Characterization of cell wall structure in dilute acid-pretreated biomass by confocal Raman microscopy and enzymatic hydrolysis

The chemical and ultrastructural properties of cell walls were investigated to determine the effect of dilute acid pretreatment on the hydrolysis of lignocellulosic biomass. Confocal Raman microscopy was used to gain a clear understanding of how dilute acid pretreatments destroy lignocellulosic cell walls. Total fermentable sugar (glucose and xylose) was high in oxalic acid hydrolysate (26.18 g/L) compared to that in sulfuric acid hydrolysate (24.34 g/L). Chemical composition of the pretreated biomass differed slightly according to the acid catalyst used. Oxalic acid pretreatment was effective for enzymatic hydrolysis, with 29.46 g/L of total fermentable sugar after 96 h. Optical microscopy showed that dilute acid pretreatment significantly changed cell wall structure, and broken and crushed cell walls could be clearly seen during pretreatment. Based on confocal Raman peak intensity, the ratio of lignin/cellulose [I(1600)/I(900)] was low for oxalic acid-pretreated biomass compared to sulfuric acid-pretreated biomass.     

Evaluation of bio-hydrogen production using rice straw hydrolysate extracted by acid and alkali hydrolysis

This study was conducted to investigate the properties of hydrolysates obtained from acid and alkali hydrolysis and to evaluate the feasibility of employing them for bio-hydrogen production. High sugar concentrations of 16.8 g/L and 13.3 g/L were present in 0.5% and 1.0% H₂SO₄ hydrolysates, respectively. However, H₂SO₄ hydrolysis resulted in large amounts of short-chain fatty acids (SCFAs) and furan derivatives, which were removed by detoxification. In bio-hydrogen production, 1.0% H₂SO₄ hydrolysate showed a 55.6 mL of highest hydrogen production and 1.14 mol-H₂/mol-hexose equivalent_added of hydrogen yield. In control and 1.0% NaOH hydrolysate, 29.7 mL and 36.9 mL of hydrogen were produced, respectively. Interestingly, relatively high acetate and butyrate production resulted in lactate reduction. Also, NH₄OH hydrolysate produced less than 10 mL of hydrogen. Thus, these results indicate that hydrogen production and metabolite distribution can vary depending on the sugars and by-product composition in the hydrolysate.     

Co-digestion of oil palm trunk hydrolysate with slaughterhouse wastewater for thermophilic bio-hydrogen production by Thermoanaerobacterium thermosaccharolyticm KKU19

The key factors influencing a co-digestion of the oil palm trunk (OPT) hydrolysate with a slaughterhouse wastewater (SHW) to produce hydrogen by Thermoanaerobacterium thermosaccharolyticum KKU19 were investigated. The OPT hydrolysate was obtained by the hydrolysis of OPT by microwave-H₂SO₄ method using 1.56% (w/v) H₂SO₄ and 7.50 min reaction time at 450 W. The Plackett–Burman method was used to screen the key factors that influenced the hydrogen production potential (P_s). Results indicated that initial cell concentration, tCOD/TN (total COD/total nitrogen) ratio and CuSO₄ concentration influenced the P_s. These factors were further optimized using response surface methodology (RSM) with central composite design (CCD). A maximum P_s of 2604 ± 86 mL H₂/L substrate was achieved at an initial cell concentration of 224 mg dry cell/L, tCOD/TN ratio of 49.87 and CuSO₄ concentration of 13.33 mg/L. The main soluble metabolite products were butyric and acetic acids. The P_s obtained when the hydrolysate was supplemented with SHW (2604mL ± 86 mL H₂/L substrate) was comparable to the P_s obtained when it was supplemented with yeast extract at the same tCOD/TN (2802 ± 87 mL H₂/L substrate). This result suggests that SHW can be used to replace the costly nitrogen source.     

