Ethanol production from enzymatic hydrolysis of sugarcane bagasse pretreated with lime and alkaline hydrogen peroxide

In this work we evaluated ethanol production from enzymatic hydrolysis of sugarcane bagasse. Two pretreatments agents, lime and alkaline hydrogen peroxide, were compared in their performance to improve the susceptibility of bagasse to enzymatic action. Mild conditions of temperature, pressure and absence of acids were chosen to diminish costs and to avoid sugars degradation and consequent inhibitors formation. The bagasse was used as it comes from the sugar/ethanol industries, without grinding or sieving, and hydrolysis was performed with low enzymes loading (3.50 FPU g⁻¹ dry pretreated biomass of cellulase and 1.00 CBU g⁻¹ dry pretreated biomass of ??-glucosidase). The pretreatment with alkaline hydrogen peroxide led to the higher glucose yield: 691 mg g⁻¹ of glucose for pretreated bagasse after hydrolysis of bagasse pretreated for 1 h at 25 °C with 7.35% (v/v) of peroxide. Fermentation of the hydrolyzates from the two pretreatments were carried out and compared with fermentation of a glucose solution. Ethanol yields from the hydrolyzates were similar to that obtained by fermentation of the glucose solution. Although the preliminary results obtained in this work are promising for both pretreatments considered, reflecting their potential for application, further studies, considering higher biomass concentrations and economic aspects should be performed before extending the conclusions to an industrial process.     

Pretreatment of sweet sorghum bagasse for hydrogen production by Caldicellulosiruptor saccharolyticus

Pretreatment of sweet sorghum bagasse, an energy crop residue, with NaOH for the production of fermentable substrates, was investigated. Optimal conditions for the alkaline pretreatment of sweet sorghum bagasse were realized at 10% NaOH (w/w dry matter). A delignification of 46% was then observed, and improved significantly the efficiency of enzymatic hydrolysis. Under hydrolysis conditions without pH control, up to 50% and 41% of the cellulose and hemicellulose contained in NaOH-pretreated sweet sorghum bagasse were converted by 24 h enzymatic hydrolysis to soluble monomeric sugars. The extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus showed normal growth on hydrolysates of NaOH-pretreated biomass up to a sugar concentration of 20 g/L. Besides hydrogen, the main metabolic products detected in the fermentations were acetic and lactic acid. The maximal hydrogen yield observed in batch experiments under controlled conditions was 2.6 mol/mol C6 sugar. The maximal volumetric hydrogen production rate ranged from 10.2 to 10.6 mmol/(L h). At higher substrate concentrations the production of lactic acid increased at the expense of hydrogen production.     

Pretreatment of cassava stems and peelings by thermohydrolysis to enhance hydrolysis yield of cellulose in bioethanol production process

The potential of wastes obtained from the cultivation of Manihot esculenta Crantz as raw material for bioethanol production was studied. The objective was to determine the optimal conditions of hemicellulose thermohydrolysis of cassava stems and peelings and evaluate their impact on the enzymatic hydrolysis yield of cellulose. An experimental design was conducted to model the influence of factors on the pentose, reducing sugar and phenolic compound contents. Residues obtained from the optimal pretreatment conditions were hydrolysed with cellulase (filter paper activity 40 FPU/g). The hydrolysates from pretreatment and enzymatic hydrolysis were fermented respectively using Rhyzopus spp. and Sacharomyces cerevisiae. The yield of enzymatic hydrolysis obtained under the optimal conditions were respectively 73.1% and 86.6% for stems and peelings resulting in an increase of 39.84% and 55.40% respectively as compared to the non-treated substrates. The ethanol concentrations obtained after fermentation of enzymatic hydrolysates were 1.3 and 1.2 g/L respectively for the stem and peeling hydrolysates. The pentose and phenolic compound concentrations obtained from the multi-response optimization were 10.2 g/L; 0.8 g/L and 10.1 g/L; 1.3 g/L respectively for stems and peelings. The hydrolysates of stems and peelings under these optimal conditions respectively gave ethanol concentrations of 5.27 g/100 g for cassava stems and 2.6 g/100 g for cassava peelings.     

