Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

Study of the Viscosity and Specific Gravity of the Ternary Used Frying Oil (UFO)-Bioethanol-Diesel System

Fossil fuels cover around 80% of global energy consumption. However, the problems linked to their use justify the choice of using biofuel. In order to reduce as much as possible, diesel rate, an increase in the number of additives may be considered. Thus, in this work, the study of the used frying oil (UFO), bioethanol and diesel ternary system was undertaken. It emerges from this study that the addition of bioethanol reduces the viscosity and the density of the ternary system and permits a 90% substitution rate for diesel between the UFO and bioethanol. Finally, the percentage of oil becomes 40% after adding alcohol compared to the binary diesel crude vegetable oil mixture where this rate is 30%.

Advances of macroalgae biomass for the third generation of bioethanol production

In recent years, utilization of renewable sources for biofuel production is gaining popularity due to growing greenhouse gas(GHG) emissions which causes global warming. There has been a great effort in exploring alternative feedstock for bioethanol production. In this context, the production of third-generation bioethanol from macroalgae has emerged as an alternative feedstock to food crop-based starch and lignocellulosic biomass.This is mainly due to the fast growth rate of macroalgae, no competition with agricultural land, high carbohydrate content and relatively simple processing steps compared to lignocellulosic biomass. This review paper provides an insight of recent innovative approaches for macroalgae bioethanol production, including conventional and advanced hydrolysis process to produce fermentable sugar, various fermentation technologies, economic analysis and life cycle assessment. With the current technology maturity, efficient utilization of macroalgae as sustainable source for bioethanol and other value-added chemicals production could be achieved in the near future.

Hydrothermal Pretreatment of Lignocellulosic Materials for Improving Bioethanol Production

With the continued depletion of non-renewable energy resources,it is essential to seek new methods of harnessing clean and renewable energy.In this regard,second-generation bioethanol derived from lignocellulosic biomass has attracted increasing attention in recent years.The choice of the pretreatment method of lignocellulose is critical to the subsequent bioconversion processes.Compared with other conventional chemical pretreatment methods,hydrothermal pretreatment is a simple,low-cost,and economically feasible process that requires water as the only reagent.This paper reviews the research efforts that have been made toward hydrothermal pretreatment of lignocellulosic biomass and focuses on the transformations involving cellulose,hemicellulose,and lignin during this process.

Bioethanol Production from Rice Straw Enzymatically Saccharified by Fungal Isolates, Trichoderma viride F94 and Aspergillus terreus F98

Egypt faces a high population growth rate nowadays, which demands for an increase in agricultural production efficiency. Consequently, agricultural field residues will increase. Rice straw is one of the main agriculture residues in Egypt. So this study was performed on rice straw as a resource for production of bioethanol. Eight microbial isolates, five yeasts and three fungi were isolated from rice straw. Yeast isolates were selected for their ability to utilize different sugars and cellulose. Chipped and grinded rice straw was subjected to different pretreatment methods physically through steam treatment by autoclaving and different doses of gamma γ irradiation (50 and 70 Mrad). Autoclaved pretreated rice straw was further enzymatically treated throughout solid state fermentation process by different fungal isolates;F68, F94 and F98 producing maximum total reducing sugars of 12.62, 13.58, 17.00 g/L, respectively. Bioethanol production by separate microbial hydrolysis and fermentation (SHF) process of rice straw hydrolysate was performed by the two selected fungal isolates;Trichoderma viride F94 and Aspergillus terreus F98 and two yeast isolates (Y26 and Y39). The two yeast isolates have been identified by 18S, RNA as Candida tropicalis Y26 and Saccharomyces cerevisiae Y39. SHF processes by F94 and Y26 produced 45 gallon/ton rice straw while that of F98 and Y39 produced 50 gallon/ton rice straw.

