Maximum Ethanol Concentration Research Articles

Two-step pH regulating ethanol production through continuous CO/CO2 gas fermentation by mixed bacteria from rabbit faeces

Mixed bacterial syngas fermentation is a promising carbon-neutral method for producing acetic acid and ethanol. However, the bacterial community and metabolic pathways were different in the growth and ethanol production stages, whereas the activity of the bacterial community greatly depended on the pH of the culture. In this study, the effect of pH on syngas fermentation performance and microbial community composition under continuous gas supply was investigated. The mixed bacteria grew fastest at a pH of 7, while a constant pH of 6 led to the highest ethanol concentration of 5.15 g L−1, which was 160 % higher than that at pH 7. Based on this, a two-step pH regulation method was proposed in this study to improve the ethanol production. Initially, the culture pH was maintained at 7 to create optimal growth conditions. Once bacterial density stabilized, it was then changed to a pH 6 to promote ethanol production. By doing this, compared with the control group, the maximum ethanol concentration (5.85 g L−1) increased by 148.9 %, the ethanol production rate (2.41 g L−1 d−1) increased by more than 8 times. This two-step pH regulation method ensured a high bacterial density and effectively stimulated ethanol production during syngas fermentation.

A cellulosomal yeast reaction system of lignin-degrading enzymes for cellulosic ethanol fermentation.

Biofuel production from lignocellulose feedstocks is sustainable and environmentally friendly. However, the lignocellulosic pretreatment could produce fermentation inhibitors causing multiple stresses and low yield. Therefore, the engineering construction of highly resistant microorganisms is greatly significant. In this study, a composite functional chimeric cellulosome equipped with laccase, versatile peroxidase, and lytic polysaccharide monooxygenase was riveted on the surface of Saccharomyces cerevisiae to construct a novel yeast strain YI/LVP for synergistic lignin degradation and cellulosic ethanol production. The assembly of cellulosome was assayed by immunofluorescence microscopy and flow cytometry. During the whole process of fermentation, the maximum ethanol concentration and cellulose conversion of engineering strain YI/LVP reached 8.68g/L and 83.41%, respectively. The results proved the availability of artificial chimeric cellulosome containing lignin-degradation enzymes for cellulosic ethanol production. The purpose of the study was to improve the inhibitor tolerance and fermentation performance of S. cerevisiae through the construction and optimization of a synergistic lignin-degrading enzyme system based on cellulosome.

Bioethanol production from sugarcane molasses by co-fermentation of Saccharomyces cerevisiae isolate TA2 and Wickerhamomyces anomalus isolate HCJ2F-19

PurposeCo-culturing is a widely used method to improve bioethanol production from biomass enriched in fermentable sugars. This study aims to produce bioethanol from sugarcane molasses by simultaneous co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F-19.MethodsResponse surface methodology (RSM) based on the central composite design (CCD) was employed to optimize fermentation conditions, including mixing rate (110–150 rpm), temperature (25–35 °C), molasses concentration (25–35 obrix), and incubation time (36–72 h). The ethanol concentration was analyzed using HPLC equipped with a UV detector.ResultsThe monocultureS. cerevisiae isolate TA2 produced 17.2 g.L−1 of ethanol, 0.33 g.g−1 of ethanol yield, and 0.36 g.L−1.h−1 of productivity compared to W. anomalus isolate HCJ2F that produced 14.5 g.L−1, 0.30 g.g−1 and 0.28 g.L−1.h−1 ethanol, ethanol yield, and productivity under laboratory conditions, respectively. In comparison to single cultures of S. cerevisiae TA2 and W. anomalus HCJ2F, the co-fermentation using both isolates showed an increased ethanol yield of 29% and 53% compared to the single species fermentations, respectively. The results showed that the growth of W. anomalus HCJ2F-19 and S. cerevisiae TA2 was not influenced by each other during the co-fermentation process. The one variable at a time optimization (OVAT) analysis resulted in an ethanol concentration of 26.5 g.L−1 with a specific yield and productivity of 0.46 g.g−1, 0.55 g.L−1.h−1, respectively, at pH 5.5, 25 obrix, 48 h, 150 rpm, 30 °C, 60:40 inoculum ratio, and 10% overall inoculum size. The maximum ethanol concentration of 35.5 g.L−1 was obtained by co-fermentation using the RSM-CCD tool at 30 obrix, 30 °C, 54 h, and 130 rpm.ConclusionThe results suggested that the co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F improves bioethanol production from sugar cane molasses under optimum fermentation conditions.

