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This review explores circular economy principles in regard to ethanol production from paper-mill sludge. Environmental sustainability and renewability over fossil fuels make second generation ethanol an attractive energy source in a rapidly growing population and consumption world. Paper sludge (PS), a by-product of the pulp and paper (P&P) industry, can no longer be recycled for paper production and is mainly disposed of in landfills. Therefore, it poses a major environmental challenge. However, it has shown potential as a valuable raw material for ethanol production, along with other pulp and paper products, due to its abundant availability and high cellulosic content. This waste-to-energy (WtE) technology for ethanol production is proposed as an alternative, aligning with circular economy concepts to maximize resource efficiency and minimize waste. This review underlines the circular economy aspects of bioethanol production within paper mill sludge management systems. Circular economy principles applied to ethanol production from PS offer a promising avenue for sustainable biofuel development that not only addresses waste management challenges but also enhances the overall environmental performance of biofuel production. Furthermore, economic benefits are described, highlighting the potential for job creation and community development. [ABSTRACT FROM AUTHOR]

This review explores circular economy principles in regard to ethanol production from paper-mill sludge. Environmental sustainability and renewability over fossil fuels make second generation ethanol an attractive energy source in a rapidly growing population and consumption world. Paper sludge (PS), a by-product of the pulp and paper (P&P) industry, can no longer be recycled for paper production and is mainly disposed of in landfills. Therefore, it poses a major environmental challenge. However, it has shown potential as a valuable raw material for ethanol production, along with other pulp and paper products, due to its abundant availability and high cellulosic content. This waste-to-energy (WtE) technology for ethanol production is proposed as an alternative, aligning with circular economy concepts to maximize resource efficiency and minimize waste. This review underlines the circular economy aspects of bioethanol production within paper mill sludge management systems. Circular economy principles applied to ethanol production from PS offer a promising avenue for sustainable biofuel development that not only addresses waste management challenges but also enhances the overall environmental performance of biofuel production. Furthermore, economic benefits are described, highlighting the potential for job creation and community development.

Biofuels are the cheapest source of energy, and the continuous decline of traditional sources of energy with the increasing population leads to looking for alternatives to reduce the consumption of traditional sources of energy. Bioethanol production from lignocellulosic wastes and cellulosic wastes is not a new approach for fuel production but a cheap and accessible way for the production of fuel. Bacillus is one of the major species that can act as a source of diversified enzymes. In this study, it was emphasized on screening and isolation of a novel, characterization, and best catalytic action on both celluloses and proteins in the presence of different carbon and nitrogen sources. It was observed the effective catalytic breakdown of cellulose with the crude enzyme to glucose allowed fur for fermentation with Saccharomyces, ultimately leading to the generation of alcohol. The study aims to isolate the microbes that can produce cellulases and enzymes and could be used for biodegradation to produce ethanol in the reaction. The maximum enzyme activity was achieved at 3.112 UI with optimized pH and temperature, and the maximum conversion of sugars into alcohol was about 70% in the newspaper, cartons, colored paper, and disposable paper cups. An essential observation was the decolorization of the origami craft paper within 24 hours. The study was involved in enhancing the maximum Enzyme activity of cellulases from different cellulosic raw materials. Hence, it was achieved by JCB strain, optimization of pH, temperature, and acids for the biodegradation. The presence of peaks at 3200 and 2900 was a confirmation of ethanol bonds in the biodegradation reaction mixtures. [ABSTRACT FROM AUTHOR]

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The extensive growth of energy and plastic demand has raised concerns over the depletion of fossil fuels. Moreover, the environmental conundrums worldwide integrated with global warming and improper plastic waste management have led to the development of sustainable and environmentally friendly biofuel (bioethanol) and biopolymer (lactic acid, LA) derived from biomass for fossil fuels replacement and biodegradable plastic production, respectively. However, the high production cost of bioethanol and LA had limited its industrial-scale production. This paper has comprehensively reviewed the potential and development of third-generation feedstock for bioethanol and LA production, including significant technological barriers to be overcome for potential commercialization purposes. Then, an insight into the state-of-the-art hydrolysis and fermentation technologies using macroalgae as feedstock is also deliberated in detail. Lastly, the sustainability aspect and perspective of macroalgae biomass are evaluated economically and environmentally using a developed cascading system associated with techno-economic analysis and life cycle assessment, which represent the highlights of this review paper. Furthermore, this review provides a conceivable picture of macroalgae-based bioethanol and lactic acid biorefinery and future research directions that can be served as an important guideline for scientists, policymakers, and industrial players. [ABSTRACT FROM AUTHOR]