Trehalose and Sucrose Osmolytes Accumulated by Algae as Potential Raw Material for Bioethanol

Currently, obtaining sustainable fuels, such as biodiesel and bioethanol, from cheap and renewable materials is a challenge. In recent years, a new approach being developed consists of producing, sugars from algae by photosynthesis. Sugar accumulation can be increased under osmotic stress (osmoregulation). The aim of this study is to show the pro-duction of sugars from algae, isolated from natural sources, and the effect of osmotic stress on fermentable sugars ac-cumulation. Strain isolation, production of sugars from each alga and the effect of osmotic stress on growth and sugar production are described. Twelve algal strains were isolated, showing growths between 0.6 and 1.8 g of biomass dry weight /L, all with production of intracellular and extracellular sugars. The strain identified as Chlorella sp. showed an increase in sugar production from 23.64 to 421 mg of sugars/g of biomass dry weight after 24 h of osmotic stress with 0.4 M NaCl. Sucrose and trehalose, both fermentable sugars, were the compatible osmolytes accumulated in response to the osmotic stress. The isolated strains are potential producers of fermentable sugars, using the photosynthetic pathway and osmotic stress.

A Review on 1st and 2nd Generation Bioethanol Production-Recent Progress

Today’s society is based on the use of fossil resources for transportation fuels. The result of unlimited consumption of fossil fuels is a severe depletion of the natural reserves and damage to the environment. Depleting fossil reserves and increasing demand for energy together with environmental concerns have motivated researchers towards the development of alternative fuels which are eco-friendly, renewable and economical. Bioethanol is one such dominant global renewable transport biofuel which can readily substitute fossil fuels. Conventionally, bioethanol has been produced from sucrose and starch rich feedstocks (edible agricultural crops and products) known as 1st generation bioethanol;however this substrate conflicts with food and feed production. As an alternative to 1st generation bioethanol, currently there is much focus on advancing a cellulosic bioethanol concept that utilizes lignocellulosic residues from agricultural crops and residues (such as bagasse, straw, stover, stems, leaves and deoiled seed residues). Efficient conversion of lignocellulosic biomass into bioethanol remains an area of active research in terms of pretreatment of the biomass to fractionate its constituents (cellulose, hemicellulose and lignin), breakdown of cellulose and hemicellulose into hexose and pentose sugars and co-fermentation of the sugars to ethanol. The present review discusses research progress in bioethanol production from sucrose, starch and cellulosic feedstocks. Development of efficient technology to convert lignocellulosic biomass into fermentable sugars and optimization of enzymatic hydrolysis using on-site/ in-house enzyme preparation are the key areas of development in lignocellulosic bioethanol production. Moreover, finding efficient fermenting microorganisms which can utilize pentose and hexose sugars in their metabolism to produce ethanol together with minimum foam and glycerol formation is also an important parameter in fermentation. Research has been focusing on the application of genetically modified strains, thermoanaerobes and mixed cultures of different strains in bioethanol production from sucrose, starch and lignocellulosic feedstocks.

Bioethanol Fermentation from Stalk Juice of Sweet Sorghum by Immobilized Yeast

Bioethanol fermentation experiments were conducted in a shaking flask and a 10 L fluidized bed bioreactor with stalk juice of SNTZ No.2 sweet sorghum variety when immobilized yeast was applied. The objectives of the study were to investigate the effects of inorganic salts on ethanol fermentation of sweet sorghum juice and to observe performance of fluidized bed bioreactor. L9（34） orthogonal experimental method was used in shaking flask experiments. Results showed that the influence sequence to improve ethanol yield was （NH4）2SO4, MgSO4, K2HPO4 for SNTZ No.2 sweet sorghum variety. The optimum ratio of K2HPO4, （NH4）2SO4 and MgSO4 were 0.125%, 0.2% and （0.05）%, respectively. At the optimum ratio, the fermentation time was short and the ethanol content was high in fluidized bed reactor fermentation, which were 5 h and 7.2%（v/v）, respectively. The calculated ethanol yield was 93%. The fermentation time was shortened by 1～3 h and ethanol yield at the end of fermentation was increased by 2%8% than without inorganic salts; In addition, the results showed that the fermentation time was about six times shorter in fluidized bed bioreactor with immobilized yeast than that of conventional fermentation technology. Therefore, it can be concluded that the fluidized bed bioreactor with immobilized yeast should be applied for ethanol production from sweet sorghum. And ratio of inorganic salts should be considered for refining bio-ethanol from juice of sweet sorghum stalk in order to shorten fermentation time and increase ethanol yield.

