Feedstock For Bioethanol Production Research Articles

Optimization of Enzymatic Saccharification of Alkali Pretreated Parthenium sp. Using Response Surface Methodology.

Parthenium sp. is a noxious weed which threatens the environment and biodiversity due to its rapid invasion. This lignocellulosic weed was investigated for its potential in biofuel production by subjecting it to mild alkali pretreatment followed by enzymatic saccharification which resulted in significant amount of fermentable sugar yield (76.6%). Optimization of enzymatic hydrolysis variables such as temperature, pH, enzyme, and substrate loading was carried out using central composite design (CCD) in response to surface methodology (RSM) to achieve the maximum saccharification yield. Data obtained from RSM was validated using ANOVA. After the optimization process, a model was proposed with predicted value of 80.08% saccharification yield under optimum conditions which was confirmed by the experimental value of 85.80%. This illustrated a good agreement between predicted and experimental response (saccharification yield). The saccharification yield was enhanced by enzyme loading and reduced by temperature and substrate loading. This study reveals that under optimized condition, sugar yield was significantly increased which was higher than earlier reports and promises the use of Parthenium sp. biomass as a feedstock for bioethanol production.

Analysis of Free Sugar and Starch in Oil Palm Trunks (Elaeis Guineensis Jacq.) from Various Cultivars as a Feedstock for Bioethanol Production

ABSTRACTIn this study, oil palm trunks from various plantations in Malaysia were analyzed for their starch content and sugar concentrations in the sap from the trunks as function of storage time as a feedstock for green energy. Glycoside hydrolases of the samples were also measured during storage. Considering three kinds of sugars accumulation in the trunks, the highest increase was from 31 mg/ml to 198 mg/ml after 60 days of storage followed by the second highest from 48~78 mg/ml to 109~133 mg/ml after 15~45 days of storage. Accumulation of the third stages was not observed in most types of trunks. The parenchyma in each trunk had different starch contents, which ranged from 0.33 to 37 wt%. Trunks with higher starch content in the parenchyma cells showed a tendency towards increased sugar concentration in the sap, suggesting that the breakdown of starch within the sap is related to sugar accumulation. Amylase activity in the trunks increased from 0.21 mU/g to 1.54 mU/g during storage. Invertase showed relatively high activity (6.48 mU/g) at around 15 days storage time. Based on the findings in this work, it seems that enzymes played an important role in the breakdown of starch and sucrose during storage of oil palm trunks.

Production of bioethanol from rice straw by simultaneous saccharification and fermentation of whole pretreated slurry usingSaccharomyces cerevisiaeKF-7

Rice straw is one of the most abundant lignocellulosic waste materials worldwide, and it can serve as feedstock for bioethanol production. In this study, ethanol was produced from rice straw by simultaneous saccharification and fermentation (SSF) of the whole pretreated slurry with high solid load. Pretreatment of rice straw using 0.5% (w/w) H2SO4 was performed to increase the efficiency of enzymatic saccharification. Enzymatic saccharification and SSF of the whole pretreated slurry were subsequently performed to evaluate the inhibitory effect on enzymatic saccharification and the final ethanol yield. The result showed that pretreatment was the key for achieving high ethanol yield of the whole pretreated slurry. Rice straw pretreated at 170°C with a solid load of 15% exhibited efficient enzymatic saccharification. By the result of ethanol yields, no inhibitory effect was found when the whole pretreated slurry was subjected to SSF. The ethanol yield of SSF of the whole pretreated slurry was enhanced to 77.3%, compared with the glucose recovery efficiency of enzymatic saccharification of the washed pretreated rice straw, which was 74.4%. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 582–588, 2015

Potential of Jerusalem artichoke (Helianthus tuberosus L.) as a biorefinery crop

The utilization of Jerusalem artichoke in a biorefinery context was not investigated so far. Therefore the aim of this study was to evaluate the potential of this plant as feedstock for production of bioethanol, protein and inulin. We investigated the biomass productivity and chemical composition of 11 different clones, harvested on three occasions during the fall and early winter of 2011. The results obtained showed that cellulose production per hectare was at least double compared to corn stover, rice straw, sugarcane bagasse and wheat straw, showing high bioethanol production potential of Jerusalem artichoke. Although not high (in total <6% of dry matter), protein and lipid levels could be of importance when biomass is utilized in a biorefinery concept. Harvest occasion determined the biomass productivity and chemical composition to a higher degree than the choice of clone. The average biomass productivity was 88% higher in September than in December. Fresh tuber biomass productivity showed large variations between harvests, where the maximum average productivity in December was 3.4 times higher than in September. Inulin content in dry tubers was between 76 and 85% making the plant an excellent crop, for e.g. inulin extraction, production of high fructose syrup or fermentations. Less mature plants were shown to have degree of polymerization (DP) up to 14, which makes biomass useful as dietary fibre, while the inulin DP in tubers harvested later became as low as 6, showing lower potential with respect to plant utilization for dietary purposes. Results obtained clearly demonstrated that crop harvesting time was an important factor affecting biomass productivity and composition.

