Bioethanol Fermentation Process Research Articles

A Study on the Potential of Valorizing Sargassum latifolium into Biofuels and Sustainable Value-Added Products.

To increase the limited commercial utility and lessen the negative environmental effects of the massive growth of brown macroalgae, this work illustrates the feasibility of valorizing the invasively proliferated Sargassum latifolium into different value-added products. The proximate analysis recommends its applicability as a solid biofuel with a sufficient calorific value (14.82 ± 0.5 MJ/kg). It contains 6.00 ± 0.07% N + P2O5 + K2O and 29.61 ± 0.05% organic C. Its nutritional analysis proved notable carbohydrate, ash, protein, and fiber contents with a rational amount of lipid and a considerable amount of beneficial macronutrients and micronutrients, with a low concentration of undesirable heavy metals. That recommends its application in the organic fertilizer, food, medicine, and animal fodder industries. A proposed eco-friendly sequential integrated process valorized its biomass into 77.6 ± 0.5 mg/g chlorophyll, 180 ± 0.5 mg/g carotenoids, 5.86 ± 0.5 mg/g fucoxanthin, 0.93 ± 0.5 mg/g β-carotene, 21.97 ± 0.5% (w/w) alginate, and 16.40 ± 0.5% (w/w) cellulose, with different industrial and bioprocess applications. Furthermore, Aspergillus galapagensis SBWF1, Mucor hiemalis SBWF2, and Penicillium oxalicum SBWF3 (GenBank accession numbers OR636487, OR636488, and OR636489) have been isolated from its fresh biomass. Those showed wide versatility for hydrolyzing and saccharifying its polysaccharides. A Gram-negative Stutzerimonas stutzeri SBB1(GenBank accession number OR764547) has also been isolated with good capabilities to ferment the produced pentoses, hexoses, and mannitol from the fungal saccharification, yielding 0.25 ± 0.014, 0.26 ± 0.018, and 0.37 ± 0.020 g ethanol/g algal biomass, respectively. Furthermore, in a pioneering step for valuing the suggested sequential biomass hydrolysis and bioethanol fermentation processes, the spent waste S. latifolium disposed of from the saccharification process has been valorized into C-dots with potent biocidal activity against pathogenic microorganisms.

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.

Immobilization of Saccharomyces cerevisiae in Jackfruit (Artocarpus heterophyllus) Seed Fiber for Bioethanol Production

Bioethanol is alternative renewable energy typically obtained from glucose through a fermentation process using Saccharomyces cerevisiae. In the bioethanol fermentation process using yeast, there are several inhibiting factors, such as a high concentration of substrate, ethanol as the product, and nutrients. The present study aimed to investigate the effect of fermentation time (12- 72 hours), immobilized carrier size (sizes of 0.5 cm3 , 1 cm3 , and 1.5 cm3 ), and medium pH (3.0, 4.0, and 5.0) on the ethanol fermentation process using immobilized yeast in jackfruit (Artocarpus heterophyllus) seeds and subsequently to compare its performance with a free cell system. The highest ethanol concentration (89.15 g/L) with a yield of 96.92% was obtained by immobilizing yeast in jackfruit seed at a fermentation time of 72 hours, carrier size of 0.5 cm3 , and medium pH of 5.0. When compared to the free cell system fermentation under identical operating conditions, immobilized yeast in jackfruit seed obtained 1.41 times higher ethanol concentration. Jackfruit seed also led to a higher ethanol concentration compared to other S. cerevisiae carriers. Altogether, our findings imply that jackfruit seed has great potential as a carrier of S. cerevisiae in the process of fermenting glucose into ethanol

Technoeconomic Analysis of Integrated Bioethanol from Elephant Grass (Pennisetum purpureum) with Utilization of Its Residue and Lignin

Bioethanol has been developed as an alternative biofuel. Elephant grass is one of the lignocelluloses that can be used as a source of bioethanol. The bioethanol fermentation process should be improved along with its economic competitiveness to promote its wider application. This study aims to investigate and to evaluate the best scheme of biethanol (standalone) and the combination of bioethanol and its by-products through technoeconomic analysis. The method used is collecting data from several previous studies and simulating it with SuperPro Designer. Data from flowsheeting simulation is used as economic simulation data using Microsoft Excel. The results of this study indicate that the processing of biogas and lignin waste as fuel and lignosulfonates can increase the economic value of the bioethanol production process. The best economic value is the bioethanol production process using biogas and lignin as fuel for a Biomass Power Plant which is called Pembangkit Listrik Tenaga Biomassa (PLTBm) with a Net Present Value (NPV) of IDR 364,358,976,036, Internal Rate of Return (IRR) 11.32%, Pay Back Period (PBP) 7.2 years, and Profitability Index (PI) 1.08