Effect of steam-pretreatment combined with hydrogen peroxide on lignocellulosic agricultural wastes for bioethanol production：Analysis of derived sugars and other by-products

The hydrogen peroxide, a green impregnating agent suitable for lignocellulosic biomass to bioethanol process, was used to pretreat sugarcane bagasse by steam explosion. Two different concentrations of hydrogen peroxide（0.2% and 1%） were investigated. Then, the biomass was hydrolyzed after pretreatment using cellulase. The amount released of：（i） cellobiose;（ii） monosaccharides, as glucose, xylose, arabinose and mannose and（iii） lignocellulose derived by-products, as furans and small organic acids（acetic, formic,and levulinic acid）, was evaluated in the hydrolysate samples, previously pretreated both in the presence and absence of impregnating agent. By adding of hydrogen peroxide in steam-pretreatment, the average yield increase was 12% for glucose and as high as 34% for xylose, and cellobiose yield was decreased of about 30%. No significant increase has been observed in arabinose and mannose yield. Furthermore,the hydrogen peroxide seems not increased the formation of lignocellulose derived by-products during pretreatment process, with the exception of the levulinic acid.

Screening of the effective cellulose-degradable strain and its application in the production of cellulose bioethanol

Strains from the cellulose-containing environment were collected. Primary screening(by filter-paper Hutchison solid culture medium and sodium carboxymethylcellulose solid culture medium) and reelection(by filter-paper inorganic salt culture medium and sodium carboxymethylcellulose Congo red culture medium) indicated that five strains obtained were best suited for high performance cellulose degradation. Determination of sodium carboxymethylcellulose activity(CMCA) and filter paper activity(FPA) was accomplished for each of the five. The strongest of the five in CMCA and FPA was applied to the production of cellulose bioethanol by separate hydrolysis and fermentation(SHF) and simultaneous saccharification and fermentation(SSF) respectively.

Bioethanol Production from <i>Chlorella vulgaris</i>Biomass Cultivated with Plantain (<i>Musa paradisiaca</i>) Peels Extract

The feasibility of nutrient uptake by Chlorella vulgaris using a cheap carbon source such as plantain peel extract was studied and its biomass utilized for bioethanol production. Unripe plantain peels were obtained, processed, infused for 48 hrs, extracted and cultivated with the Chlorella species for a period of fourteen days. The microalgal carbohydrate content was hydrolyzed with acid and enzyme while the hydrolysate fermented with 10% concentration of Saccharomyces sp. and Aspergillus sp. at 30°C and pH 4.5 using Separate Hydrolysis and Fermentation (SHF) and Separate Hydrolysis and Co-culture Fermentation (SHCF) methods. Results show that maximum cell growth of 1.56 (OD) and biomass concentration of 19 g/l were obtained with 48 hrs infusion. The result indicated that C. vulgaris utilized PPE medium as a sole carbon substrate and stimulated the secretion of biomass. The highest reducing sugar of 0.63 mg/ml was obtained after hydrolysis of the biomass, while the ethanol production yield of 0.33 g/l was obtained after fermentation. The ethanol production yield increased with the increase in fermentation time, while the reducing sugar was reduced after five days of fermentation. The highest ethanol percentage of 10.82% v/v was obtained from the distillate. This study showed that plantain peel can be utilized by C. vulgaris which provides a feasible route of reducing production cost of bioethanol from a cheap carbon substrate for biomass and bioenergy production.

Production of Bioethanol at High Temperature from Tari

Many microorganisms can tolerate high-temperature ranges from 37°C - 45°C are called thermotolerant microorganisms. Eighteen such isolates containing various microorganisms were collected from the natural fermented products of Bangladesh in summer for bioethanol production. Cultural, morphological, physiological, biochemical and genetical analysis were carried out under various physiological conditions. Among them, two thermotolerant strains Tari-6, isolated from the Tari (an overnight natural fermented palm juice at around 33°C - 40°C) and Pvt-1, isolated from the Pantavat (an overnight natural fermented rice soaked with tap water at around 35&#176C - 37&#176C), produced high amount of bioethanol, 7.5% (v/v) and 6.5% (v/v), respectively at 37°C. Furthermore, a partial 26S rDNA sequencing results confirmed that the Tari-6 and Pvt-1 encoded Pichia galeiformi and Pichia guilliermondii, respectively, and later one could grow well in media containing Xylose. Our results conclude that these two yeast strains are the potential candidates for bioethanol production.