Sustainable energy enhancement strategy from Chlorella vulgaris microalgae biomass resource

ABSTRACT Growing demand for renewable and sustainable energy sources has prompted research into bioethanol production as a viable alternative to hydrocarbon fuel for automobile engines. Based on their high carbohydrate content, Chlorella vulgaris microalgae were chosen for this study as a feasible biomass for bioethanol synthesis. After conducting microwave-based acid hydrolysis with varying acid concentrations of sulfuric acid (H2SO4) for 1–15 min, this study found that 3% H2SO4 for 5 min yielded the highest yield of reducing sugar (6.77 g/L). In this work, the RSM approach of central composite design (CCD) was utilized for modeling and optimization of ethanol fermentation and the MATLAB Simulink approach was employed for the simulation of ethanol fermentation. This study compared the effects of using Saccharomyces cerevisiae yeast for fermentation at different fermentation times (12 to 48 h), temperatures (28 to 32°C), and size of inoculum (0.5–1.5 g/L). Based on the actual and predicted results, the best conditions for fermentation were 36 h of time, 30°C of temperature, and 1.5 g/L of inoculum size. This gave the maximum ethanol concentration of 3.31 g/L. Furthermore, the RSM method provides minimum error and maximum R2 value results for ethanol production compared to MATLAB simulation prediction (MSP). In addition, residue biomass from biofuel production is evaluated for its suitability for a further form of biofuel production. This research explores the opportunities for zero-waste biomass utilization in the development of biofuels.

Cell disruption of Chlorella sp. and Ecklonia maxima biomass for bioethanol production using Saccharomyces cerevisiae

The demand for bioethanol has increased over the years due to the high costs of fossil fuels, which have been associated with environmental deterioration, leading to the need for cheaper and cleaner biofuel sources. To address this issue, this study investigated micro (Chlorella sp.) and macroalgal (Ecklonia maxima) biomass cell disruption for subsequent bioethanol production using Saccharomyces cerevisiae. Different biomass concentrations of 1.25, 2.5, 3.75 and 5%w/v were prepared, and cell disrupted using ultrasonication and steam extraction for 10, 20, 30 and 40 mins. The samples were analysed for reducing sugar concentrations where the steam-extracted samples produced the highest reducing sugars of 8980 mg/L and 1800 mg/L for Chlorella sp. and E. maxima biomasses respectively. The extracts from ultrasonication and steam extraction were fermented for a period of 96 h where the steam-extracted extracts produced the highest ethanol concentrations from Chlorella sp. and E. maxima biomasses, at the maximum ethanol concentrations of 7 300 mg/L and 689.2 mg/L respectively. The findings of this paper showed that steam extraction is a preferred biomass pretreatment method since its extracts yielded higher ethanol concentrations while the ultrasonicated extracts produced lower ethanol concentrations.

Ethanol production from sugarcane bagasse by modified PDMS membrane in a membrane bioreactor: pervaporation technique