Pilot scale demonstration of a two-stage pretreatment and bioethanol fermentation process for cotton gin trash

A two-stage dilute acid and steam explosion (SE) pretreatment process was developed and evaluated at pilot scale for ethanol production from cotton gin trash (CGT). Optimal conditions for CGT processing were defined as 1:6 solids to liquids ratio with 9% H2SO4 wt. on solids at 180 °C for 15 min. during stage 1 with ensuing pressed fibres successively exposed to SE at 200 °C for 5 min during stage 2. SE fibres were highly acquiescent to enzyme hydrolysis (76%) in the presence of PEG 6000, yielding 381 g glucose kg−1 fibre. Simultaneous saccharification and fermentation (SSF) trials validated the selected process option and additional fed-batch SSFs confirmed titres above the minimum 4% ww-1 benchmark for economically viable distillation. The practicality of converting CGT to ethanol was demonstrated at pilot scale with titres above 4% ww-1 and a conversion efficiency of 60% t−1 dry GCT.

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility.

Environmental management and valorization of cultivated tobacco stalks by combined pretreatment for potential bioethanol production

Expanding concern over exhausting fossil fuel and nursery gas limits must lead the more intrigued in renewable fuel-making from biomass sources counting sugars, starches, and lignocellulosic materials. Cultivated tobacco stalk is one of the massive amounts of available biorefinery wastes. Therefore, tobacco stalk was used for bioethanol production in this study. It contains abundant chemical compounds including cellulose, hemicellulose, and lignin 35.45 ± 0.13(%), 43.90 ± 0.26 (%), and 18.16 ± 0.28 (%), respectively. The total and reducing sugar utilizing phenol-sulfuric and DNS methods were carried out before and after the bioethanol fermentation process. Also, the combined pretreatment process was used for the degradation of the biomass and better accessibility to available sugars to increase the bioethanol production. Hydrolysate with the highest sugar concentration was selected and proceeded to bioethanol fermentation for 72 h. From the experimental results obtained, the total and reducing sugar concentration of tobacco stalk was 27.97 g/L and 5.43 g/L, individually. The results revealed the highest ethanol yields 75.74 (g/L) was reached at 48 h fermentation. Consequently, this form of combined pretreatment technique is a promising method of increasing the overall yield in the dried tobacco stalks to the bioethanol production process.

Properties Activity of Yeast Against Seaweed Bioethanol Fermentation Time and Its Functional Group

The activity of yeast in relationship with fermentation time of seaweed bioethanol and functional groups formed. The bioethanol fermentation process begins with the liquification process which is the cooking stage with the addition of water as much as 50 times the weight of seaweed, cooked until it boils. Saccharification is the step of adding bean sprouts to seaweed filtrate at a temperature ± 90°C. For the breakdown of polysaccharides into glucose. Fermentation, carried out at a temperature ± 30°C, by adding about 0.02% yeast. Furthermore, anaerobic fermented for second days; thirth days; fourth days; fifth days and sixth days. The bioethanol obtained were then analyzed with spectroscopic IR. The results showed that the functional group formed was –OH in absorption 3600 – 3200 cm−1. Reinforced of absorption C – O, 1200 – 1000 cm−1, shows the presence of the alcohol compound, consist of tertiary alcohol and secondary alcohol. Primary alcohol, only appears on 2nd day and 4th day. Thus it can be said that the activity of yeast (Saccharomyces cerevisiae) can break the primary alcohol bond on 3rd day and up.

Quantitative Structure-Toxicity Relationship analysis of combined toxic effects of lignocellulose-derived inhibitors on bioethanol production

This study performed a Quantitative Structure-Toxicity Relationship (QSTR) model to evaluate the combined toxicity of lignocellulose-derived inhibitors on bioethanol production. Compared with all the control groups, the combined systems exhibited lower conductivity values, higher oxidation-reduction potential values, as well as maximum inhibition rates. These results indicated that the presence of combined inhibitors had a negative effect on the bioethanol fermentation process. Meanwhile, QSTR model was excellent for evaluating the combined toxic effects at lower ferulic acid concentration (([1:4] × IC50)) and (([1:1] × IC50)), due to higher R2 values (0.994 and 0.762), lower P values (0.000 and 0.023) and relative error values (less than 30%). The obtained results also showed that the combined toxic effects of ferulic acid and representative lignocellulose-derived inhibitors were relevant to different molecular descriptors. Meanwhile, the interactions of combined inhibitors were weaker when ferulic acid was at low concentration ([1:4] × IC50).