Utilization of palm kernel cake as a renewable feedstock for fermentative hydrogen production

Fermentative hydrogen generation was studied using palm kernel cake (PKC) as sustainable cellulosic biomass. PKC was subjected to an acid hydrolysis approach using dilute H₂SO₄ (7% v/v). PKC hydrolysate obtained was then diluted (70%) and used as a substrate for hydrogen generation. Chemical analysis showed that the main fermentable sugars in diluted PKC hydrolysate were glucose, xylose and mannose with the concentrations of 2.75 g/L, 2.60 g/L and 27.75 g/L, respectively. Hydrogen production was carried out by the cultivation of Clostridium acetobutylicum YM1 on PKC hydrolysate. The effect of incubation temperature, the initial pH of culture medium and microbial inoculum size on hydrogen production was studied using a statistical model. The analysis of the model generated showed that the initial pH value of the culture medium and inoculum size had significant effects on the hydrogen production. The study showed that the optimum conditions for the biohydrogen production were 30.57 °C temperature, pH 5.5 and 20% inoculum size. A verification experiment was performed in the optimum conditions determined. Experimental results of the verification test showed that a cumulative hydrogen volume of 1575 ml/L was generated with consuming 2.75 g/L glucose, 2.20 g/L xylose and 16.31 g/L mannose.     

Comparative study on the production of biohydrogen from rice mill wastewater

This study presents the production of biohydrogen from rice mill wastewater. The acid hydrolysis and enzymatic hydrolysis operating conditions were optimized, for better reducing sugar production. The effect of pH and fermentation time on biohydrogen production from acid and enzymatic hydrolyzed rice mill wastewater was investigated, using Enterobacter aerogenes and Citrobacter ferundii. The enzymatic hydrolysis produced the maximum reducing sugar (15.8 g/L) compared to acid hydrolysis (14.2 g/L). The growth data obtained for E. aerogenes and C. ferundii, fitted well with the Logistic equation. The hydrogen yields of 1.74 mol H₂/mol reducing sugar, and 1.40 mol H₂/mol reducing sugar, were obtained from the hydrolyzate obtained from enzymatic and acid hydrolysis, respectively. The maximum hydrogen yield was obtained from E. aerogenes compared to C. ferundii, and the optimum pH for better hydrogen production was found to be in the range from 6.5 to 7.0. The chemical oxygen demand (COD) reduction obtained was around 71.8% after 60 h of fermentation.     

Utilization of excess corn kernels for hydrogen gas biofuel production

Corn kernels are good candidates for production of various value-added products such as gas biofuel, hydrogen due to the carbohydrate-rich composition. In this study, widely grown corn, field corn kernels were dissolved in subcritical water at different temperatures to determine optimal thermal hydrolysis condition. Organic-rich hydrolysate obtained from hydrolysis process was gasified by aqueous-phase reforming (APR) for hydrogen gas production.Since hydrolysis at 200 °C resulted in significantly more total organic carbon release than other temperatures and the lowest amount of insolubilized solid residue. Different concentrations of this hydrolysate (diluted with water at different ratios) were evaluated for high yielding hydrogen gas production. Gasification performance of corn kernels was also compared with lignocellulosic biomass using corn stover as a representative biomass material.The hydrolysate with 2486 mg/L TOC concentration showed the best performance for hydrogen gas production (130 mL H₂/g corn) and left less amount of ungasified solid residue. Corn kernels produced 2.3 times more hydrogen gas compared to corn stover biomass. Thus, corn kernels are promising feed materials for APR process, and excess production of corn can be utilized for hydrogen gas production in higher yield and richer composition.     