AbstractBACKGROUNDBioethanol is considered a highly promising alternative to fossil fuels due to its derivation from renewable sources. Reducing the disadvantages of conventional fermentation requires removing the product from the fermentation broth after its formation. Therefore, coupling the membrane separation with a biological process in a single unit leads a reduction of substrate and product inhibitions.RESULTSIn this work, bioethanol production was investigated in a membrane bioreactor (MBR) with sugarcane bagasse (lignocellulose waste) as a renewable source by the sulfuric acid hydrolysis process. Firstly, the optimum conditions to produce the maximum amount of sugar by acid hydrolysis were determined. Second, the membrane bioreactor and pervaporation unit equipped with poly(dimethyl siloxane) carbon nanotube/Tetrazole membrane (PDMS‐CNT/Tetrazole) was fabricated. Third, bioethanol production in a conventional batch reactor (CBR) and the novel MBR was implemented. The outcomes of the two kinds of reactors were then compared. The results illustrated that the optimum conditions for acid hydrolysis are at a temperature of 199.4 °C, an operation time of 30.77 min, and an acid concentration of 1.12%. The obtained data shows that the ethanol production in MBR was increased by 103.6% over conventional fermentation. Furthermore, the pervaporated ethanol concentration was higher than that of the broth because of the high membrane selectivity, where a maximum ethanol concentration of 165.7 g L−1 in the cold trap was achieved.CONCLUSIONFinally, the results illustrate that the MBR can decrease the cell density growth rate and dominate any substrate and product inhibitions, while keeping process productivity for ethanol quite high. © 2024 Society of Chemical Industry (SCI).

Experimental Insights into the Fermentation of Pyro-Syngas to Ethanol in a Semi-Batch and Continuous Stirred Bioreactor with Mathematical Modelling and Optimization

Syngas fermentation can play an important role in implementing the concept of biorefinery as it can serve as a platform to convert high-lignin biomass to biofuels. For the utilization of this process in commercial scale, the generation of an experimental database supported by a deterministic mathematical model and optimization is necessary. In this study, a locally isolated clostridial consortium, UACJUChE1, was used to convert pyro-syngas to ethanol and acetic acid. Mathematical models were developed and validated for a 3 L stirred and gas-sparged bioreactor operated in both semi-batch and continuous modes. The volumetric productivity of ethanol was correlated with the dilution rate and the gas residence time. The performance of the bioreactor, run in both semi-batch and continuous modes, was optimized using response surface methodology. For the semi-batch operation, a maximum ethanol concentration of 13.122 g/L after 30 h operation was achieved at optimum values of pyrolysis temperature, ratio of gas to liquid volume (VG/VL), and volumetric gas flow rate of 648 °C, 0.46, and 6.7 L/h respectively. For continuous operation, a maximum ethanol concentration of 29.450 g/L after 300 h is obtained at optimum values of VG/VL and ratio of gas to liquid volumetric flow rate of 0.28 and 335.148, respectively.

Bioethanol production from deproteinized cheese whey powder by local strain isolated from soured milk: influence of operating parameters

ABSTRACT In this paper, a local isolated yeast strain was studied for bioethanol production using protein-free cheese whey powder (CWP) in batch alcoholic fermentation experiments. Ethanol tolerance tests were performed with different ethanol concentrations (from 0% to 20%). The maximum ethanol tolerance obtained for our strain was 5% (v/v). The influence of initial lactose concentration, temperature and pH on fermentation kinetic was studied. For initial lactose concentration ranging from 57.5 to 260 gL−1, the highest ethanol production 34.8 gL−1 was obtained at 109 gL−1 initial lactose concentration corresponding to 0.413 gg−1 ethanol yield (YP/S); (While it was noticed less ethanol production, namely 0.178 g g−1) at a higher initial whey sugar concentration of 260 gL−1. The effect of the initial pH on the fermentation was studied at three different values: 3, 4 and 5. The ethanol production reached a maximum of 22 g L−1 with a lactose consumption of 77.62% at pH 4. However, an observed decrease occurred in ethanol production and lactose consumption at pH 3, with values of 10.34 gL-1 and 24.46%, respectively. For the fermentation conducted at the three temperatures of 37°C, 40°C and 43°C, the maximum ethanol production and lactose consumption were 34.82 gL-1 and 80.75%, respectively, achieved at 37°C. The experimental data was analyzed using the Gompertz model to obtain the following kinetic parameters: the maximum ethanol concentration (Pm) was found to be 36.97 gL-1, the maximum ethanol production rate (rp,m) was 0.402 gL−1h−1 and the lag phase (tl) was 10.8 h. The comparison of the isolated Kluyveromyces marxianus TXID4911 strain with the reference strain Kluyveromyces marxianus DSM 5421, showed a relatively close ethanol yield (YP/S) 0.415 and 0.505 gg,−1 respectively.