The enormous capability of microalgae for biomass production and co-products has recently been widely researched from a range of research approaches. Microalgae biomass has been discovered as a suitable feedstock for biofuel generation in the third generation. Although they may easily be cultivated in the laboratory, commercial cultivation involves several important considerations, including design, expense, contamination risk, and hygiene. This paper reviews some conventional microalgal cultivation methods along with some harvesting techniques. A short note on the disadvantages of conventional microalgal biofilm cultivation and the need for advanced cultivation techniques are also listed. Further, it highlights some of the modern techniques used for the cultivation of biofilm-based microalgae. It also gives brief information on the various factors affecting the formation of microalgal biofilm. A detailed description of the application of microalgal biofilm concerning biofuel generation is also reviewed. [ABSTRACT FROM AUTHOR]

This review paper examines acid and alkaline pretreatments on perennial grasses for second-generation (2G) bioethanol production, a relatively unexplored area in this field. It compares the efficiency of these pretreatments in producing fermentable sugar and bioethanol yield. This study finds that alkaline pretreatment is more effective than acidic pretreatment in removing lignin and increasing sugar yield, leading to higher ethanol yields. However, it is costlier and requires longer reaction times than acidic pretreatment, while acidic pretreatment often leads to the formation of inhibitory compounds at higher temperatures, which is undesirable. The economic and environmental impacts of lignocellulosic biomass (LCB) are also assessed. It is revealed that LCB has a lower carbon but higher water footprint and significant costs due to pretreatment compared to first-generation biofuels. This review further explores artificial intelligence (AI) and advanced technologies in optimizing bioethanol production and identified the gap in literature regarding their application to pretreatment of perennial grasses. This review concludes that although perennial grasses hold promise for 2G bioethanol, the high costs and environmental challenges associated with LCB necessitate further research. This research should focus on integrating AI to optimize the pretreatment of LCB, thereby improving efficiency and sustainability in 2G biofuel production. [ABSTRACT FROM AUTHOR]

Bioethanol, as a renewable energy source, has been widely used in the energy sector, particularly in replacing traditional petroleum energy, and holds great potential. This study involves a whole life cycle assessment of bioethanol production and the co-production of high-value by-products—xylose, lignin, and steam—using three types of waste biomass: corn cobs, corn straw, and wheat straw as feedstocks by chopping, pretreatment, hydrolysis, fermentation, and distillation methods. Secondly, the benefits of three raw materials are compared for preparing bioethanol, and their impact on the environment and energy production is analyzed. The comparison indicates that corn cobs offer the best overall benefits, with a net energy balance (NEB) of 6902 MJ/Mg of ethanol and a net energy ratio (NER) of 1.30. The global warming potential (GWP) is 1.75 × 10−2, acidification potential (AP) is 1.02 × 10−2, eutrophication potential (EP) is 2.63 × 10−4, photochemical ozone creation potential (POCP) is 3.19 × 10−8, and human toxicity potential (HTP) is 1.52 × 10−4. This paper can provide a theoretical reference and data supporting the green refining of bioethanol and the high-value utilization of by-products, and broaden its application prospects. [ABSTRACT FROM AUTHOR]

From year to year, mankind is struggling with an increasing climate crisis. Constant climate change is related to human activities. The global dependence on non-renewable fossil fuels to meet our current energy needs cannot be sustained longer in the face of depleting fuel reserves. Particular attention should be paid to biofuels produced from lignocellulosic biomass, which is a waste product from the forestry, paper and agricultural industries, or a product derived from energy crops, intended for biofuel purposes. A problem that arises when using lignocellulosic biomass is the limited availability of fermentable sugars due to its complicated structure. For this reason, various methods of pretreatment of the raw material are used. The aim of the pretreatment is to increase the availability of cellulose for hydrolytic enzymes and to separate the main fractions of the lignocellulosic material, mainly the lignin molecule. After pretreatment and hydrolysis, the monomeric sugars are further processed into ethanol through the fermentation process. The last stages in biotechnological lignocellulose conversion are the distillation and dehydration process to obtain pure biofuel. This work is a review of the literature on second-generation biofuels produced from lignocellulosic biomass. Issues ranging from various types of raw materials, methods of its pretreatment, enzymatic hydrolysis, fermentation with the participation of various microorganisms, to various methods of dehydration of the obtained bioethanol were discussed. [ABSTRACT FROM AUTHOR]