Optimization of various pretreatments condition of kenaf core (Hibiscus cannabinus) fibre for sugar production: Effect of chemical compositions of pretreated fibre on enzymatic hydrolysability

In this work, the effects of various pretreatments’ parameters on kenaf core fibre were analyzed statistically and optimized using Response Surface Methodology based on the total glucose yield. The chemical compositions of the pretreated fibres were examined to discuss the effect of pretreatment on the fibre hydrolysability comprehensively. The results showed that estimation model for each pretreatment of kenaf core fibre were polynomial equations. The optimum conditions for water, acid and alkali pretreatments were 170 °C for 45 min, 120 °C for 90 min in 2.0% H₂SO₄ solution and 140 °C for 60 min in 3.0% NaOH solution, respectively. Among the three pretreatments, water pretreatment achieved the highest total glucose yield (25.5%), followed by acid (20.0%) and alkali (18.2%) pretreatments. Based on chemical compositions analysis, both water and acid pretreatments were capable of eliminating almost 100% of hemicellulose with negligible removal of lignin while the alkali pretreatment removed both the lignin and hemicellulose more than 60%. This result revealed that the removal of hemicellulose showed greater influential in enhancing the enzymatic accessibility and hence, hydrolysability of kenaf core fibre.     

The use of acidified palm oil mill effluent for thermophilic biomethane production by changing the hydraulic retention time in anaerobic sequencing batch reactor

The feasibility of thermophilic biomethane production from acidified palm oil mill effluent (POME) was assessed in a 5 L anaerobic sequencing batch reactor (ASBR). The effects of various hydraulic retention time (HRT) (10-1 d) on methane production performance and the stability of ASBR in treating acidified POME were evaluated herein. It was found that the highest methane productivity of 5.65 L CH₄/L/d could be attained at HRT of 2 d. However, the removal of chemical oxygen demand (COD) and volatile fatty acid (VFA) at this HRT is rather low (65-62%) hence making it inefficient to operate at HRT 2 d since most of the contaminants remained in the liquid streams. Thus the most recommended HRT was 3 d with maximum methane productivity of 3.96 L CH₄/L/d with corresponding methane yield of 260.3 L CH₄/kgCOD_removed. The COD removal efficiency at 3 d HRT was 71%, and the VFA consumption was more than 80%. The correlation of total VFA: total alkalinity (TVFA: TA) at HRT of 3 d was found to be 0.1. This recommended HRT of 3 is equally shorter than any previously reported application of POME as a substrate for thermophilic biomethane.     

Combined ethanol and methane production from switchgrass (Panicum virgatum L.) impregnated with lime prior to steam explosion

Pretreatments are crucial to achieve efficient conversion of lignocellulosic biomass to soluble sugars. In this light, switchgrass was subjected to 13 pretreatments including steam explosion alone (195 °C for 5, 10 and 15 min) and after impregnation with the following catalysts: Ca(OH)₂ at low (0.4%) and high (0.7%) concentration; Ca(OH)₂ at high concentration and higher temperature (205 °C for 5, 10 and 15 min); H₂SO₄ (0.2% at 195 °C for 10 min) as reference acid catalyst before steam explosion. Enzymatic hydrolysis was carried out to assess pretreatment efficiency in both solid and liquid fraction. Thereafter, in selected pretreatments the solid fraction was subjected to simultaneous saccharification and fermentation (SSF), while the liquid fraction underwent anaerobic digestion (AD). Lignin removal was lowest (12%) and highest (35%) with steam alone and 0.7% lime, respectively. In general, higher cellulose degradation and lower hemicellulose hydrolysis were observed in this study compared to others, depending on lower biomass hydration during steam explosion. Mild lime addition (0.4% at 195 °C) enhanced ethanol in SSF (+28% than steam alone), while H₂SO₄ boosted methane in AD (+110%). However, methane represented a lesser component in combined energy yield (ethanol, methane and energy content of residual solid). Mild lime addition was also shown less aggressive and secured more residual solid after SSF, resulting in higher energy yield per unit raw biomass. Decreased water consumption, avoidance of toxic compounds in downstream effluents, and post process recovery of Ca(OH)₂ as CaCO₃ represent further advantages of pretreatments involving mild lime addition before steam explosion.     

