Littérature scientifique sur le sujet « Bioethanol, Biodiesel, Hydrolysate »

Castor plant is used commonly for oil extraction and biodiesel synthesis. However, the residues during pruning are not being used effectively. These residues have the potential to be used as feedstock to produce bioethanol and other by-products. The present work assessed the eco-friendly autohydrolysis pretreatment of castor plant pruning residues at different severity factors (R0), applying a range of temperatures from 100 °C to 200 °C. The hydrolysis of pretreated solids was carried out using a commercial cellulases complex at different solid and enzyme loadings. The enzymatic hydrolysate with a higher glucose concentration was further subjected to fermentation using Saccharomyces cerevisiae ATCC 4126. The results showed an efficient xylan hydrolysis (77.5%) and a preservation of glucan up to 83% in the solids pretreated at an R0 of 5.78. The enzymatic hydrolysis of the pretreated solids at an R0 of 5.78 showed a glucose release of 2.9-fold higher than non-pretreated material. In the hydrolysate fermentation, a maximum ethanol production of 50.5 g/L was achieved (equivalent to 6.4% v/v), corresponding to a conversion efficiency of 98% and a biomass-to-ethanol conversion yield of 93.0 g of ethanol per kilogram of feedstock.

AbstractThe work focuses on studying the solubility and stability of dissolved bioethanol as a fuel additive in different fuel blends of gasoline, diesel, 50% diesel/50% biodiesel. Dissolved ethanol fuel appears as particles with a unique size distribution inside the whole fuel blends, and its stability was measured in this work. Bioethanol dissolved fuel particles stability was improved after blending the bioethanol with 50% diesel/50% biodiesel than pure diesel or pure gasoline fuel alone. The obtained results reveal that the lowest bioethanol particles stability was obtained when commixed with gasoline and the suspended ethanol particles completely accumulated at different concentrations of bioethanol in the fuel blends of 2%, 4%, 6%, 8%, 10%, and 12% by volume after 1 h of mixing time. Furthermore, the measured data of the bioethanol particles size distribution reveals that the suspended stability in the diesel blend improve slightly for all bioethanol concentrations of 10%, 15%, 20%, 25%, and 30% by volume. While the bioethanol concentrations of 5% show acceptable particles stability and size distribution during the whole experiments time. Obtained results show that bioethanol suspended particles stability was enhanced for 50% diesel/50% biodiesel blend with different bioethanol concentrations of 5%, 10%, 15%, 20%, 25%, and 30% by volume basis. However, the size of the particles increased as the bioethanol concentration rose with the passage of time.

Abstract Microalgae accumulate abundant lipids and are a promising source for biodiesel. However, carbohydrates account for 40% of microalgal biomass, an important consideration when using them for the economically feasible production of biodiesel. In this study, different acid hydrolysis and post-treatment processing of Chlorella sp. ABC-001 was performed, and the effect of these different hydrolysates on bioethanol yield by Saccharomyces cerevisiae KL17 was evaluated. For hydrolysis using H2SO4, the neutralization using Ca(OH)2 led to a higher yield (0.43 g ethanol/g sugars) than NaOH (0.27 g ethanol/g sugars). Application of electrodialysis to the H2SO4 + NaOH hydrolysate increased the yield to 0.35 g ethanol/g sugars, and K+ supplementation further enhanced the yield to 0.41 g ethanol/g sugars. Hydrolysis using HNO3 led to the generation of reactive species. Neutralization using only NaOH yielded 0.02 g ethanol/g sugars, and electrodialysis provided only a slight enhancement (0.06 g ethanol/g sugars). However, lowering the levels of reactive species further increased the yield to 0.25 g ethanol/g sugars, and K+ supplementation increased the yield to 0.35 g ethanol/g sugars. Overall, hydrolysis using H2SO4 + Ca(OH)2 provided the highest ethanol yield, and the yield was almost same as from conventional medium. This research emphasizes the importance of post-treatment processing that is modified for the species or strains used for bioethanol fermentation.

