Cellulase from Oil Palm Empty Fruit Bunch by Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2 for Fermentable Sugars Production

Cellulase is an enzyme that converts the polymer structure of polysaccharides into fermentable sugars. The high market demand for this enzyme together with the variety of applications in the industry has brought the research on cellulase into focus. In this study, crude cellulase was produced from oil palm empty fruit bunch (OPEFB) pretreated with 2% NaOH with autoclave, which was composed of 59.7% cellulose, 21.6% hemicellulose, and 12.3% lignin using Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2. Approximately 0.8 U/ml of FPase, 24.7 U/ml of CMCase and 5.0 U/ml of β-glucosidase were produced by T. asperellum UPM1 at a temperature of 35 °C and at an initial pH of 7.0. A 1.7 U/ml of FPase, 24.2 U/ml of CMCase, and 1.1 U/ml of β-glucosidase were produced by A. fumigatus UPM2 at a temperature of 45 °C and at initial pH of 6.0. The crude cellulase was best produced at 1% of substrate concentration for both T. asperellum UPM1 and A. fumigatus UPM2. The hydrolysis percentage of pretreated OPEFB using 5% of crude cellulase concentration from T. asperellum UPM1 and A. fumigatus UPM2 were 3.33% and 19.11%, with the reducing sugars concentration of 1.47 and 8.63 g/l, respectively.