In order to improve the process feasibility and cost function of bioethanol production, higher titres of biomass saccharifying cellulases need to be produced on commercial scale. Diverse lignocellulosic substrates including abundantly accessible paddy straw can be utilized as carbonaceous substrates for the production of cellulose hydrolysing enzymes. This study aims to meliorate milled and sequential acid/alkali pre-treated paddy straw as inducer-substrates for the synthesis of fungal secretomes from Penicillium mallochii repertoires under solid state and liquid shake flask fermentation (SSF and LSF, respectively). The analysis of enzymatic activities of the respective secretomes reinforced the cellulolytic potential of P. mallochii where the maximum cellulase production (Filter paper cellulase: 76.43, Carboxymethyl cellulase: 130.29, Avicelase: 18.6 and β-glucosidase: 83.59 U L−1) was exhibited under LSF conditions using pre-treated paddy straw as the inducer. The disorganisation of the cellulosic structure via hydrogen bond disruption, as indicated by FTIR analysis, after acid/alkali pretreatment allowed a better establishment of fungus on the substrate, thereby facilitating higher cellulase production. A maximum ethanol content of 11.63 g L−1 was obtained at 48 h of simultaneous saccharification and fermentation using pre-hydrolysed paddy straw at 10% (w/v) solid loading and a cellulase dosage of 25 FPU gds−1. These results affirm the utilization of paddy straw for cellulase and ethanol production in an integrated bioprocess that can further be explored and optimized for scale-up studies to cater industrial applications. [ABSTRACT FROM AUTHOR]

The increasing population and industrialization have increased the day-to-day demand for energy. Global warming and other climatic disasters caused by to burning of conventional fossil fuels have laid the need for an alternative and renewable fuel. Concurrently, the worldwide demand and production of bio-ethanol, a bio-based sustainable fuel, is increasing continuously. Fungal saccharification of lignocellulosic biomass takes place simultaneously with the secretion of various metabolites, which function as a catalytic system to liberate soluble sugars from insoluble composite biomass. Cellulase holds a major role in converting lignocellulosic feedstock into fermentable sugar. Fungi, especially filamentous fungi, preferably the Aspergillus species, are known to produce cellulase. Amongst the lignocellulosic biomass, rice straw is considered as one of the most attractive materials for producing bioethanol because of its high cellulosic and hemicellulosic content, which can be hydrolyzed into fermentable sugars. However, the recalcitrant nature of the substrate imposes considerable challenges and limitations to bioethanol production. To combat these challenges, various pretreatment techniques such as chemical, physical and physico-chemical processes are known to be effective enough to enhance the efficiency of enzymatic saccharification in order to make the complete process economically feasible. The present work deals with the isolation and selection of hypercellulase-producing fungal species. These species were used along with the pretreatment techniques either alone or in combination for efficient hydrolysis of rice straw to obtain the maximum amount of the released sugar. [ABSTRACT FROM AUTHOR]

Sweet sorghum is a cereal crop that can potentially serve as a source for bioethanol production. This study aims to analyse the genetic diversity of promising genotypes of sweet sorghum at the molecular level. The genetic material consisted of 12 sweet sorghum genotypes. The genetic diversity estimated using 59 SSRs markers showed a polymorphism value of 0.48 and the coefficient of genetic diversity was classified as moderate. The unweighted pair group method arithmetic average (UPGMA) analysis assigned the tested genotypes into three major clusters with a similarity coefficient level of 0.596. This indicates that the genetic similarity of the tested genotypes is moderate to high. Eight unique loci were identified with the SSRs markers in six genotypes, which are considered to control high sugar traits. [ABSTRACT FROM AUTHOR]

Water Hyacinth (Eichhornia crassipes) is a weedy lignocellulosic material which represents the best substrate for the production of bioethanol in tropical countries due to its more availability and more biomass yield. For the fermentation and bioethanol production from water hyacinth, the different bacterial and fungal inoculants were used. Water hyacinth was obtained from ukkadam-valankulam lake, Coimbatore. These leaves were washed properly to remove soil and contaminants and dried for 3 hours at 120 ℃. It was grained into a fine powder and sieved using 1.5 μm in diameter nylon sieve. The sieved material was cultured using different microbial culture such as Aspergillus oryzae, Aspergillus niger and Saccharomyces cerevisiae. After 21 days incubation, the culture was distilled using rotary vacuum evaporator and the produced bioethanol was analyzed by Fourier-transform infrared spectroscopy (FTIR) technique. The previous report showed, less yield only obtained using water hyacinth, potato peels, cassava peel and millet husks but this study produced highest yield using water hyacinth. This study indicated that water hyacinth is mostly available aquatic plant for the production of ethanol. The aim of current work is to understand the usage of water hyacinth as main substrate for bioethanol production using fungal inoculum. The microbial inoculants used for current study reported more potential for the production of bioethanol. This current work gives more economical value to water hyacinths and it can be cleared from all the waterways. [ABSTRACT FROM AUTHOR]