Hydrogen production from water hyacinth through dark- and photo- fermentation

This article discusses the method of producing hydrogen from water hyacinth. Water hyacinth was pretreated with microwave heating and alkali to enhance the enzymatic hydrolysis and hydrogen production in a two-step process of dark- and photo- fermentation. Water hyacinth with various concentrations of 10–40 g/l was pretreated with four methods: (1) steam heating; (2) steam heating and microwave heating/alkali pretreatment; (3) steam heating and enzymatic hydrolysis; (4) steam heating, microwave heating/alkali pretreatment and enzymatic hydrolysis. Water hyacinth (20 g/l) pretreated with method 4 gave the maximum reducing sugar yield of 30.57 g/100 g TVS, which was 45.6% of the theoretical reducing sugar yield (67.0 g/100 g TVS). The pretreated water hyacinth was used to produce hydrogen by mixed H₂-producing bacteria in dark fermentation. The maximum hydrogen yield of 76.7 ml H₂/g TVS was obtained at 20 g/l of water hyacinth. The residual solutions from dark fermentation (mainly acetate and butyrate) were used to further produce hydrogen by immobilized Rhodopseudomonas palustris in photo fermentation. The maximum hydrogen yield of 522.6 ml H₂/g TVS was obtained at 10 g/l of water hyacinth. Through a combined process of dark- and photo- fermentation, the maximum hydrogen yield from water hyacinth was dramatically enhanced from 76.7 to 596.1 ml H₂/g TVS, which was 59.6% of the theoretical hydrogen yield.     

Comparative study on ethanol production from pretreated sugarcane bagasse using immobilized Saccharomyces cerevisiae on various matrices

Microwave alkali pretreated sugarcane bagasse was used as a substrate for production of cellulolytic enzymes, needed for biomass hydrolysis. The pretreated sugarcane bagasse was enzymatic hydrolyzed by crude unprocessed enzymes cellulase (Filter paper activity 9.4 FPU/g), endoglucanase (carboxymethylcellulase, 148 IU/g), β-glucosidase (116 IU/g) and xylanase (201 IU/g) produced by Aspergillus flavus using pretreated sugarcane bagasse as substrate under solid state fermentation. Concentrated enzymatic hydrolyzate was used for ethanol production using Saccharomyces cerevisiae immobilized on various matrices. The yield of ethanol was 0.44 g_p/g_s in case of yeast immobilized sugarcane bagasse, 0.38 g_p/g_s using Ca-alginate and 0.33 g_p/g_s using agar-agar as immobilization matrices. The immobilized yeast studied up to 10 cycles in case of immobilized sugarcane bagasse and up to 4 cycles in case of agar-agar and calcium alginate for ethanol production under repeated batch fermentation study.     

Production of polyhydroxybuyrate (PHB) from switchgrass pretreated with a radio frequency-assisted heating process

Effects of radio frequency (RF) heating as a biomass pretreatment process to generate hydrolysates for polyhydroxybuyrate (PHB) were evaluated in all production steps from pretreatment to enzymatic hydrolysis to fermentation. Switchgrass was pretreated under alkaline conditions with RF-assisted heating (traditional water bath (WB) heating as control) and subsequently enzymatically hydrolyzed. Fermentation was conducted with recombinant Escherichia coli strain for PHB production using the hydrolysates as carbon sources with or without yeast extract (YE) supplemented. Results indicated that the hydrolysates generated through RF pretreatment performed consistently better for PHB production than WB (50% higher PHB levels without YE). YE supplementation (up to 5 g/L) enhanced fermentation under all conditions and diminished the difference among performances of fermentations. When adding 2 g/L YE, PHB production increased by 200% and 80% for WB and RF hydrolysates, respectively. Supplementation of 5 g/L YE brought the final PHB concentration to be very close to each other for all three fermentation conditions. Compared to traditional heating process, the unique heating mechanism of RF generates harsher conditions (under regular pressure) to disrupt the biomass structure more completely and generate more nutrients for bacterial fermentation. RF was therefore proved to be an efficient process for biomass pretreatment.     