Hydrogen,alcohols and volatile fatty acids from the co-digestion of coffee waste (coffee pulp,husk, and processing wastewater) by applying autochthonous microorganisms

The objective of this study was to screen the factors that affect H₂, organic acids and alcohols production from coffee waste pretreated in a hydrothermal reactor applying consortium of bacteria and fungi (indigenous from coffee waste) with hydrolytic and fermentative activity. The effects of pH (4.0–7.0), temperature (30–50 °C), agitation (0–180 rpm), headspace (50–70%), percentage of bioaugmentation (without microbial consortium to 20%), concentration of coffee pulp and husk (2–6 g/L), coffee processing wastewater (7-30 gCOD/L) and yeast extract (0–2 g/L) were evaluated using a Plackett-Burman design. The highest H₂ production potential (82 ml H₂) was obtained under the following conditions: 30 °C, 180 rpm, 50% headspace, without bioaugmentation, 2 g/L pulp and husk coffee, 30 gCOD/L coffee processing wastewater and 2 g/L yeast extract. The main soluble products were acetic acid (1956 mg/L), lactic acid (786 mg/L) and ethanol (816 mg/L). Lactobacillus sp., Clostridium sp., Saccharomyces sp. and Kazachstania sp. were the main autochthonous microorganisms identified. Through metagenome functional analysis, enzymes related to lignin, phenol, cellulose, lignocellulose, and pectin degradation were identified, as well as acidogenesis, and H₂ production.     

Continuous production of hydrogen from oat straw hydrolysate in a biotrickling filter

Hydrogen was produced in a biotrickling filter (BF) packed with perlite and fed with oat straw acid hydrolysate at 30 °C. Inlet chemical oxygen demand (COD) from 1.2 to 35 g/L and hydraulic retention time (HRT) between 24 h and 6 h were assayed. With increasing inlet COD or decreasing HRT, H₂ production rate (HPR) increased but H₂ production yield (HY) decreased. Maximum HPR of 81.4 mL H₂/L_reactor h (3.3 mmol H₂/L_reactor h) and HY of 2.9 mol H₂/mol_{hexose consumed} were found at an inlet COD of 0.05 g_COD/L h (HRT 24 h) and 2.9 g_COD/L h (HRT 12 h), respectively. Maximum hydrogen composition in gas was 45 ± 4% (v/v) with CO₂ as balance. Methane was not detected. Maximum HPR and inlet COD used in this work were higher than others reported for reactors with suspended or fixed biomass. However, implementation of strategies for biomass control to avoid reactor clogging is needed.     

Enzymatic hydrolysis and anaerobic biological treatment of fish industry effluent: Evaluation of the mesophilic and thermophilic conditions

Enzymatic hydrolysis and anaerobic treatment of effluent similar to that generated in the fish processing industry were evaluated at 30 °C and 50 °C. Hydrolysis used lipase produced by fungus Penicillium simplicissimum in solid state fermentation with babassu cake as substrate, which has optimal activity at 50 °C. Hydrolysis kinetics was conducted with mixtures of effluent (containing 1500 mg oils and greases/L) and different lipase activities (0–0.67 U/ml of effluent), verifying that with 0.16 U/ml of effluent, 9.69 μmol/ml of free acids were produced after 4 h at 50 °C. Anaerobic biodegradation assays were conducted with effluent submitted to three different treatments: thermophilic (hydrolysis and anaerobic treatment at 50 °C), mesophilic (hydrolysis and anaerobic treatment at 30 °C) and hybrid (hydrolysis at 50 °C and anaerobic treatment at 30 °C). The best results (97.5% of chemical oxygen demand [COD] removal and 105.4 ml CH₄/g COD_removed) were obtained with the hybrid treatment in only 68 h. The thermophilic hydrolysis not only reduced the amount of enzyme and the hydrolysis time but also reduced the time and the cost of mesophilic anaerobic treatment, favoring the application of this treatment on an industrial scale.     