The aim of the paper is to examine the performance of molten carbonate fuel cell, which is supplied with a raw bioethanol, i.e. bioethanol which origins directly from fruit fermentation, without pre-treatment of fermentation products. The composition of raw bioethanol was precisely determined and then the impact of raw bioethanol on the degradation of molten carbonate fuel cells was examined. Steam to carbon ratio of the biofuel has been determined as 5.7 (in comparison to stoichiometry of reaction) which allowed for estimation of hydrogen production during steam reforming process taking place in the anode channel. The results in the form of current-voltage curve was obtained and compared with the same fuel cell fed with pure hydrogen, while the amount of hydrogen was defined as identical with the one after steam reforming of biofuel taking place in the nickel anode channel. Relevant literature studies were focused on the purified fuel or examination of the impact of individual components. Our study proved carbon deposition is not a problem, however solid particles contamination in fermentation product makes it impossible to use fuel cell fueled with fermentation product for longer periods, and prior to supplying fuel cell the bioethanol purification is required. A raw biofuel with its impurities did not have any impact on the anode and current collector surface from physical point of view, but Electrochemical Impedance Spectroscopy analysis shows visible increase of ohmic loses. • Homemade first generation bioethanol composition have been examined. • Manufactured bioethanol has been delivered directly to the MCFC anode without purification. • Performance of MCFC fueled with impure bioethanol has been investigated. • Effect of steam reforming for hydrogen generation and steam to carbon ratio were evaluated. • Pollution on the anode after cell operation was investigated with SEM and EIS. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

Algal biomass is a promising renewable feedstock for biofuel production that does not compete with food crops or require complex pretreatment like lignocellulosic biomass. This study examined biofuel production from two algae: Alkalinema pantanalense (cyanobacteria) and Chlorella vulgaris (green alga). Although there was no significant difference in their biomass, A. pantanalense showed a higher carbohydrate content (204.96 mg L−1) than C. vulgaris (156.07 mg L−1). To maximize reducing sugar release, three pretreatments were tested: thermotacidic, biological using the new fungal isolate Trichoderma longibrachiatum , and biological with nanoparticles. Biological pretreatment with Mg Zn ferrite nanoparticles (MZF-nps) at 60 mg L−1 concentration gave the best results, significantly enhancing cellulase, β-glucosidase and filter paper cellulase activities by 20.94 % (A. pantanalense) and 18.63 % (C. vulgaris). For biohydrogen production, the co-culture of Klebsiella pneumoniae and Enterobacter cloacae resulted in faster fermentation and improved hydrogen evolution compared to individual cultures. A. pantanalense and C. vulgaris yields were 35.1 mL g−1 and 26.6 mL g−1 dry weight, with maximal cumulative production of 2478 mL L−1 and 1845 mL L−1, respectively. Optimized Saccharomyces cerevisiae bioethanol fermentation conditions included 72 h incubation, 5 % inoculum, 30 °C, pH 5 under shaking condition, yielded 11.2 g L−1 (A. pantanalense) and 7.2 g L−1 (C. vulgaris). Furthermore, MZF-nps hydrolysate significantly increased bioethanol production, by 4.2-fold (A. pantanalense) to 32.45 g L−1 and 3.48-fold (C. vulgaris) to 28.6 g L−1, compared to thermoacidic pretreatment. In summary, biological pretreatment demonstrates the potential of algal biomass as a renewable feedstock for sustainable biofuel production. • Algal biomass is a promising renewable feedstock for biofuel production. • Biological pretreatment with nanoparticles increased fermentable sugars and biofuel yields. • Optimized fermentation conditions improved bioethanol yields from algal biomass. • MZF-NP increased bioethanol production up to 4.2-fold over thermoacidic pretreatment. • Co-culturing bacteria improved biohydrogen yield from algal biomass over individual strains. [ABSTRACT FROM AUTHOR]

Researchers are developing new techniques for clean fuel production due to environmental problems such as global warming. In this respect, bioethanol is considered among the most important renewable fuels. This study aims to investigate the energy cycle and estimate the potential environmental effects of ethanol production from sugarcane bagasse in Iran. To this end, ethanol's life cycle assessment (LCA) was conducted based on the "cradle to gate" approach. This assessment includes three stages of sugarcane farming, transportation to the factory, and bioethanol production. This study defines three scenarios for bioethanol production from sugarcane bagasse using the fermentation conversion process: fermentation, bagasse burning for electricity, and combined bioethanol and electricity production. The third scenario was chosen as the best. However, in environmental analysis, it showed the most negative effects on environmental indicators, especially in cases of abiotic depletion and global warming potential. Scenario 1 showed better results than the others. The results showed that electricity, diesel fuel, and nitrogen fertilizer had the greatest environmental impact in the mentioned process. Moreover, by replacing fossil fuels with clean energies, more energy efficiency and less environmental consequences can be achieved because fossil fuels cause air pollution leading to acid rain, eutrophication, damage to forests, and harm to wildlife. Our results show that the bioethanol production process using sugarcane bagasse as feedstock requires 27.13 MJ/L input energy, while the total output energy is 40.44 MJ/L. Energy indices were calculated, with values of 1.49, 0.037, 27.13, and 13.31 for energy ratio, efficiency, intensity, and net energy addition, respectively. [ABSTRACT FROM AUTHOR]