Application of Aromatic Ring Quaternary Ammonium and Phosphonium Salts–Carboxylic Acids-Based Deep Eutectic Solvent for Enhanced Sugarcane Bagasse Pretreatment, Enzymatic Hydrolysis, and Cellulosic Ethanol Production

Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors leads to a more pronounced enhancement of lignin removal. In this study, six DES systems were prepared using lactic acid (LA)/acetic acid (AA)/levulinic acid (LEA) as hydrogen bond donors (HBD), along with two independent hydrogen bond acceptors (HBA) (benzyl triethyl ammonium chloride (TEBAC)/benzyl triphenyl phosphonium chloride (BPP)) to evaluate their ability to break down sugarcane bagasse (SCB). The pretreatment of the SCB (raw material) was carried out with the above DESs at 120 °C for 90 min with a solid–liquid ratio of 1:15. The results indicated that an increase in the number of aromatic rings may result in steric hindrance during DES pretreatment, potentially diminishing the efficacy of delignification. Notably, the use of the TEBAC:LA-based DES under mild operating conditions proved highly efficient in lignin removal, achieving 85.33 ± 0.52% for lignin removal and 98.67 ± 2.84% for cellulose recovery, respectively. The maximum digestibilities of glucan (56.85 ± 0.73%) and xylan (66.41 ± 3.06%) were attained after TEBAC:LA pretreatment. Furthermore, the maximum ethanol concentration and productivity attained from TEBAC:LA-based DES-pretreated SCB were 24.50 g/L and 0.68 g/(L·h), respectively. Finally, the comprehensive structural analyses of SCB, employing X-rays, FT-IR, and SEM techniques, provided valuable insights into the deconstruction process facilitated by different combinations of HBDs and HBAs within the DES pretreatment.

Potato peel waste fermentation by Rhizopus oryzae to produce lactic acid and ethanol.

Potato peel waste (PPW), a zero-value by-product generated from potato processing, is a promising fermentation substrate due to its large quantity of starch, nonstarch polysaccharides, lignin, protein, and lipid. Rhizopus oryzae is a filamentous fungus that is mainly known as a lactic acid producer and can ferment various agro-wastes. This study aimed to use R. oryzae for the fermentation of PPW. A series of batch fermentations were conducted to investigate the effects of different PPW loading rates (2%-8%) and particle sizes (0-4 mm). Under an initial PPW loading rate of 8% and particle size of 1-2 mm, the maximum ethanol (18.83 g/L) and lactic acid (3.14 g/L) concentrations, the highest ethanol (9.41 g/L·day) and lactic acid (1.89 g/L·day) average production rates were obtained. Under these conditions, the yield of ethanol and lactic acid was 0.235 g/gPPW and 0.039 g/gPPW, respectively. R. oryzae was shown to utilize PPW as a substrate to produce value-added bioproducts such as ethanol (major product) and lactic acid.

Ethanol Kinetics in the Human Brain Determined by Magnetic Resonance Spectroscopy.

In many parts of the world, ethanol is a widely consumed substance that displays its effect in the brain, the target organ for desired, but also negative impact. In a previous study, the ethanol concentrations were analyzed in different regions of the brain by magnetic resonance spectroscopy (MRS). In this study, the same method is used to demonstrate the kinetics of the ethanol concentration in the human brain after oral ethanol uptake. A drinking study was performed with 10 healthy participants. After the uptake of ethanol in a calculated amount leading to a plasma ethanol concentration of 0.92 g/L (19.95 mM corresponding to a blood ethanol concentration of 0.7 g/kg), brain ethanol concentrations were continuously measured by means of MRS on a 3 Tesla human magnetic resonance imaging (MRI) system. For the data acquisition a single-voxel sLASER sequence was used, with the volume of interest located in the occipital cortex. Intermittently, blood samples were taken and plasma was analyzed for ethanol using headspace gas chromatography with flame ionization detection (HS-GC-FID). The obtained MRS brain ethanol curves showed distinct inter-individual differences; however, a good intra-individual correlation of plasma and brain ethanol concentrations was observed. The results suggest a rapid equilibration between blood and brain. The ethanol concentrations measured in the brain were substantially lower than the measured plasma ethanol results, suggesting an MRS visibility of about 63% for ethanol in brain tissue. The maximum individual ethanol concentrations in the brain (normalized to water content) ranged between 7.1 and 14.1 mM across the cohort, while the highest measured plasma concentrations were in the range between 0.35 g/L (9.41 mM) and 0.95 g/L (20.52 mM).