The Effect of Steam and Glycerol Pretreatment on Chemical Contents of Oil Palm Empty Fruit Bunch (EFB)

This research aimed to evaluate the effect of the type of solvent, pH, substrate loading, and reaction time on the chemical components of palm empty fruit bunches (EFB). Steam pretreatment was set up at a temperature of 121 °C and pressure of 1.18 bar, using an autoclave with substrate loading of 5, 10, 15 and 20 % w/v at reaction times of 15 and 60 min. Distilled water, waste glycerol, alkaline glycerol and acidic glycerol were compared as solvents during steam pretreatment. The results showed that with distilled water, better pretreatment was achieved at 5 % and 10 % loading for 60 min. During the pretreatment with waste glycerol at 5 % loading an increase on the reaction time from 15 to 60 min reaction resulted in a remarkable increase in reducing sugar in the liquid phase. Overall, the best steam pretreatment conditions were observed using alkaline glycerol at 5 % w/v and 15 min reaction time, resulting in holocellulose (cellulose plus hemicellulose) increase to 87.98 % and a lignin decrease to 9.17 %. However, pretreatment with glycerol for 15 min was better than those for 60 min using either glycerol or distilled water. The results suggest that waste glycerol during steam pretreatment of EFB can be utilized effectively at short reaction times and at an increased pH to achieve a high output of cellulose and hemicellulose for sugar conversion in the bioethanol fermentation process.

Batch bioethanol production via the biological and chemical saccharification of some Egyptian marine macroalgae.

Marine seaweeds (macroalgae) cause an eutrophication problem and affects the touristic activities. The success of the production of the third-generation bioethanol from marine macroalgae depends mainly on the development of an ecofriendly and eco-feasible pretreatment (i.e. hydrolysis) technique, a highly effective saccharification step and finally an efficient bioethanol fermentation step. Therefore, this study aimed to investigate the potentiality of different marine macroalgal strains, collected from Egyptian coasts, for bioethanol production via different saccharification processes. Different marine macroalgal strains, red Jania rubens, green Ulva lactuca and brown Sargassum latifolium, have been collected from Egyptian Mediterranean and Red Sea shores. Different hydrolysis processes were evaluated to maximize the extraction of fermentable sugars; thermochemical hydrolysis with diluted acids (HCl and H2 SO4 ) and base (NaOH), hydrothermal hydrolysis followed by saccharification with different fungal strains and finally, thermochemical hydrolysis with diluted HCl, followed by fungal saccharification. The hydrothermal hydrolysis of S. latifolium followed by biological saccharification using Trichoderma asperellum RM1 produced maximum total sugars of 510mgg-1 macroalgal biomass. The integration of the hydrothermal and fungal hydrolyses of the macroalgal biomass with a separate batch fermentation of the produced sugars using two Saccharomyces cerevisiae strains, produced approximately 0·29g bioethanolg-1 total reducing sugars. A simulated regression modelling for the batch bioethanol fermentation was also performed. This study supported the possibility of using seaweeds as a renewable source of bioethanol throughout a suggested integration of macroalgal biomass hydrothermal and fungal hydrolyses with a separate batch bioethanol fermentation process of the produced sugars. The usage of marine macroalgae (i.e. seaweeds) as feedstock for bioethanol; an alternative and/or complimentary to petro-fuel, would act as triple fact solution; bioremediation process for ecosystem, renewable energy source and economy savings.