Extortionate demand of global bioethanol has led to a burgeoning interest in finding the alternative sources of biofuel. For this purpose, researchers are interested in microalgae because of its biorefinery applications and ability to produce biofuels, and other value-added products. Bioethanol is the most extensively used renewable fuel and is one of the realistic candidates for addressing environmental issues and mitigating the low base of oil supply. Chlorella sorokiniana can be considered as the most eminent source of bioethanol due to the accumulation of high levels of carbohydrates which can significantly be converted into renewable, cost-effective, and eco-friendly bioethanol. Keeping in view the importance of pretreatment for the efficient production of biofuels, the present study was targeted to determine the optimum conditions required for the chemical pretreatment. The selected microalgae strain was cultivated under mixotrophic and photoautotrophic conditions at laboratory and pilot scales. For mixotrophic cultivation, 0.2% (v/w) of molasses was used as an organic source of carbon. The reducing sugar content of Chlorella sp. was studied by pretreating the dried biomass with dilute H2SO4 and NaOH at 3%, 5%, 7%, and 9% (v/v) concentrations. Mixotrophic cultivation conditions along with 3% H2SO4 pretreatment showed the most efficient recovery of entrapped sugars from algal cell wall consequently producing maximum amount of bioethanol. At lab scale, the biomass cultivated under photoautotrophic and mixotrophic conditions and pretreated with 3% acid produced maximum of 10.96 and 16.07 g/L ethanol, respectively, while maximum ethanol production of biomass cultivated under mixotrophic conditions in alkaline pretreatment was 12.21 g/L at 9% NaOH and in biomass cultivated under photoautotrophic conditions maximum 9.89 g/L of ethanol production was estimated at 5% NaOH. During pilot-scale cultivation, the mixotrophically cultivated biomass pretreated with acidic medium produced 13.45 ± 4.31 g/L ethanol and photoautotrophically cultivated biomass resulted into 10.8 ± 6.31 g/L of ethanol with 88 and 83% of substrate reduction, respectively. This study proofs that biomass of C. sorokiniana pretreated with H2SO4 can act as a possible alternative for the sustainable production of bioethanol. Optimum growth of C. sorokiniana by using molasses in mixotrophic culture conditions also addresses the ability of microalgae to treat wastewaters and use waste materials as a carbon source. For the commercial production of bioethanol from microalgae, results of the present study will be helpful. [ABSTRACT FROM AUTHOR]

Among the biggest issues facing the world now are fuel shortages and water contamination. Therefore, the goal of the current study was directed to produce bioethanol from Jatropha curcas leaves and use the residual wastes in the form of composite sheets for crystal violet (CV) removal. The leaves were collected from Jatropha curcas, irrigated by various irrigation sources; sewage-water (A), sewage-water-sludge (B), and tap water (C). The acid hydrolysis (4% H2SO4) of these leaves demonstrated that the hydrolysis of the Jatropha curcas leaves (A) produced higher values of total reducing sugars (≈ 21 g/l) than other leaves (B &C). Moreover, the bioethanol concentrations obtained from the fermentation of this hydrolysate (A) at the bioreactor scale using Candida tropicalis and Saccharomyces cerevisiae (≈10 and 7 ml/l, respectively) were relatively increased compared to the flask level (≈7 and 5 ml/l, respectively). Afterwards, the unhydrolyzed wastes were dried, grinded, and embedded in polyvinyl chloride (PVC) polymer forming sheets. The sheets were characterized using FT-IR, SEM, swelling, and porosity. The highest CV removal percent of 95.39%, after optimization, was achieved at 100 ppm crystal violet concentration using 2.5 g/l from PVC-A composite sheet after 180-min contact time. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between corn prices in Brazil and the international market, considering a rise in corn ethanol production in Brazil's Midwest region since 2017. Did the entry of the corn ethanol industry in Brazil affect the relationship between domestic and international corn prices? A cointegration analysis was made with a monthly time series from May 2005 to August 2023 controlling for different exogenous events or shocks that may have affected global agricultural markets. The study's findings indicate a stable long‐term relationship between the international and Brazilian corn prices, with changes in international prices being predictors of variations in Brazilian domestic prices, while the opposite was not statistically supported. The study also found no evidence to support the claim that the entry of the corn ethanol industry into Mato Grosso state in 2017 impacted the prices paid to local producers. Therefore, the increase in Brazilian corn prices cannot be attributed to additional demand for corn by local mills, an important result that contributes to discussions such as food versus fuel and indirect land use change. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass, the most abundant natural resource on earth, can be used for cellulosic ethanol production but requires a pretreatment to improve enzyme access to the polymeric sugars while obtaining value from the other components. γ‐Valerolactone (GVL) is a promising candidate for biomass pretreatment since it is renewable and bio‐based. In the present work, the effect of a pretreatment based on GVL on the enzymatic saccharification of white birch was evaluated at a laboratory scale and the importance of the washing procedure for the subsequent saccharification was demonstrated. Both the saccharification yield and the production of cellulosic ethanol were higher using a noncommercial enzyme crude from Talaromyces amestolkiae than with the commercial cocktail Cellic CTec2 from Novozymes. Furthermore, the production of extracellular cellulases by T. amestolkiae has been optimized in 2 L bioreactors, with improvements ranging from 40% to 75%. Finally, it was corroborated by isoelectric focus that optimization of cellulase secretion by T. amestolkiae did not affect the pattern production of the main β‐glucosidases and endoglucanases secreted by this fungus. [ABSTRACT FROM AUTHOR]