Comparison of thermophilic and hyperthermophilic dark fermentation with subsequent mesophilic methanogenesis in expanded granular sludge bed reactors

Herein, dark fermentation (DF, V = 5.5 L) and subsequent mesophilic methanogenesis (V = 43.5 L) are run as expanded granular sludge bed reactors (EGSB) at thermophilic (υDF = 60 °C) and hyperthermophilic (υDF = 80 °C) temperatures. A synthetic glucose wastewater is run with a 22.5 g/L chemical oxygen demand (COD) and 48–9 h hydraulic retention times (HRTs), giving organic loading rates (OLRs) of 11–60 g COD/L/d for DF. The maximum hydrogen production rate (HPR) is HPR = 3.0 m³/m³/d for HRT = 9 h with a 50 L/kg COD hydrogen yield (HY) and 40 vol% H₂. Methane production rate (MPR) reaches MPR = 2.6 m³/m³/d with 70 vol% CH₄ at HRT = 2.8 d. The highest H₂ yields are HY = 180 L/kg COD with 53 vol% H₂ (thermophilic, HRT = 48 h). Hyperthermophilic temperatures led to lower HPRs (0.7 m³/m³/d) and MPRs (1.6 m³/m³/d). 53% of Thermoanaerobacterium thermosaccharolyticum as an H₂ producer are found. Discoloration of granular sludge from black to white and granule stability was observed in DF.     

Anaerobic fermentative system based scheme for green energy sustainable houses

The green energy sustainable house based on bio-hydrogen and bio-methane energy technologies proposed in this study employs dark fermentation technology to complete a scheme for green energy sustainable house that includes energy production, storage, distribution control, load applications, recycling, waste treatment, and reuse. In order to resolve the problem of wastewater discharge from hydrogen production in green energy sustainable houses, this study proposes wastewater chemical oxygen demand (COD) treatment research, and suggests the use of two-stage anaerobic treatment to produce two types of bio-energy i.e. hydrogen and methane, while simultaneously reducing COD levels.Methane production employed a condensed molasses fermentation solubles (CMS) and hydrogen fermentation tank effluent as a substrate to test the COD reducing efficiency and overall efficiency of methane production. It was found that if CMS is used during the hydrolysis and acidogenesis stages, the maximum carbohydrate degradation rate will be approximately 70% (F/M ratio of 1.9-2.3), and the COD removal rate will increase from 15 to 20% (F/M ratio of 1.9-2.3) to 68% (F/M ratio of 0.5). This study showed that the total gas (H₂ and CH₄) production yield from effluent of hydrogen fermentation tank (56.2 KJ/mol substrate) is greater than the value for CMS.In this study, a 3.2 m³ anaerobic hydrogen reactor is evaluated to provide a family with 3-4 kW of power. When acclimatization is performed under conditions of 20 g COD/L substrate and hydraulic retention time (HRT) of 8 h, the COD removal rate can reach approximately 50%. If a methane-generating reactor with a 95% COD removal rate is used to degrade effluent from the hydrogen reaction tank, it will be possible to reduce the COD of organic effluent to under 500 mg/L. Since this water quality is not far from that of ordinary untreated household wastewater (approximately 300-500 mg COD/L), the effluent can be discharged into a community sewer system and treated in a community sewage treatment facility.     