Comparison of Ozonation and Evaporation as Treatment Methods of Recycled Water for Bioethanol Fermentation Process

The paper compared the performance of the ethanol yield after alcoholic fermentation with samples of rejected (RW) and permeate water (PW), RW and PW treated by oxidation with ozone (O3) (5 and 15 min) and evaporation, aiming the recirculation back to the bioethanol process. RW and PW were collected after an anaerobic bioreactor (AnBR) used for stillage treatment. Nine types of fermentations were made, where one used 100% tap water (control) and the remaining used 80% of recycled water and 20% of tap water. Comparing with the control (15.68%), evaporated permeate water and permeate water oxidized for 15 min achieved the highest and closest ethanol concentrations in v/v with 14.68 and 14.08% respectively. RW and PW had the lowest ethanol results with 8.43 and 8.68%. The studied methods for water treatment are effective to recycle water taking into consideration the ethanol yield, allowing a good possibility of recirculation. Chemical oxygen demand, ammonia nitrogen and phosphate content did not strongly affect the ethanol yield in all samples treated, with similar results. Oxidation was more environmental friendly and cheaper if performed in 5 min. Further research in the monitoring of the fermentation, ethanol quality and in the number of cycles of fermentation with recycled water is needed.

Indentation with atomic force microscope, Saccharomyces cerevisiae cell gains elasticity under ethanol stress

During bioethanol fermentation process, Saccharomyces cerevisiae cell membrane is the first target to be attacked by the accumulated ethanol. In such a prominent position, S. cerevisiae cell membrane could reversely provide protection through changing fluidity or elasticity secondary to remodeled membrane components or structure during the fermentation process. However, there is yet to be a direct observation of the real effect of the membrane compositional change. In this study, atomic force microscope-based strategy was performed to determine Young's modulus of S. cerevisiae to directly clarify ethanol stress-associated changes and roles of S. cerevisiae cell membrane fluidity and elasticity. Cell survival rate decreased while the cell swelling rate and membrane permeability increased as ethanol concentration increased from 0% to 20% v/v. Young's modulus decreased continuously from 3.76MPa to 1.53MPa while ethanol stress increased from 0% to 20% v/v, indicating that ethanol stress induced the S. cerevisiae membrane fluidity and elasticity changes. Combined with the fact that membrane composition varies under ethanol stress, to some extent, this could be considered as a forced defensive act to the ethanol stress by S. cerevisiae cells. On the other hand, the ethanol stress induced loosening of cell membrane also caused S. cerevisiae cell to proactively remodel membrane to make cell membrane more agreeable to the increase of environmental threat. Increased ethanol stress made S. cerevisiae cell membrane more fluidized and elastic, and eventually further facilitated yeast cell’s survival.

Response surface methodology for optimization of solvent extraction to recovery of acetic acid from black liquor derived from Typha latifolia pulping process

Most modern commodity chemicals are synthesized from fossil resources. Organic acids are attractive targets in process development for the emerging renewable resources based biorefinery industry. Liquid-liquid extraction (LLE) is a common separation method for the recovery of a solute from a solution and can be applied to the recovery of acetic acid from the black liquor of Typha latifolia pulp prior to the bioethanol fermentation process. LLE of acetic acid was studied using alkanes containing 37% (w/w) concentrations of trioctylphosphine oxide. The extraction yield has also been evaluated with a four-level factorial design. Four independent variables, pH (1–3), temperature (25–65°C), residence time (24–48min), and concentrated hydrolyzates (1–10 times), were screened. The results showed that a lower pH and temperature gave the highest yield for the extraction of the organic acid. The yield also increased with less concentrated hydrolyzates. However, the residence time did not affect the yield. The maximum extraction yield of acetic acid achieved 71.7% at pH 1.02, 31.4°C, 46.8min, and 1.07 times. And the maximum extraction yield of formic acid and lactic acid was 75.1% (obtained at pH 1.46, 25.0°C, 44.5min, and 1.04 times) and 65.0% (obtained at pH 1.71, 35.9°C, 44.6min, and 1.11 times), respectively. It appears that the stabilities of the extracted acids are highly affected by the initial feed concentration of the organic acid.

The effect of dilute acid pre-treatment process in bioethanol production from durian (Durio zibethinus) seeds waste

Lignocellulosic biomass is one of the promising feedstocks for bioethanol production. The process starts from pre-treatment, hydrolysis, fermentation, distillation and finally obtaining the final product, ethanol. The efficiency of enzymatic hydrolysis of cellulosic biomass depends heavily on the effectiveness of the pre-treatment step which main function is to break the lignin structure of the biomass. This work aims to investigate the effects of dilute acid pre-treatment on the enzymatic hydrolysis of durian seeds waste to glucose and the subsequent bioethanol fermentation process. The yield of glucose from dilute acid pre-treated sample using 0.6% H2SO4 and 5% substrate concentration shows significant value of 23.4951 g/L. Combination of dilute acid pre-treatment and enzymatic hydrolysis using 150U of enzyme able to yield 50.0944 g/L of glucose content higher compared to normal pre-treated sample of 8.1093 g/L. Dilute acid pre-treatment sample also shows stable and efficient yeast activity during fermentation process with lowest glucose content at 2.9636 g/L compared to 14.7583g/L for normal pre-treated sample. Based on the result, it can be concluded that dilute acid pre-treatment increase the yield of ethanol from bioethanol production process.