Optimization Condition for Ethanol Production from Sweet Sorghum Juice by Recombinant Zymomonas mobilis Overexpressing groESL Genes

High-temperature ethanol fermentation (HTEF) using high-potential thermotolerant ethanologenic microorganisms is a promising platform for ethanol production in tropical or subtropical areas. This study aims to evaluate the ethanol production potential of recombinant Zymomonas mobilis R301 overexpressing groESL genes under normal and high-temperature conditions and the expression of genes involved in the heat shock response and ethanol production pathway during ethanol fermentation using sweet sorghum juice (SSJ) as feedstock. Growth characterization analysis revealed that the recombinant Z. mobilis R301 exhibited multi-stress tolerance toward heat, acetic acid, and furfural. Based on the statistical experimental design, the optimum conditions for ethanol production from SSJ by the recombinant R301 at 30 °C were a sugar concentration of 171.67 g/L, cell concentration of 9.42% (v/v), and yeast extract concentration of 10.89 g/L, while those at 40 °C were a sugar concentration of 199.48 g/L, yeast extract concentration of 10.88 g/L, MgSO4 concentration of 1.05 g/L, and initial pH of 6.8. The maximum ethanol concentrations and productivities achieved in this study were 63.26 g/L and 1.17 g/L.h at 30 °C and 58.62 g/L and 1.22 g/L.h at 40 °C. The overexpression of the groES and groEL genes and upregulation of other heat shock-responsive genes at 40 °C enhanced cell growth, viability, and fermentation capacity of recombinant Z. mobilis R301 under heat stress. The current study demonstrated that recombinant Z. mobilis R301 exhibited high potential for ethanol production from SSJ or other sugar-based raw materials under high-temperature conditions.

Comparison of marine and rushton impeller in high solid loading of two-step pretreated oil palm trunk using simultaneous saccharification and fermentation for ethanol production

Substrate loading enhancement in fermenter generates difficulty in mixing that results in low ethanol yield owing to insufficient mass transfer. Thus, this study evaluated the efficiency of a six-blade Rushton turbine and a three-blade marine type propeller in a 3 L stirred tank bioreactor (STBR) by using steam exploded and alkaline pretreated oil palm trunk (OPT) fibers in a unique batch and fed-batch strategy. The fed-batch began with 5% (w/v) solid loading and after 12 h of simultaneous saccharification and fermentation (SSF) reaction, 2.5% (w/v) solid was added in the bioreactor with 6 h interval. The marine and Rushton impellers were compared at 5% (w/v) batch and 20% (w/v) fed-batch SSF, using agitation rate of 100 rpm. At 5% (w/v) solid loading, the highest ethanol concentration and theoretical yield were 15.66 ± 1.71 g/L and 61.69 ± 2.34%, and 12.10 ± 0.98 g/L and 54.01 ± 3.52%, respectively for marine and Rushton impeller. At high solid loading (20% w/v), the marine impeller achieved maximum ethanol concentration of 41.33 ± 2.02 g/L at 72 h of fermentation, with a low power consumption of 54.73 kW. The Rushton impeller resulted in ethanol concentration of 39.08 ± 1.47 g/L at 96 h of fermentation with relatively higher power consumption of 83.62 kW. The marine impeller is therefore efficient with the fed-batch strategy.