The increase in rice straw production and their non-utilization is a major global challenge. Even though it is an eco-friendly feedstock for the bioconversion of energy production separation of cellulose from the rice straw fiber is one of the main limitations that obstruct the application of such lignocellulosic feedstock. In the present research work, acid-alkali pretreatment technologies were applied to the rice straw to increase enzymatic accessibility and improve cellulose digestibility. The rice straw was physically and chemically treated and the chemical pretreatment with 4% sodium hydroxide released a maximum cellulose of 120.33 mg/L. The constituents of cellulose, hemicellulose, and lignin were estimated while the functional groups were identified by using Infrared spectroscopy. Further, the morphological and structural characterization between the untreated and the treated rice straw were analyzed by Scanning Electron Micrograph (SEM) analysis which demonstrated a highly distorted structure in the pretreated biomass. Rice straw was used for the production of bioethanol, with simultaneous saccharification fermentation (SSF) yielding higher ethanol (21.77%) than separate hydrolysis fermentation (SHF) (11.65%) by using commercial enzymes and yeast isolates, and optimal production conditions were determined. Pre-treating rice straw with 4% NaOH, optimized enzyme concentration (2:1:1), and SSF with Saccharomyces cerevisiae or 72-hour incubation at pH 4 yielded the highest bioethanol production. mutagenesis using UV rays and chemicals like Ethidium Bromide (EtBr) and Ethyl Methane Sulfonate (EMS) improved bioethanol yield, with EMS treatment exhibiting the most significant increase i.e. with the wild strain (21.77%) and with the mutant strain (24.29%) was achieved. Such a strategy will be eco-friendly and effective for the reduction of biomass and the production of bioethanol at a much lower cost. [ABSTRACT FROM AUTHOR]

Pretreatment is an important step in lignocellulosic bioethanol production which aims to reduce lignin content and break down lignocellulosic structure thereby increasing the accessibility of enzymes in hydrolysis. Therefore, this research explored the pretreatment process on oil palm empty fruit bunch (EFB) with CO2 impregnation followed by alkali explosion. EFB was impregnated with CO2 at 5 °C for 12 h. After impregnation, EFB was mixed with 2.5 M of NaOH solution (1:5 of S/L ratio) in an alkali explosion reactor. Alkali explosion was conducted at 150 °C, 4 kg/cm2 of pressure with the variation of reaction time for 15, 30, and 45 min. The parameters analyzed in this study include EFB recovery, EFB composition and characteristics, glucose yields, and ethanol yields. EFB composition was analyzed as cellulose, hemicellulose, and lignin while the characteristics of the EFB were examined in functional groups. The results indicated that combined pretreatment using CO2 impregnation followed by 15 min of alkali explosion obtained higher delignification of EFB, glucose, and ethanol yield than only alkali explosion for 30 min. The highest glucose and ethanol yields were 99.33 and 83.80 w/w% of glucose mass in EFB, respectively. These results prove that CO2 can be used as an impregnation agent in lignocellulosic pretreatment and could be combined with alkali explosion. [ABSTRACT FROM AUTHOR]