Groundnut shell is considered to agro-industrial waste product and is rich in lignocellulose materials. It is obtained after the removal of groundnut seed from its pod and used as fodder for cattle. Duc et al., (2019) elaborately reviewed beneficial uses groundnut shells for commercial and industrial purposes and listed production of various bio-products such as biodiesel, bioethanol, and nano-sheet. The aim of this work was to study the production of polyhydroxy butyrate (PHB) using groundnut shells as the carbon source after hydrolysate. Groundnut shell was pre-treated with alkaline reagent with 0.5M, 1M, and 1.5M, of potassium hydroxide and acid hydrolysis with 30%, 50%, and 70%, of sulphuric acid. Combined alkali (1M of potassium hydroxide) and acid (70% sulphuric acid) pre-treatment of groundnut shell yield maximum reducing sugar. In addition, with pre-treated groundnut shell, various pH level (6, 7, & 8), KH2PO4 (100mg/l, 200mg/l and 300mg/l), and temperature (250C, 300C and 350C) are also test for PHB production. Bacillus circulans (MTCC 8167) significantly utilized the hydrolysate substrate and produced the maximum amount PHB (7.6 ± 0.2 g L-l) with pH level 7 and 300C with 100mg/l of KH2PO4. A detailed study of the functional group was also done using FTIR and NMR. Through biochemical pre-treatment, an in-expensive groundnut shell was converted into a valuable bio-product in order to achieve the minimum waste production.

The annual global fish production reached a record 178 million tonnes in 2020, which continues to increase. Today, 49% of the total fish is harvested from aquaculture, which is forecasted to reach 60% of the total fish produced by 2030. Considering that the wastes of fishing industries represent up to 75% of the whole organisms, the fish industry is generating a large amount of waste which is being neglected in most parts of the world. This negligence can be traced to the ridicule of the value of this resource as well as the many difficulties related to its valorisation. In addition, the massive expansion of the aquaculture industry is generating significant environmental consequences, including chemical and biological pollution, disease outbreaks that increase the fish mortality rate, unsustainable feeds, competition for coastal space, and an increase in the macroalgal blooms due to anthropogenic stressors, leading to a negative socio-economic and environmental impact. The establishment of integrated multi-trophic aquaculture (IMTA) has received increasing attention due to the environmental benefits of using waste products and transforming them into valuable products. There is a need to integrate and implement new technologies able to valorise the waste generated from the fish and aquaculture industry making the aquaculture sector and the fish industry more sustainable through the development of a circular economy scheme. This review wants to provide an overview of several approaches to valorise marine waste (e.g., dead fish, algae waste from marine and aquaculture, fish waste), by their transformation into biofuels (biomethane, biohydrogen, biodiesel, green diesel, bioethanol, or biomethanol) and recovering biomolecules such as proteins (collagen, fish hydrolysate protein), polysaccharides (chitosan, chitin, carrageenan, ulvan, alginate, fucoidan, and laminarin) and biosurfactants.

The success of the biorefinery concept will require efficient, robust and versatile cell factories. Currently, the major part of industrial microorganisms are used because of historical grounds, rather than being selected for a specific application. Additionally, demands for increased productivity, wider substrate range utilization, and production of nonconventional compounds lead to a great interest in further improving the currently used industrial workhorses (hosts) and the selection or development of strains with novel properties. The model yeast Saccharomyces cerevisiae is the main microorganism used for first generation ethanol production. When moving from first to second generation of production, one of the major obstacles for a viable development is the toxic effect of compounds released during the pre-treatment of lignocellulosic biomasses, which are the more sustainable feedstock utilized. In the first part of this work, two different approaches to improve S. cerevisiae tolerance to compounds deriving from biomass pre-treatment are described. Firstly, the effects of overexpressing genes encoding the transcription factor (YAP1) and the mitochondrial NADH-cytochrome b5 reductase (MCR1) was evaluated in an industrial xylose-consuming S. cerevisiae strain. During batch fermentation on undiluted and undetoxified spruce hydrolysate overexpression of either genes resulted in faster hexose catabolism. The second approach revealed that acetic acid tolerance of S. cerevisiae can be increased by engineering it to endogenously produce L-ascorbic acid (L-AA). In the second part of the work, since the currently used industrial yeasts represent only the tip of the proverbial iceberg of the genetic diversity present in nature, different non-saccharomyces yeasts were investigated for their potential industrial applications: Kluyveromyces marxianus (CBS 712), the oleaginous yeasts Rhodosporidium toruloides (DSM 4444), Lipomyces starkeyi (DSM 70295) and Cryptococcus curvatus (DSM 70022), Zygosacchromyces bailii and finally, Candida lignohabitans. Overall, the work performed resulted in the development of industrial S. cerevisiae strains with improved traits that can match the requirements of lignocellulosic hydrolysate fermentation. The work also contributed to a better understanding of the metabolism and physiology of different non-saccharomyces yeasts with a great industrial potential.