Pretreatment enhanced structural disruption,enzymatic hydrolysis,fermentative hydrogen production from rice straw

Rice straw (RS) is one of the major lignocellulosic wastes in the world and an abundant feedstock for producing biofuels and chemicals. However, RS is difficult to decompose. In this study, NaOH/urea and electrohydrolysis pretreated RS were used to enhance the structural disruption, enzymatic hydrolysis, and fermentative hydrogen production. Scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy analyses demonstrated that both NaOH/urea and electrohydrolysis pretreatments could effectively disrupt the lignin structure and increase the cellulose crystallinity of RS. Following pretreatment, RS was hydrolyzed by cellulase. After 96 h of enzymatic hydrolysis, NaOH/urea- and electrohydrolysis-pretreated RS produced 3.2- and 1.7-fold higher total reducing sugars than the unpretreated RS (232.95 ± 3.60 mg/g), respectively. Finally, the obtained RS hydrolysates were used for fermentative hydrogen production. NaOH/urea- and electrohydrolysis-pretreatment hydrolysates produced 125.0 and 163.0 mL H₂/g RS, respectively, which is much higher than the hydrogen yield of unpretreated hydrolysates.     

Preliminary evaluation of organosolv pre-treatment of sugar cane bagasse for glucose production: Application of 2 experimental design

Sugar cane bagasse was submitted to ethanol organosolv pre-treatment using a 50 L pilot scale reactor. The influence of catalyst type (H₂SO₄ or NaOH), catalyst concentration (1.25–1.50% w/w on dry fiber) and process time (60–90 min) on total solid recovery and solid composition (glucan, xylan and lignin contents) was evaluated by performing a 2³ full factorial experimental design. Pretreated sugar cane bagasse was further submitted to enzymatic hydrolysis using a commercial enzyme complex formed by cellulases and β-glucosidases. Glucose concentration in the hydrolysates and glucose yield referred to initial raw material (g glucose/100 g sugar cane bagasse) were used to select the best operational conditions. Concerning the enzymatic hydrolysis, the resulting glucose concentration was found to be dependent on xylan contents of the pretreated material. The modelling equations for glucose concentration and glucose yield as a function of the pre-treatment variables and the statistical analysis are also discussed in this work.     

Acetone-butanol-ethanol (ABE) fermentation using the root hydrolysate after extraction of forskolin from Coleus forskohlii

The biomass obtained after the extraction of forskolin from the roots of Coleus forskohlii was evaluated as a substrate for the production of acetone-butanol-ethanol (ABE). The spent biomass constituting more than 90% of the raw material showed 50–70% carbohydrates with starch and cellulose being the major constituents. This study was undertaken to optimize enzymatic hydrolysis of C. forskohlii roots for maximum release of fermentable sugars and subsequent fermentation to ABE. The root biomass was hydrolyzed using the Stargen® 002 and Accellerase® 1500. Cocktail of both enzymes (16U Stargen® 002 and 60 FPU Accellerase® 1500) could produce 41.2 g/l of total reducing sugars (glucose equivalent to 32.33 g/l). The production of ABE was optimized in a batch fermentation using Clostridium acetobutylicum NCIM 2877. The maximum ABE production using the root hydrolysates was 0.55 g/l. Pretreatment with lime and Amberlite XAD-4 increased the production of total solvent to 5.33 g/l.     

Evaluation of hydrogen production from corn cob with the mesophilic bacterium Clostridium hydrogeniproducens HR-1

Corn cob is a promising hydrogen fermentation substrate, not only because of its abundant and low cost, but also because of its high cellulose and hemicellulose content. However, little information is available on the use of corn cob as a feedstock for hydrogen production. In this study, corn cob was hydrolyzed by cellulase after acid steam-explosion, alkali soaking, or steam-explosion pretreatment. The liquid products of pretreatment and the enzymatic hydrolysates were then used as carbon sources for hydrogen production by Clostridium hydrogeniproducens HR-1. Pretreatment followed by enzymatic hydrolysis yielded 720, 670, and 530 mg reducing sugars/g corn cob, and the hydrogen yield from corn cob reached 119, 100, and 83 ml H₂/g corn cob, which is 55.9%, 46.7%, and 38.8% of the theoretical hydrogen yield from corn cob using C. hydrogeniproducens HR-1, respectively.     

Preliminary exploration on pretreatment with metal chlorides and enzymatic hydrolysis of bagasse

Converting biomass to fermentable sugar is the critical step in the biomass refinery. Moreover, pretreatment of biomass plays an important role in improving the conversion of biomass to sugar. In this study, sugarcane bagasse was pretreated by metal chloride Lewis acids (0.1 mol L⁻³ CrCl₃, FeCl₃, FeCl₂, ZnCl₂ and AlCl₃ solution) for cellulase hydrolysis. The effects of pretreatments on the yield, chemical components, and sequential cellulase hydrolysis of pretreated bagasse were investigated. The results indicated that metal chlorides with different pKa values could efficiently remove the hemicellulose in bagasse during pretreatment. Furthermore, an inhibition factor (IF) quantitatively reflecting difficulty of cellulase hydrolysis was proposed. The low IF means the facile cellulase hydrolysis. The IF of Fe (III)-pretreated bagasse could decrease to 1.35. In this case, the enzymatic digestibility of bagasse approached to 100%.     