Pilot-scale bioethanol production from the starch of avocado seeds using a combination of dilute acid-based hydrolysis and alcoholic fermentation by Saccharomyces cerevisiae

BackgroundA processing methodology of raw starch extraction from avocado seeds (ASs) and a sequential hydrolysis and fermentation bioprocess in just a few steps was successfully obtained for the bioethanol production by a single yeast Saccharomyces cerevisiae strain and this research was also to investigate the optimum conditions for the pretreatment of biomass and technical procedures for the production of bioethanol. It successfully resulted in high yields and productivity of all the experiments from the laboratory scale and the pilot plant. Ethanol yields from pretreated starch are comparable with those in commercial industries that use molasses and hydrolyzed starch as raw materials.ResultsBefore the pilot-scale bioethanol production, studies of starch extraction and dilute sulfuric acid-based pretreatment was carefully conducted. The amount of starch extracted from dry and fresh avocado seed was 16.85 g ± 0.34 g and 29.79 ± 3.18 g of dry starch, representing a yield of ∼17% and 30%, respectively. After a dilute sulfuric acid pretreatment of starch, the released reducing sugars (RRS) were obtained and the hydrolysate slurries containing glucose (109.79 ± 1.14 g/L), xylose (0.99 ± 0.06 g/L), and arabinose (0.38 ± 0.01 g/L). The efficiency of total sugar conversion was 73.40%, with a productivity of 9.26 g/L/h. The ethanol fermentation in a 125 mL flask fermenter showed that Saccharomyces cerevisiae (Fali, active dry yeast) produced the maximum ethanol concentration, pmax at 49.05 g/L (6.22% v/v) with a yield coefficient, Yp/s of 0.44 gEthanol/gGlucose, a productivity or production rate, rp at 2.01 g/L/h and an efficiency, Ef of 85.37%. The pilot scale experiments of the ethanol fermentation using the 40-L fermenter were also successfully achieved with essentially good results. The values of pmax,Yp/s, rp, and Ef of the 40-L scale were at 50.94 g/L (6.46% v/v), 0.45 gEthanol/gGlucose, 2.11 g/L/h, and 88.74%, respectively. Because of using raw starch, major by-products, i.e., acetic acid in the two scales were very low, in ranges of 0.88–2.45 g/L, and lactic acid was not produced, which are less than those values in the industries.ConclusionsThe sequential hydrolysis and fermentation process of two scales for ethanol production using the combination of hydrolysis by utilizing dilute sulfuric acid-based pretreatment and fermentation by a single yeast Saccharomyces cerevisiae strain is practicable and feasible for realistic and effective scale-up strategies of bioethanol production from the starch of avocado seeds.

Ethanol and Methane Production from the Organic Fraction of Municipal Solid Waste in a Two-Stage Process

In the present study, the OFMSW was utilized for ethanol and methane production in a two-stage process. First, the OFMSW was fermented by adjusting different levels of total solids (10%, 20%, and 29%) and a yeast dose (6, 12, and 24 g/kgOFMSW) for bioaugmentation with Saccharomyces cerevisiae. A control treatment without bioaugmentation was used for benchmarking. In the self-fermentation of the OFMSW with its indigenous microbiota, lactic acid was mainly produced, followed by ethanol and acetic acid, where a maximum ethanol production of 113 ± 2 gCOD/kgTS, corresponding to 10.8 ± 0.4 g/L, at 20% of total solids was observed. The results showed that in all treatments with bioaugmentation, regardless of the content of total solids, the main metabolites were ethanol, lactic acid, and acetic acid, which represented more than 95% of the total metabolites. The ethanol concentration was increased by increasing the total solids and the yeast dose. The highest ethanol production was 407 ± 3 gCOD/kgTS with the bioaugmentation of 24 g/kgOFMSW and 20% of total solids, whereas the maximum ethanol concentration of 43.4 ± 0.1 g/L was obtained with bioaugmentation of 12 g/kgOFMSW and 29%. The methane potential of the raw OFMSW was 329 ± 5 NL-CH4/kgVS, whereas the solid digestates resulting from the fermentation exhibited similar or even higher methane yields than raw OFMSW. A maximum methane potential of 464 ± 2 NL-CH4/kgVS from the solid digestate obtained after fermentation of the OFMSW with bioaugmentation of 6 g/kgOFMSW of yeast and 10% of total solids was achieved. Thus, large amounts of ethanol and methane were achieved without the application of pretreatment and/or enzymatic hydrolysis, which implies a low-cost alternative for the production of biofuels.