Dark fermentative hydrogen production from simple sugars and various wastewaters by a newly isolated Thermoanaerobacterium thermosaccharolyticum SP-H2

The hydrogen-producing bacterium SP-H2 was isolated from a thermophilic acidogenic reactor inoculated with municipal sewage sludge and processing a carbohydrate-rich simulated food waste. Based on the 16S rRNA gene sequence, the bacterium was identified as Thermoanaerobacterium thermosaccharolyticum. The maximum growth rate was observed at 55–60 °C and pH 7.5. The H₂-producing activity of the bacterium was studied using mono-, di- and tri-saccharides related to both hexoses (maltose, glucose, mannose, fructose, lactose, galactose, sucrose, raffinose, cellobiose) and pentoses (xylose and arabinose), as well as using real wastewaters (cheese whey, confectionery wastewater, sugar-beet processing wastewater). The highest H₂ yield was observed during dark fermentation (DF) of maltose (1.91 mol H₂/mol hexose or 77.8 mmol H₂/L). The maximum H₂ production rate was observed during DF of xylose (13.3 ml H₂/g COD/h) and cellobiose (2.47 mmol H₂/L/h). The main soluble metabolite products were acetate, ethanol and butyrate. The acetate concentration had a statistically significant positive correlation with the H₂ content in biogas and the specific H₂ yield. Based on the results of the correlation analysis, it was tentatively assumed that in the formic acid (mixed-acid) type fermentation, the rate of H₂ production was higher than in the butyric acid type fermentation. With regard to real wastewater, cheese whey and confectionery wastewater were distinguished by a higher H₂ yield (152 ml H₂/g COD) and H₂ production rate (0.57 mmol H₂/L/h), respectively. The highest concentrations of confectionery wastewater and cheese whey, at which the DF process took place, were 5915 and 7311 mg COD/L, respectively. At the same time, SP-H2 dominated in the microbial community, despite the presence of indigenous microorganisms in wastewater. Thus, T. thermosaccharolyticum SP-H2 is a promising strain for DF of carbohydrate-rich unsterile wastewater under thermophilic conditions.     

Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters

The objective of this study was to maximize the hydrolysis and acidification of sugar-beet processing wastewater and beet pulp for volatile fatty acid (VFA) production through acidogenic anaerobic metabolism. Experiments were conducted to determine the optimum operational conditions (HRT, waste-mixing ratio and pH) for effective acidification in daily-fed, continuously mixed anaerobic reactors. For this purpose, reactors were operated at 35 ± 1 °C with different combinations of HRT (2-4 days), wastewater-pulp mixing ratios (1:0-1:1, in terms of COD) and pH ranges (5.7-7.5). Increased OLRs, resulting from pulp addition, increased the amount of acidification products (VFAs) which led to relatively low operational pH values (5.7-6.8). In this pH range, methanogenic activity was successfully inhibited and the lowest methane percentages (5.6-16.3%) were observed in the produced biogas. The optimum operational conditions were determined to be 2-day HRT and 1:1 waste mixing ratio (in terms of COD) without external alkalinity addition. These operational conditions led to the highest tVFA concentration (3635 ± 209 mg/L as H-Ac) with the acidification degree of 46.9 ± 2.1%.     

Biotoxicity assessment and lignocellulosic structural changes of phosphoric acid pre-treated young coconut husk hydrolysate for biohydrogen production

Major sugar constituents in young coconut husk were found to be glucans (0.30 g/g husk), while xylans were 0.10 g/g husk. Pre-treatments were carried out using phosphoric acid with dried coconut husk powder under steam heating. The effect of phosphoric acid on coconut husk hydrolysis was observed using acid concentrations of 0%, 1%, 5% and 10% (v/v). Soluble sugar concentration in hydrolysate was increasing proportional to acid concentration, as the total recovered solid decreases. FTIR and XRD analysis showed that acid hydrolysis led to the disruption of internal chemical bonds, causing coconut husk structural sugars to be released into the hydrolysate. Highest soluble sugar concentration, 29.9 g/L with a total suspended solid of 75.1 g/L, was obtained when the coconut husk was pre-treated with 10% phosphoric acid, and can be utilised for biohydrogen fermentation. Biotoxicity testing of the hydrolysates shows that half-maximal inhibition concentration of phosphoric acid was around 4.41% for a 24-h incubation and 3.80% for a 96-h incubation.     