Fermentative Bioethanol Production Using Enzymatically Hydrolysed <i>Saccharina latissima</i>

The increased demand for machinery and transport has led to an overwhelming increase in the use of fossil fuels in the last century. Concerning the economic and environmental concern, macroalgae with high fermentable polysaccharide content (mainly mannitol, cellulose and laminarin), can serve as an excellent alternative to food crops for bioethanol production, a renewable liquid fuel. In this study, Saccharina latissima, a brown macroalgae readily available on the Norwegian coast was used as the carbohydrate source for the fermentative production of bioethanol. The macroalgae harvested was found to contain 31.31 ± 1.73 g of reducing sugars per 100 g of dry Saccharina latissima upon enzymatic hydrolysis. The subsequent fermentation with Saccharomyces cerevisiae produced an ethanol yield of 0.42 g of ethanol per g of reducing sugar, resulting in a fermentation efficiency of 84% as compared to the theoretical maximum. Using these results, an evaluation of the fermentation process has demonstrated that the brown macroalgae Saccharina latissima could become a viable bioethanol source in the future.

Inexpensive Procedure for Measurement of Ethanol: Application to Bioethanol Production Process

We have developed a spectrophotometric method for measurement of ethanol concentration in any unknown sample using a solvent tri-n-butyl phosphate [TBP, non-alcoholic solvent, density = 0.975 to 0.976, solubility in water = 0.028% (w/v)]. Solvent TBP separates ethanol from the non-hydrolyzed substrates that could interrupt the desired result by reacting with dichromate reagent. Oxidation of ethanol with dichromate reagent imparts blue green-colour to the solvent, which is easily detected by Spectrophotomer at 595 nm. Our established method showed similar results performed by relatively expensive Gas Chromatography (GC) method. In our present study we put forth a cheap alternate method for determining ethanol concentration in any aqueous solution.

Investigation of Novel Plant Maerua Shrub (<i>Maerua subcordata</i>) for Cheap and Efficient Bioethanol Production in Kenya

Bioethanol is an attractive source of energy when compared to fossil fuel. It is renewable and environmentally friendly due to its low toxicity and biodegradability. The first generation bioethanol derived from is limited by the high cost of production of these crops and danger posed to food security. This study investigated the use of wild maerua shrub in production of bioethanol in comparison to cultivated food crops. Fermentation was done using Yeasts Y1, Y2 and Y3. Yeasts Y1 and Y2 were isolated from finger millet malt, while Y3 was the commercial yeast Saccharomyces cerevisiae. Fermented plant samples were distilled, oxidized and analysed at 595nm using UV-Visible spectrophotometer. Statgraphics centurion XVI.I was used for statistical analyses. The concentration (g/L) was obtained from a formula and converted to (g/L).The ethanol concentration (g/L) and productivity (g/L/h) were as follows;cassava (64.052 ± 0.098;1.334), maize (66.670 ± 0.227;1.389), sorghum (62.382 ± 2.148b;1.300) and maerua shrub (61.988 ± 0.160, 1.291) which were significantly higher compared to sugarcane molasses (49.978 g/L, 1.041) when fermented by Y2. Mean ethanol concentration (g/L) and productivity (g/L/h) for plants across all yeasts were comparable (p-value = 0.4239). Maerua Shrub should be used as an alternative sugar source for bioethanol production.

Conversion of Bioethanol to Olefins over ZrO_(2) Catalyst

Ethylene and 1,3-butadiene are important organic chemical raw materials.Petroleum hydrocarbon cracking is the most widely used method for ethylene fabrication worldwide.In this study,the use of a ZrO_(2) catalyst,which can be easily synthesized,for the efficient conversion of bioethanol to ethylene and 1,3-butadiene was analyzed.X-ray diffraction,transmission electron microscopy,temperature-programmed desorption,and Fouriertransform infrared spectroscopy analyses were used to evaluate the surface properties of ZrO_(2).The selectivity of ZrO_(2) toward ethylene and 1,3-butadiene was as high as 98.2%.Catalyst selectivity toward dehydration or dehydrogenation products depends on the nature of the weak acid-base catalytic sites,whereas high-strength base and intermediate-strength acid catalytic sites selectively yield ethylene.