Bioethanol, a lignocellulosic biofuel, has increased energy sustainability and lessened the environmental effects associated with energy production. Thysanolaena latifolia is a common weed found in the northern part of Thailand that is considered non-food biomass, with a high biomass productivity of approximately 10.2 kg/year. Here, we evaluated the potential of T. latifolia biomass as an environmentally friendly material source for producing alternative bioethanol. To this end, we treated the feedstock under mild conditions using various concentrations of phosphoric acid to create ideal conditions for enzymatic hydrolysis. Pretreatment with 75% phosphoric acid yielded the highest solid recovery (55.8 ± 0.6%) and glucans (93.0 ± 0.3%). Additionally, the hydrolysis efficiency and glucose yield of treated biomass were significantly improved. As a result, the liquid hydrolysate from T. latifolia used for ethanol fermentation by Saccharomyces cerevisiae TISTR 5339 generated 8.9 ± 0.0 g/L ethanol. These findings demonstrate that glucose derived from liquid hydrolysate is a promising sustainable carbon source for producing ethanol from T. latifolia feedstock. Thus, using T. latifolia as a feedstock for generating ethanol can improve the efficiency of bioenergy production. [ABSTRACT FROM AUTHOR]

Coffee beans, a popular commodity in the world, are processed into coffee, which generates a considerable quantity of spent coffee grounds (SCGs). However, SCGs, a byproduct rich in hemicellulose, poses a challenge due to fermentable sugar loss during conventional pretreatment. This study investigates the efficient production of bioethanol from SCG using an optimized liquid hot water (LHW) pretreatment combined with separate hydrolysis and fermentation (SHF) process. LHW pretreatment at 180 °C for 20 min with a high solid-to-liquid ratio (SLR) of 1:6 (w/v) was optimized to disrupt the lignocellulosic structure and retain high levels of fermentable sugars, which included mannose and glucose. This approach achieved a bioethanol concentration of 15.02 ± 0.05 g/L and a productivity rate of 1.252 g/(L·h), demonstrating the efficiency of this integrated process. Interestingly, the high SLR LHW pretreatment significantly reduces water usage and enhances product concentration, offering a promising, environmentally friendly, and economically viable method for industrial bioethanol production from SCGs without the necessity of detoxification. [ABSTRACT FROM AUTHOR]

In this study, ethanol was produced via thermal-acid hydrolysis, enzymatic saccharification, and fermentation from the red seaweed Eucheuma denticulatum as a biomass. Also, the removal and further recovery of 5-hydroxymethylfurfural (5-HMF) from hydrolysates were investigated. The thermal-acid hydrolysis produced 38.37 g/L monosaccharides and 6.55 g/L 5-HMF under the optimized condition of 13.7% (w/v) seaweed slurry and 479 mM H2SO4 at 121 °C for 54 min. More monosaccharide (6.43 g/L) was obtained from subsequent enzymatic saccharification using 8 U/mL of commercial enzyme C-Tec2 at 45 °C for 36 h. By detoxification, 88.0% of 5-HMF was removed from seaweed hydrolysates using a 1:1 ratio of polyethylenimine (PEI) to 5-HMF (g/g) at a pH of 11.0 for 15 min. Ethanol fermentation of E. denticulatum hydrolysate was performed using wild-type and galactose-adapted Saccharomyces cerevisiae. The ethanol concentration was maximized to 19.56 g/L (YEtOH = 0.43 g/g) by fermenting detoxified E. denticulatum hydrolysate with galactose-adapted S. cerevisiae Furthermore, for the valuation of 5-HMF (removed from hydrolysate) as a platform chemical, 85.6% of 5-HMF was recovered from the PEI-5-HMF solution by H2SO4 at pH 1.0. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant renewable material in nature, which is converted to simple sugar, glucose, by cellulase enzymes. Cellulase enzymes are one of the most important industrial enzymes that are widely used in the production of biofuels. This study aimed to use wheat straw as a carbon source for Saccharomyces cerevisiae yeast cells to produce bioethanol. Physical grinding and phosphoric acid plus hydrogen peroxide chemical pretreatment methods were carried out for the removal of lignin and hemicellulose from the structure of wheat straw and obtaining a cellulose-rich material. Thermophilic filamentous fungi were isolated from cow manure, and two isolates were selected based on the levels of endoglucanase, exoglucanase, and total cellulase activities and identified based on DNA sequences of internal transcribed spacer regions. Hydrolysates were obtained from enzymatic hydrolysis of pretreatment wheat straw by thermophilic cellulase enzymes. Fermentation of Saccharomyces cerevisiae yeast cells was performed in hydrolysates for bioethanol production. Aspergillus fumigatus isolate indicated 147.11, 515.9, and 453.78 U/mg wheat straw for exoglucanase, endoglucanase, and total cellulase activities, respectively. These activities were, respectively, measured as 380.35, 730.24, and 372.76 U/mg wheat straw for Rhizomucor pusillus isolate. Pretreatment procedures functioned efficiently and increased the cellulose part of wheat straw up to 88.91%. Hydrolysates of pretreated wheat straw (obtained from Aspergillus fumigatus and Rhizomucor pusillus cellulase activities) resulted in 21.88 and 24.02 g/L (4.05 and 5.31%) bioethanol by Saccharomyces cerevisiae yeast fermentation, respectively. It seems that utilizing thermophilic cellulase enzymes and wheat straw is a promising economic process for bioethanol production. [ABSTRACT FROM AUTHOR]