Fermentable sugars recovery from grape stalks for bioethanol production

Three different processes were investigated for the recovery of fermentable sugars from grape stalks: autohydrolysis at 121 °C before and after a pre-washing step and acid hydrolysis (2% H₂SO₄ w/w) after a pre-washing step. Moreover, optimal conditions of a charcoal-based purification process were determined by experimental design. All hydrolysates, with their corresponding synthetic liquors were used as fermentation substrates for the production of metabolites by the yeast: Debaryomyces nepalensis NCYC 1026. The main fermentation product was ethanol, where a maximum production of 20.84 g/l, a conversion yield of 0.35 g ethanol/g monomeric sugars and a productivity of 0.453 g/l h were obtained from non-purified autohydrolysate liquor. In all cases, ethanol production and cell growth were better in non-purified liquors than in synthetic liquors. These results could be influenced by the presence of other sugars in the hydrolysates, with higher concentration in non-purified ones.     

Biohydrogen production from pure and natural lignocellulosic feedstock with chemical pretreatment and bacterial hydrolysis

Pretreatment and saccharification of lignocellulosic materials is the key technology affecting the efficiency of cellulosic biohydrogen production. In this work, two pure cellulosic materials (i.e., carboxymethyl-cellulose (CMC) and xylan) were directly hydrolyzed (without pretreatment) by a cellulolytic isolate Cellulomonas uda E3-01 able to release extracellular cellulolytic enzymes. Natural cellulosic feedstock (i.e., sugarcane bagasse) was chemically pretreated prior to the bacterial hydrolysis.A temperature-shift strategy (35 °C for cellulolytic enzymes production and 45 °C for hydrolysis reaction) was used to increase the production of reducing sugars during the bacterial hydrolysis. The hydrolysates of CMC, xylan, and bagasse were efficiently converted to H₂ via dark fermentation with Clostridium butyricum CGS5. The maximum hydrogen yield was 8.80 mmol H₂/g reducing sugar (i.e., 1.58 mol H₂/mol hexose) for CMC, 6.03 mmol H₂/g reducing sugar (i.e., 0.91 mol H₂/mol pentose) for xylan, and 6.01 mmol H₂/g reducing sugar for bagasse.     

Comparison between heterofermentation and autofermentation in hydrogen production from Arthrospira (Spirulina) platensis wet biomass

Hydrogen production from Arthrospira (Spirulina) platensis wet biomass through heterofermentation by the [FeFe] hydrogenase of hydrogenogens (hydrogen-producing bacteria) and autofermentation by the [NiFe] hydrogenase of Arthrospira platensis was discussed under dark anaerobic conditions. In heterofermentation, wet cyanobacterial biomass without pretreatment was hardly utilized by hydrogenogens for hydrogen production. But the carbohydrates in cyanobacterial cells released after cell wall disruption were effectively utilized by hydrogenogens for hydrogen production. Wet cyanobacterial biomass was pretreated with boiling and bead milling, ultrasonication, and ultrasonication and enzymatic hydrolysis. Wet cyanobacterial biomass pretreated with ultrasonication and enzymatic hydrolysis achieved the maximum reducing sugar yield of 0.407 g/g-DW (83.0% of the theoretical reducing sugar yield). Different concentrations (10 g/l to 40 g/l) of pretreated wet cyanobacterial biomass were used as substrate to produce fermentative hydrogen by hydrogenogens, which were domesticated with the pretreated wet cyanobacterial biomass as carbon source. The maximum hydrogen yield of 92.0 ml H₂/g-DW was obtained at 20 g/l of wet cyanobacterial biomass. The main soluble metabolite products (SMPs) in the residual solutions from heterofermentation were acetate and butyrate. In autofermentation, hydrogen yield decreased from 51.4 ml H₂/g-DW to 11.0 ml H₂/g-DW with increasing substrate concentration from 1 g/l to 20 g/l. The main SMPs in the residual solutions from autofermentation were acetate and ethanol. The hydrogen production peak rate and hydrogen yield at 20 g/l of wet cyanobacterial biomass in heterofermentation showed 110- and 8.4-fold increases, respectively, relative to those in autofementation.     