A reliable method for predicting bioethanol yield of different varieties of sweet potato by dry matter content

In this study,we analyzed the potential of using dry matter content for determining ethanol yield of sweet potatoes as one of the raw materials for bioethanol production.We tested dry matter content,total starch content,crude protein content,glucose content,fructose content,sucrose content and fermentation indicators of 29 sweet potato varieties in Henan province.Correlation analysis between main component contents of sweet potato and the fermentation indicators were carried on.The results showed that there was strong linear correlation between dry matter content and bioethanol yield(R^2=0.935).In order to prove the conclusion,we also tested dry matter content and ethanol yield of another24 sweet potato varieties.Based on the dry matter content and linear correlations,we predicted the ethanol yields.We performed correlation analysis between the predicted values and the measured values of bioethanol yield of the 24 sweet potato varieties,and found highly significant positive correlation between the predicted values and the measured values.These results confirmed the reliability of using dry matter content for bioethanol production prediction for sweet potatoes.

Obtaining Bioethanol through Hydrolytic Treatment of Agro-Industrial Banana Residues

The banana is a food of great importance and it is consumed in almost the entire world. However, its harvest generates large quantities of mostly lignocellulosic waste, which can be used for the production of biofuels such as bioethanol. In this work, the potential for bioethanol production from agro-industrial plantain crop residues was evaluated with different operating conditions. A 24?experimental design was used, having as study variables: time of hydrolysis, pH of hydrolysis, concentration time, and fermentation time. The samples used were scraps consisting of a mixture of stems, leaves, and banana peels. The bioethanol obtained was characterized by physicochemical properties such as density, refractive index, and FTIR. As a result, it was obtained that the volume of bioethanol represented higher yields;using NaOH as a hydrolyzing agent, with hydrolysis time of 30 minutes, high fermentation time, and low concentrations. The chemical characterization of banana agro-industrial waste indicated that, the raw material could be considered as a potential source for bioethanol production, since it has a high content of cellulose.

Liquid–liquid equilibrium extraction of ethanol with mixed solvent for bioethanol concentration

The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process.Furfural and benzaldehyde were selected as extraction solvents,with which the solubility of water is small,expecting large distribution coefficient of ethanol.The liquid–liquid two-phase region was the largest with m-xylene solvent,followed by benzaldehyde and furfural.The region of two liquid–liquid phase became larger with the mixed solvent of m-xylene and furfural than that with furfural solvent.The NRTL model was applied to the ethanol–water–furfural–m-xylene system,and the model could well express the liquid–liquid equilibrium of the system.For any solvent used in this study,the separation selectivity of ethanol relative to water decreased as the distribution coefficient of ethanol increased.The separation selectivity with m-xylene was the largest among the employed solvents,but the distribution coefficient was the smallest.The solvent mixture of furfural and m-xylene showed relatively high distribution coefficient of ethanol and separation selectivity,even in the higher mass fraction of m-xylene in the solvent phase.The ethanol extraction with a countercurrent multistage extractor by a continuous operation was simulated to evaluate the extraction performance.The ethanol content could be concentrated in the extract phase with relatively small number of extraction stages but low yield of ethanol was obtained.

Water-recycled Cassava Bioethanol Production Integrated with Two-stage UASB Treatment

Considering limited success in target-hitting discharge from alcohol industry, our attention was directed toward a recycling use of distillery spentwash (DS) in cassava bioethanol production by using a two-stage up-flow anaerobic sludge blanket bioremediation (TS-UASBB). With the TS-UASBB, 2 4 SO , COD, N and P in the effluent from the DS degraded significantly and their concentrations were kept at 0.2 g·L -1 , 2.0 g·L -1 , 1.0 g·L -1 and 15 mg·L -1 , respectively, in 13 batch processes for water-recycled ethanol fermentation. With the effluent used directly as dilution water, no heat-resistant bacteria were found alive. The thirteen-batch ethanol production individually achieved 10% after 48 h fermentation. The starch utilization ratio and total sugar consumption were 90% and 99.5%, respectively. The novel water-recycled bioethanol production process with ethanol fermentation and TS-UASBB has a considerable potential in other starchy and cellulosic ethanol production.