A sustainable bioeconomy in agricultural and agro-industrial production must inevitably involve the sustainable use of agricultural residues through zero-waste processes. Corn cob is considered crucial agricultural waste as 278 and 293 million tons were produced worldwide in 2022 and 2023, respectively. Corn cob hydrolysates, which are abundant in xylose and glucose, could be efficiently utilized for xylitol and ethanol production through the cultivation of recycling the yeast strain Candida magnoliae TISTR 5664 in the single-stage and sequential-stage co-production of these products. The statistically significant maxima (p ≤ 0.05) ethanol concentrations were improved by 7.8% (49.9–51.7 g/L or 91.3–95.6% of the theoretical) from the single stage of ethanol production employing recycled cells and 9.9% (50.9–54.1 g/L or 77.3–83.9% of the theoretical) from the second step of sequential-stage co-production using recycled cells without xylitol accumulation. Conversely, the single-stage xylitol production utilizing recycled cells under microaerobic conditions resulted in a statistically significant lower (p ≤ 0.05) xylitol concentration by two folds relative to the control, while ethanol concentration was elevated by almost double. The statistically significant maximum (p ≤ 0.05) xylitol was achieved at 25.9 g/L (58.6% of the theoretical) when sequential-stage co-production was initiated in the first step with fresh inoculum only and not recycled cells. The sequential-stage co-production of xylitol and ethanol presented the potential for statistically significant improvement (p ≤ 0.05) of both xylitol and ethanol production processes. [ABSTRACT FROM AUTHOR]

The pretreatment of lignocellulosic biomass such as Miscanthus grown on marginal agricultural land is very challenging and requires severe conditions to fractionate cell wall polymers for further valorization. The current study aimed to determine organic acid-based mild conditions to pretreat contrasting lignocellulosic Miscanthus genotypes for the efficient fractionation of cell wall components, with special focus on hemicellulose extraction. In doing so, five Miscanthus genotypes were subjected to four different acid treatments (sulfuric acid, oxalic acid, malonic acid, and citric acid) in a vertical high-pressure steam sterilizer. The results demonstrated that, among the organic acids, oxalic acid was identified as the most effective pretreatment solvent for hemicellulose separation, whereas citric acid yielded the highest amount of galacturonic acid, varying from 15 to 17 mg mL−1 across genotypes. One best performing genotype was selected for the enzymatic hydrolysis. Overall, M. floridulus genotypes exhibited the optimal quality traits for efficient bioconversion with second best in terms of ethanol production potential. [ABSTRACT FROM AUTHOR]

The article presents the definition of bioindustry, in particular biorefinery. The technology for obtaining synthetic fuel EtG (Ethanol to Gasoline) in a plant using bioethanol from food waste was presented. The physicochemical properties of EtG fuel were presented. EtG fuel stands out due to its limited content of benzene and sulfur and a low content of mechanical impurities and heavy metals. EtG fuel can be considered a replacement fuel for motor gasoline. The results of exhaust emissions tests from vehicles with spark-ignition engines in the WLTC test on a hot and cold engine were presented. It was found that EtG fuel is characterized by lower specific distance emissions of CO, NOx, and CH4 and slightly higher specific distance emissions of NMHC when starting a cold engine compared to gasoline, while the specific distance emission of CO2 for both fuels were very similar. [ABSTRACT FROM AUTHOR]

The abundantly available waste banana pseudostem fibers have attracted the paper and textile industries, however the stem-sap extracted during fiber processing remains underutilized. Although this sap comprising cellulosic sugars holds potential as a feedstock, its commercial viability in the renewable energy sector remains a challenge. Our study delves into this untapped resource by mechanically extracting sap from banana pseudostems and enhancing its reducing sugar content to approximately 35.5 g/L through acid hydrolysis and detoxification without concentrating the sap. Using separate batch fermentations with pentose and hexose fermenting strains such as Pichia stipitis NCIM 3499 and Saccharomyces cerevisiae ATCC 2601, we achieved bioethanol production efficiencies of 67.5 % and 70.03 %, respectively. Yield and cost analyses confirmed the feasibility of this approach for industrial application in low-economy settings. Furthermore, gene-interaction network and functional enrichment analysis identified 63 key genes involved in carbohydrate metabolism and ethanol conversion pathways within the fermenting organisms. Among these, the PGK1 gene and its direct interactors emerged as promising targets for future biotechnological enhancements aimed at boosting bioethanol production. This study not only underscores the renewable energy potential of unconcentrated banana pseudostem sap but also paves the way for innovative genetic interventions to optimize bioethanol yields.