Biohydrogen and 5-aminolevulinic acid production from waste barley by Rhodobacter sphaeroides O.U.001 in a biorefinery concept

The production of biohydrogen and 5-aminolevulinic acid (5-ALA) by Rhodobacter sphaeroides O.U.001 was investigated in a biorefinery concept. Waste barley was used as a substrate after acid hydrolysis. The hydrolysate was analyzed in terms of its total simple sugar, organic acid, ammonium, element and total phenol contents. Four different growth media having 5 g/L, 7 g/L, 9 g/L and 11 g/L sugar content were prepared using the waste barley hydrolysate to produce biohydrogen and 5-ALA. The increased sugar concentrations resulted in higher cell density and hydrogen accumulation. Accordingly, the highest cell density (OD₆₆₀: 1.78) and hydrogen production (0.4 L H₂/L culture) were observed in the 11 g/L sugar-containing medium. A 67.4 μM 5-ALA was produced upon vitamin B₁₂ and levulinic acid additions. These results showed that waste barley can be used as a substrate for R. sphaeroides for biohydrogen and 5-ALA production within a biorefinery concept.     

Treatment of dairy wastewater using anaerobic and solar photocatalytic methods

The present study was aimed to treat the dairy wastewater by using anaerobic and solar photocatalytic oxidation methods. The anaerobic treatment was carried out in a laboratory scale hybrid upflow anaerobic sludge blanket reactor (HUASB) with a working volume of 5.9 L. It was operated at organic loading rate (OLR) varying from 8 to 20 kg COD/m³ day for a period of 110 days. The maximum loading rate of the anaerobic reactor was found to be 19.2 kg COD/m³ day and the corresponding chemical oxygen demand (COD) removal at this OLR was 84%. The anaerobically treated wastewater at an OLR of 19.2 kg COD/m³ day was subjected to secondary solar photocatalytic oxidation treatment. The optimum pH and catalyst loading for the solar photochemical oxidation was found to be 5 and 300 mg/L, respectively. The secondary solar photocatalytic oxidation using TiO₂ removed 62% of the COD from primary anaerobic treatment. Integration of anaerobic and solar photocatalytic treatment resulted in 95% removal of COD from the dairy wastewater. The findings suggest that anaerobic treatment followed by solar photo catalytic oxidation would be a promising alternative for the treatment of dairy wastewater.     

A novel staggered hybrid SSF approach for efficient conversion of cellulose/hemicellulosic fractions of corncob into ethanol

The following study reports bioconversion of corncob into ethanol using hybrid approach for co-utilization of dilute acid hydrolysate (pentose rich stream) and hexose rich stream obtained by enzymatic saccharification employing commercial cellulase Cellic CTec2 as well as in-house cellulase preparations derived from Malbranchea cinnamomea, Scytalidium thermophilium and a recombinant Aspergillus strain. Acid hydrolysis (1% H₂SO₄) of corncob at 1:15 solid liquid ratio led to removal of 80.5% of hemicellulosic fraction. The solid glucan rich fraction (63.5% glucan, 8.3% pentosans and 27.9% lignin) was hydrolysed at 10% substrate loading rate with different enzymes for 72 h at 50 °C resulting in release of 732 and 535 (mg/g substrate) total sugars by Cellic CTec2 and M. cinnamomea derived enzymes, respectively. The fermentation of enzyme hydrolysate with co-culture of Saccharomyces cerevisiae and Pichia stipitis added in sequential manner resulted in 3.42 and 2.50% (v/v) ethanol in hydrolysate obtained from commercial Cellic CTec2 and M. cinnamomea, respectively. Employing a hybrid approach, where dilute acid hydrolysate stream was added to solid residue along with enzyme Cellic CTec2 during staggered simultaneous saccharification and fermentation at substrate loading rate of 15% resulted in 252 g ethanol/kg corncob.