Enhanced enzymatic conversion with freeze pretreatment of rice straw

Production of bioethanol by the conversion of lignocellulosic waste has attracted much interest in recent years, because of its low cost and great potential availability. The pretreatment process is important for increasing the enzymatic digestibility of lignocellulosic materials. Enzymatic conversion with freeze pretreatment of rice straw was evaluated in this study. The freeze pretreatment was found to significantly increase the enzyme digestibility of rice straw from 48% to 84%. According to the results, enzymatic hydrolysis of unpretreated rice straw with 150 U cellulase and 100 U xylanase for 48 h yielded 226.77 g kg⁻¹ and 93.84 g kg⁻¹ substrate-reducing sugars respectively. However, the reducing sugar yields from freeze pretreatment under the same conditions were 417.27 g kg⁻¹ and 138.77 g kg⁻¹ substrate, respectively. In addition, hydrolyzates analysis showed that the highest glucose yield obtained during the enzymatic hydrolysis step in the present study was 371.91 g kg⁻¹ of dry rice straw, following pretreatment. Therefore, the enhanced enzymatic conversion with freeze pretreatment of rice straw was observed in this study. This indicated that freeze pretreatment was highly effective for enzymatic hydrolysis and low environmental impact.     

Dilute oxalic acid pretreatment for biorefining giant reed (Arundo donax L.)

Biomass pretreatment is essential to overcome recalcitrance of lignocellulose for ethanol production. In the present study we pretreated giant reed (Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic acid. The effects of temperature (170-190 °C), acid loading (2-10% w/w) and reaction time (15-40 min) were handled as a single parameter, combined severity. We explored the change in hemicellulose, cellulose and lignin composition following pretreatment and glucan conversion after enzymatic hydrolysis of the solid residue. Two different yeast strains, Scheffersomyces (Pichia) stipitis CBS 6054, which is a native xylose and cellobiose fermenter, and Saccharomyces carlsbergensis FPL-450, which does not ferment xylose or cellobiose, were used along with commercial cellulolytic enzymes in simultaneous saccharification and fermentation (SSF). S. carlsbergensis attained a maximum ethanol concentration of 15.9 g/l after 48 h at pH 5.0, while S. stipitis, at the same condition, took 96 h to reach a similar ethanol value; increasing the pH to 6.0 reduced the S. stipitis lag phase and attained 18.0 g/l of ethanol within 72 h.     

Sugarcane hybrids with original low lignin contents and high field productivity are useful to reach high glucose yields from bagasse

Five sugarcane hybrids plus a reference material were evaluated according to the glucose yields obtained after alkaline-sulfite pretreatment and enzymatic hydrolysis. Sugarcane hybrids with varied original chemical compositions were used to assess how contrasting samples might influence the integrated pretreatment and hydrolysis process. The hydrolysis efficiency of six samples treated at three different chemical loads, suggested that lignin and hemicellulose removals during the pretreatment were not the single factor necessary to reach high cellulose conversion levels in the enzymatic hydrolysis step. Pretreated samples with the highest total acid contents (mainly sulfonic acids) were also the most digestible materials. The glucose yields were heavily dependent not only on the digestibility of the pretreated materials but also on the field productivity of the plants. One of the hybrids, presenting high glucan yields after pretreatment and high digestibility, produced low glucose yields because it presented very low biomass productivity. In contrast, one of the hybrids that presented low glucan yield after pretreatment, but was highly digestible and presented high biomass productivity, provided the highest glucose yields in the data set, producing 4192 and 5629 kg of glucose per hectare after enzymatic hydrolysis for 24 h and 72 h, respectively.     