SACARIFICACIÓN ENZIMÁTICA DE BAGAZO DE CAÑA DE AZÚCAR PRETRATADO CON PEROXIDO DE HIDROGENO PARA LA PRODUCCIÓN DE BIOETANOL

<p><strong>Background.</strong> Sugarcane (<em>Saccharum officinarum</em> L.) is one of the main crops in Mexico; during the harvest 2021-2022, 54.6 million tons of raw milled sugarcane were industrialized, ranking sixth in production worldwide. However, during processing, several products and co-products are generated, including sugarcane bagasse, that is used to produce electricity by combustion, converting nearly 25% of its weight into greenhouse gases and generating environmental problems. For this reason, it is necessary to design processes aligned with the axes of sustainable development (environmental, social and economic) to promote valorization and diversification. <strong>Objective</strong>. To determine the effect of two pretreatments on the enzymatic saccharification of sugarcane bagasse for its subsequent conversion to bioethanol. <strong>Methodology.</strong> The production of enzymatic extracts by solid state fermentation (SSF) was carried out using sugarcane bagasse as support-substrate and autochthonous fungal strains as inoculum. For the enzymatic saccharification the sugarcane bagasse was pretreated with hydrogen peroxide and microwaves, for the hydrogen peroxide pretreatment the variables time (1, 3 and 6 h), ratio mL of peroxide per gram of bagasse (16. 6:1, 33.3:1 and 100:1), temperature (26, 50 and 70°C) and peroxide concentration (1, 3 and 5%); and for microwave pretreatment the variables microwave power (p30, p50 and p80) and time (5 and 10 min) were evaluated. For the enzymatic saccharification, enzymatic extracts produced by SSF and bagasse pretreated with hydrogen peroxide were used. Finally, fermentable sugars obtained from the enzymatic saccharification of sugarcane bagasse were used as a unique carbon source in alcoholic fermentation system. <strong>Results.</strong> The SSF results showed the presence of cellulase (2 U/g) and xylanase (61 U/g) activity. On the other hand, the results of pretreatment of sugarcane bagasse with hydrogen peroxide indicated that the best conditions were 100 mL of 3% hydrogen peroxide per gram of sugarcane bagasse at 50°C, while the best conditions of microwave pretreatment were 50p for 5 minutes. The enzymatic saccharification of sugarcane bagasse showed a maximum yield of reducing sugars when the sugarcane bagasse was pretreated with hydrogen peroxide, obtaining 0.41 g/g. Finally, the maximum ethanol concentration (4.32 g/L) was obtained after 48 hours of fermentation with commercial <em>Saccharomyces cerevisae</em>. <strong>Implications.</strong> The sugar agroindustry in Mexico is limited to the production of sucrose and ethanol, being necessary a sustainable productive diversification. <strong>Conclusions.</strong> The isolation of autochthonous fungal strains allowed the production of cellulases and xylanases by solid fermentation with adequate specificity to hydrolyze/saccharify pretreated sugarcane bagasse and its subsequent conversion to ethanol.</p>

Optimization Conditions for Ethanol Production from Sweet Sorghum Juice by Thermotolerant Yeast Saccharomyces cerevisiae: Using a Statistical Experimental Design

The optimum fermentation conditions for ethanol production from sweet sorghum juice (SSJ) by the thermotolerant yeast Saccharomyces cerevisiae DBKKUY-53 were determined using a statistical experimental design. Based on the Plackett–Burman design (PBD), yeast cell concentration, sugar concentration, and yeast extract were the significant independent fermentation factors affecting the ethanol production from SSJ at 37 °C by S. cerevisiae DBKKUY-53. These significant factors were optimized using response surface methodology (RSM) based on a central composite design (CCD). The result revealed that the optimum conditions for ethanol fermentation were 7.85 × 107 cells/mL yeast cell concentration, 247 g/L sugar concentration, and 9.99 g/L yeast extract. Verification of the ethanol production using the optimum conditions revealed that the maximum ethanol concentration of 99.75 g/L and the productivity of 2.77 g/L/h were achieved. When the ethanol production was carried out in a 2 L fermentor under optimum conditions, the ethanol concentration was 101.81 g/L and the productivity was 2.83 g/L/h. This finding suggested that the thermotolerant yeast S. cerevisiae DBKKUY-53 has excellent potential for commercial ethanol production at high temperatures.

