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This paper investigates bioethanol production from switchgrass, focusing on enhancement of efficiency through various pretreatment methods and comparing two bioethanol production processes: simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF). Physical, chemical, and biological pretreatment processes are applied to enhance the breakdown of switchgrass's lignocellulosic structure. Effects of pretreatments, enzymatic hydrolysis, and fermentation on ethanol yield are discussed in detail. The comparative analysis reveals that SSF yields higher ethanol outputs within shorter times by integrating hydrolysis and fermentation into a single process. In contrast, SHF offers more control by separating these stages. The comparative analysis highlights that SSF achieves higher ethanol yields more efficiently, although it might restrict SHF's operational flexibility. This study aims to provide a comprehensive overview of the current pretreatments, hydrolysis methods, and fermentation processes in bioethanol production from switchgrass, offering insights into their scalability, economic viability, and potential environmental benefits. The findings are expected to contribute to the ongoing discussions and developments in renewable bioenergy solutions, supporting advancing more sustainable and efficient bioethanol production techniques. [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]

One of the key guidelines in the European waste management policy is the diversion of waste from landfills, preventing harmful effects on human health and the environment and ensuring that economically valuable waste materials are efficiently recycled and reused through proper management. The organic fraction of municipal waste is abundant and contains biodegradable ingredients such lignocellulose, starch, lipids, pectin, and proteins, making it suitable for biotechnological production. Taking into account that a large amount of organic waste is disposed of in landfills, within this work, the amount of organic waste disposed of in the landfill in Banja Luka was considered. Four simulation model scenarios of the integrated production of bioethanol and biogas are generated, and their process and economic aspects are discussed. In the first two modelled scenarios, the pretreatment conditions (1% sulfuric acid and a different neutralization agent) were varied, while in the other two, the share of the amount of raw material used for the production of bioethanol, i.e., biogas, was varied (split factor: 10–90%). The modelled plant, with a designed capacity of 6 tons/h of organic waste, is a significant bioethanol producer, generating 5,000,000 L/year. The profitability indicators, when examined, revealed that dedicating a portion of the organic municipal waste input exclusively to biogas production leads to decreased process efficiency. Based on the modeled process parameters, ethanol's minimum feasible selling price is $0.6616 per liter, while regarding the composition of organic municipal waste, carbohydrates have the most significant impact on the viability of the process. The developed model represents an excellent basis for further development of this integrated bioprocess in such a way that it can be modified with new process parameters or economic or ecological indicators and used at all levels of bioprocess design. Additionally, the obtained sustainable integrated bioethanol and biogas production plant models could support forthcoming steps in municipal waste management by providing reliable data on the conditions under which the integrated process of bioethanol and biogas production would take place, as well as the technical feasibility and economic profitability of such organic municipal waste utilization. [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]

In this work, hemp (Cannabis sativa L.) stalks were pretreated with pyrrolidinium acetate [Pyrr][AC] to increase the availability of cellulose for cellulolytic enzymes and thus improve the production of 2G ethanol from reducing sugars. The process was carried out under different temperature and time conditions: The control sample was raw material and deionized water, and the second sample was kept at 21 °C for 24 h. The third sample was kept at 90 °C for 30 min, and the fourth sample was kept at the same temperature for 24 h. For each pretreatment, the extraction of lignin and hemicellulose was determined, as well as the change in biomass composition before and after pretreatment. The stalks of hemp seed contained 41.54% cellulose, 18.08% lignin and 28. 87% hemicellulose. [Pyrr][AC] used to dissolve seed hemp at 90 °C for 24 h was most effective in the extraction of this biopolymer, extracting 3.1% content. After enzymatic hydrolysis, the highest content of reducing sugars was found for samples of hemp stalks that were first pretreated with proton ionic liquid (PIL) and stirred at 90 °C for 24 h. On the other hand, the highest ethanol content (5.6 g/L) after fermentation and yeast viability (56.7%) after 72 h were obtained in samples pretreated at 90 °C and for 24 h. [ABSTRACT FROM AUTHOR]

Despite the significant progress in the research, the problem of finding an efficient method for producing bioethanol from renewable lignocellulosic waste materials remains unresolved. Our investigation aimed to assess the efficacy of ethanol production from sugar beet pulp (SBP) utilising various approaches, including pretreatment variations, enzymatic processes, and microbial hydrolysis. Our research involved using the post-cultivation concentrate of T. viride LOCK 0588 grown in the SBP-based medium as a source of enzymes. The SBP hydrolysis process was carried out for 48 h at 50 °C. The quantity of sugar released, up to 61 g dm−3, through the utilisation of this extract proved to be on par with the outcomes achieved by the application of the commercial Cellic Ctec2 preparation. The final yields of the ethanol production with the use of the coculture of S. cerevisiae (Ethanol Red) and Scheffersomyces stipitis LOCK 0047 strain were in the range 5.1 ± 0.11 kg 100 kg−1 ÷ 5.38 ± 0.11 kg 100 kg−1. These results provide a solid basis for improving larger-scale industrial procedures that involve converting SBP into bioethanol using a cost-efficient approach of microbial hydrolysis with T. viride and a blend of pentose and hexose fermenting yeast. [ABSTRACT FROM AUTHOR]

The supply of waste glycerol is rising steadily, partially due to the increased global production of biodiesel. Global biodiesel production totals about 47.1 billion liters and is a process that involves the co-production of waste glycerol, which accounts for over 12% of total esters produced. Waste glycerol is also generated during bioethanol production and is estimated to account for 10% of the total sugar consumed on average. Therefore, there is a real need to seek new technologies for reusing and neutralizing glycerol waste, as well as refining the existing ones. Biotechnological means of valorizing waste glycerol include converting it into gas biofuels via anaerobic fermentation processes. Glycerol-to-bioenergy conversion can be improved through the implementation of new technologies, the use of carefully selected or genetically modified microbial strains, the improvement of their metabolic efficiency, and the synthesis of new enzymes. The present study aimed to describe the mechanisms of microbial and anaerobic glycerol-to-biogas valorization processes (including methane, hydrogen, and biohythane) and assess their efficiency, as well as examine the progress of research and implementation work on the subject and present future avenues of research. [ABSTRACT FROM AUTHOR]