Biohydrogen production from ricebran using Clostridium saccharoperbutylacetonicum N1-4

Treated ricebran hydrolysate was fermented anaerobically using Clostridium saccharoperbutylacetonicum N1-4 at an initial pH of 6 ± 0.2 and an operating temperature of 30 °C for production of hydrogen. The effects of different pretreatment methods on the liberation of sugar from 100 g of ricebran per litre of medium (distilled water) were investigated. In addition, the effects of the pretreatment method on ricebran hydrolysates of different initial ricebran concentrations on liberated sugar as well as the effects of the initial inoculum concentration, ricebran (substrate) concentration, and FeSO₄·7H₂O concentration on the yield as well as the productivity of hydrogen were investigated. The combination of enzymatic hydrolysis and a boiling pretreatment method produced the most fermentable sugar, 29.03 ± 0.0 g/L from 100 g of ricebran per litre of medium (distilled water), while the amount of sugar liberated by ricebran hydrolysates of different initial ricebran concentrations upon pretreatment monotonically increased with the initial ricebran concentration. The increment in substrate, inoculum, and FeSO₄·7H₂O concentrations had a significantly positive effect (p < 0.05) on both the yield and productivity of hydrogen. The maximum hydrogen gas yield (Y_P/S) and productivity of 3.37 mol-H₂ per mol-sugar consumed and 7.58 mmol/(L h), respectively, were obtained from ricebran hydrolysate with a 100 g/L ricebran concentration (equivalent to 28.59 ± 1.27 g sugar/L). In other experiments, 0.03 g/L FeSO₄·7H₂O and 1.5 g/L inoculum resulted in the best hydrogen gas yield and productivity from ricebran hydrolysates.     

Efficient sugar production from sugarcane bagasse by microwave assisted acid and alkali pretreatment

Sugarcane bagasse represents one of the best potential feedstocks for the production of second generation bioethanol. The most efficient method to produce fermentable sugars is by enzymatic hydrolysis, assisted by thermochemical pretreatments. Previous research was focused on conventional heating pretreatment and the pretreated biomass residue characteristics. In this work, microwave energy is applied to facilitate sodium hydroxide (NaOH) and sulphuric acid (H₂SO₄) pretreatments on sugarcane bagasse and the efficiency of sugar production was evaluated on the soluble sugars released during pretreatment. The results show that microwave assisted pretreatment was more efficient than conventional heating pretreatment and it gave rise to 4 times higher reducing sugar release by using 5.7 times less pretreatment time. It is highlighted that enrichment of xylose and glucose can be tuned by changing pretreatment media (NaOH/H₂SO₄) and holding time. SEM study shows significant delignification effect of NaOH pretreatment, suggesting a possible improved enzymatic hydrolysis process. However, severe acid conditions should be avoided (long holding time or high acid concentration) under microwave heating conditions. It led to biomass carbonization, reducing sugar production and forming ‘humins’. Overall, in comparison with conventional pretreatment, microwave assisted pretreatment removed significant amount of hemicellulose and lignin and led to high amount of sugar production during pretreatment process, suggesting microwave heating pretreatment is an effective and efficient pretreatment method.     

Study on saccharification techniques of seaweed wastes for the transformation of ethanol

Floating residue (FR), a surplus by-product from the alginate extraction process, contains large amount of cellulosic materials. The technical feasibility of FR utilization as a resource of renewable energy was investigated in this paper. The production of yeast-fermentable sugars (glucose) from FR was studied by dilute sulfuric acid pretreatment and further enzymatic hydrolysis. Dilute sulfuric acid pretreatment was conducted by using sulfuric acid at concentration of 0, 0.1, 0.2, 0.5 and 1.0%(w/v) for 0.5, 1.0 and 1.5 h respectively at 121 °C. The system of enzymatic hydrolysis consisted of cellulase and cellobiase. Results showed that FR might be a perfect bioenergy resource, containing high content of cellulose (30.0 ± 0.07%) and little hemicellulose (2.2 ± 0.86%). The acid pretreatment improved the hydrolysis efficiency of cellulase and cellobiase by increasing the reaction surface area of FR and enhanced the final yield of glucose for fermentation. The maximum yield of glucose reached 277.5 mg/g FR under the optimal condition of dilute sulfuric acid pretreatment (0.1% w/v, 121 °C, 1.0 h) followed by enzymatic hydrolysis (50 °C, pH 4.8, 48 h). After fermentation by Saccharomyces cerevisiae at 30 °C for 36 h, the ethanol conversion rate of the concentrated hydrolysates reached 41.2%, which corresponds to 80.8% of the theoretical yield. It indicates that cellulose in seaweed processing wastes including FR is easily hydrolyzed to produce glucose in comparison with that in terrestrial plants. FR shows excellent prospects as a potential feedstock for the production of bioethanol.