Dehydration of Aqueous Ethanol Mixtures By Extractive Distillation

This paper investigate the dehydration of ethanol by extractive distillation process with salt in solvent and also without salt. There are many sources to produce ethanol. It can be obtained from plants and agricultural wastes as well as olefins from cracking units of petroleum refining. Because the methods of ethanol production are the hydration method and fermentation, water molecules are present in ethanol. It has to be dehydrated to use as a fuel in automobile engines and other applications. There are many methods to separate water from ethanol to improved concentration. In this paper, the dehydration of ethanol is carried out by extractive distillation process and use ethylene glycol as a separating agent with calcium chloride as salt in order to improve the concentration of ethanol. Different ratios of ethanol-water and ethylene glycol such as (1:1:0, 1:1:0.25, 1:1:0.25 (20% of solvent)) were tested to obtain the best result of concentration percent. The maximum ethanol concentration was 92 vol% which obtained from 52 vol% ethanol in feed mixture.

Comparative evaluation of bioethanol fermentation process parameters using RSM, ANN and ANFIS

AbstractThe drive for renewable energy as an alternative to fossil fuel is on the increase globally. Modeling a renewable energy process is crucial for increasing process monitoring and control of plant efficiency for the ultimate objective of optimal biorefinery operations. This study aims to develop and compare models that best predict the fermentation process parameters of bioethanol production using corn‐steep liquor (CSL) as a media supplement. The response surface method (RSM), artificial neural networks (ANNs) and adaptive neuro‐fuzzy inference system (ANFIS) were tested in the modeling of bioethanol fermentation processes. Box–Behnken design was used to investigate fermentation process parameters considering the effect of CSL (0.5–5.5 w/v), pH (4, 5), time (12–36 h), temperature (25–35°C) and inoculum size (0.5–5.5 v/v). The results from the kinetics study show media formulation with corn steep liquor results in a comparable yield with that substituted with yeast extract. The study shows that, for CSL, a maximum ethanol concentration of 17.40 g L−1 was obtained after 48 h of fermentation while 21.53 g L−1 was attained after 6 h for the media formulation with yeast extract. Based on the model evaluation using statistical error indices, ANN predictability was better at R2 = 0.90; R = 0.95; SEP = 1.73. The ANN models described the process better than ANFIS and RSM. This study shows the intelligent predictive ability of ANN that could be useful for the scale‐up process of ethanol production in industry. © 2023 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Enhance the Growth of <i>Clostridium ljungdahlii</i> Microbial Cells by Modifying the Medium Composition and Trace Metals

Syngas fermentation is an alternative route that combines the advantages of thermochemical and biochemical processes have been proposed for biomass conversion to ethanol. One of the main obstacles to syngas fermentation is the low yield of ethanol, caused by the limited utilization of the syngas substrate due to low microbial cell concentration in the fermentation system. This research examined the modification of fermentation medium to improve microbial cell growth. The modifications were to increase the concentration of micronutrients/trace metals and macronutrients in the medium. The results showed that the maximum mass cell and maximum growth rate produced by microbial growth in the modified trace metal medium were 0.63 g/L and 0.0076 h-1, while in a modified macronutrient medium were 0.97 g/L and 0.0298 h-1. Modification of the macronutrient medium was able to increase the yield of biomass, but the opposite occurred in the modification of the trace metals. Meanwhile, the maximum concentration of ethanol from syngas fermentation in the modified macronutrient medium was lower than the concentration of ethanol in the standard medium.