Intracellular metabolic changes in Saccharomyces cerevisiae and promotion of ethanol tolerance during the bioethanol fermentation process

During the batch bioethanol fermentation process, although Saccharomyces cerevisiae cells are challenged by accumulated ethanol, our previous work showed that the ethanol tolerance of S. cerevisiae increased as fermentation time increased.

Changes of Saccharomyces cerevisiae cell membrane components and promotion to ethanol tolerance during the bioethanol fermentation

During bioethanol fermentation process, Saccharomyces cerevisiae cell membrane might provide main protection to tolerate accumulated ethanol, and S. cerevisiae cells might also remodel their membrane compositions or structure to try to adapt to or tolerate the ethanol stress. However, the exact changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation still remains poorly understood. This study was performed to clarify changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation. Both cell diameter and membrane integrity decreased as fermentation time lasting. Moreover, compared with cells at lag phase, cells at exponential and stationary phases had higher contents of ergosterol and oleic acid (C18:1) but lower levels of hexadecanoic (C16:0) and palmitelaidic (C16:1) acids. Contents of most detected phospholipids presented an increase tendency during fermentation process. Increased contents of oleic acid and phospholipids containing unsaturated fatty acids might indicate enhanced cell membrane fluidity. Compared with cells at lag phase, cells at exponential and stationary phases had higher expressions of ACC1 and HFA1. However, OLE1 expression underwent an evident increase at exponential phase but a decrease at following stationary phase. These results indicated that during bioethanol fermentation process, yeast cells remodeled membrane and more changeable cell membrane contributed to acquiring higher ethanol tolerance of S. cerevisiae cells. These results highlighted our knowledge about relationship between the variation of cell membrane structure and compositions and ethanol tolerance, and would contribute to a better understanding of bioethanol fermentation process and construction of industrial ethanologenic strains with higher ethanol tolerance.

Control of Bioethanol Fermentation Process: NARX-Based MPC (NARX-MPC) versus Linear-Based MPC (LMPC)

Control of Bioethanol Fermentation Process: NARX-Based MPC (NARX-MPC) versus Linear-Based MPC (LMPC)

An integrated process for continuous cellulosic bioethanol production

A high-efficiency, integrated bioethanol production process was developed in this study, using Miscanthus as lignocellulosic biomass. The continuous process involved a twin-screw extruder, a pretreated biomass washing/dewatering process, and a saccharification/fermentation process. In addition, the integration process was designed for the reuse of pretreatment solution and the production of highly concentrated bioethanol. Pretreatment was performed with 0.72 M NaOH solution at 95 °C using an 80 rpm twin-screw speed and a flow rate of 90mL/min (18 g/min of raw biomass feeding). Following washing and dewatering steps, the pretreated biomass was subjected to simultaneous saccharification and bioethanol fermentation processes. The maximum ethanol concentration, yield from biomass, and total volume obtained were 59.3 g/L, 89.9%, and 60 L, respectively, using a pretreated biomass loading of 23.1% (w/v) and an enzyme dosage of 30 FPU/g cellulose. The results presented here constitute an important contribution toward the production of bioethanol from Miscanthus.

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

In the last decades the increasing energy requirements along with the need to face the consequences of climate change have driven the search for renewable energy sources, in order to replace as much as possible the use of fossil fuels. In this context biomass has generated great interest as it can be converted into energy via several routes, including fermentation and anaerobic digestion. The former is the most common option to produce ethanol, which has been recognized as one of the leading candidates to substitute a large fraction of the liquid fuels produced from oil. As the economic competitiveness of bioethanol fermentation processes has to be enhanced in order to promote its wider implementation, the most recent trends are directed towards the use of fermentation by-products within anaerobic digestion. The integration of both fermentation and anaerobic digestion, in a biorefinery concept, would allow the production of ethanol along with that of biogas, which can be used to produce heat and electricity, thus improving the overall energy balance. This work aims at reviewing the main studies on the combination of both bioethanol and biogas production processes, in order to highlight the strength and weakness of the integrated treatment for industrial application.