Optimization of the Supply Chain Associated to the Production of Bioethanol from Residues of Agave from the Tequila Process in Mexico

The Mexican economy is highly dependent on the tequila industry, where there are associated several residues of agave (i.e., the plant used to make tequila), which is lignocellulosic matter that can be used as feedstock for bioethanol production. The residues of agave are obtained in the harvesting sites located in several states of Mexico and from the tequila factories that are mainly located in two places in Mexico. This paper presents an optimization framework for designing a supply chain for the bioethanol production from residues of agave bagasse obtained in the tequila processing in Mexico, where central and distributed bioethanol processing plants are considered. The bioethanol production process in the central and distributed plants is modeled according to conversion factors for the different processing steps obtained from experimental data. The proposed optimization formulation also considers the total available agave and the bioethanol demand in Mexico. Several scenarios are analyzed for the bioethanol production from agave bagasse in Mexico, where positive results are obtained from the reuse of residues of agave bagasse for bioethanol production, obtaining considerable profits and satisfying a significant demand of the gasoline required in the area.

Biofuel from Wastes an Economic and Environmentally Feasible Resource

Environmental arguments centre on the need to reduce greenhouse gas (GHG) emissions for the sake of both the global and local environments. In this respect, the replacement of fossil fuels by biofuels in the transportation sector is necessary to help the reduction of GHG. Climate change impacts have spurred researchers and industry to look at alternate clean energy options. The concentration of CO2 in the earth's atmosphere was about 280 parts per million by volume (ppm) in 1750, before the Industrial Revolution began. By 1994 it was 358ppm and rising by about 1.5ppm per year. If emissions continue at the 1994 rate, the concentration will be around 500ppm, nearly double the preindustrial level, by the end of the 21st century. Carbohydrate biomass is considered as the future feedstock for bio ethanol production because of its low cost and its huge availability.The major carbohydrate materials found in great quantities to be considered, is wheat bran, sugarcane bagasse and rape straw, which can be easily converted in to ethanol by following pretreatment either by acid or enzyme, hydrolysis and distillation process under feasible conditions. The effects of different pH and temperature with enzymatic saccharification treatment on conversion of these biomasses were studied. The produced glucose was fermented to bioethanol, using Saccharomyces cerevisiae yeast in combination with pentose fermenting enzymes as Pitchia stipititis and the amount of produced bio ethanol was measured by gas chromatography. Enzyme treatment at 30°C and pH 5 is an effective treatment method for converting lignocelluloses to glucose. Up to 23.35% glucose v/v could be achieved after enzyme treatment from bagasse than others. Fermentation of treated lignocelluloses shown that glucose after 3 days fermentation the maximum bio ethanol of 19.25% (v/v) by Saccharomyces cerevisiae and 26.75% (v/v) was attained in case of sugarcane bagasse by using Pitchia stipititis in combination with S. cerevisiae. This process is expected to be useful for the bio ethanol production from wheat bran, sugarcane bagasse and rape straw as a source of carbohydrate renewable biomass from abundant agricultural by product.

BIOETHANOL PRODUCTION FROM WATER HYACINTH BIOMASS USING ISOLATED FUNGAL STRAIN FROM LOCAL ENVIRONMENT

Fermentation of sugar released by saccharification of lignocellulosic materials produce bioethanol which is a renewable energy source. There are some technological barriers such as pretreatment, saccharification of cellulose and hemicellulose matrix, and simultaneous fermentation of hexose and pentose sugars which needs to be addressed for efficient conversion of lignocellulosic biomass to bioethanol. The present study evaluated water hyacinth as feedstock for bioethanol production, with the possible strategies by which the conversion to sugars from water hyacinth can be maximized. Effect of alkali pretreatment on WHB was studied. In this study, suitability of the feedstock for production of fermentable sugars using crude enzymes produced on site from isolated fungal strain (F13) from the local environment at CSIR-CMERI, Durgapur (Latitude: 23.55 O ; Longitude: 87.31 O ) was demonstrated where in the highest xylose yield obtained was 236.56 mg/g . Cellulase and xylanase activity was determined for biomass saccharification process. Finally , fermentation of the hydrolysate using pentose fermenting yeast, Pichia stipitis yielded an ethanol concentration of 3.193g/L.

Temperature‐dependent changes in the microbial storage flora of birch and spruce sawdust

Sawdust can be used to make pellets (biofuel) and particle boards and as a potential lignocellulose feedstock in bioethanol production. Microbial activity can affect sawdust quality; hence, we monitored the microbial population in birch- and spruce sawdust after 3 months' storage at various temperatures. Species composition was similar on both materials but was strongly influenced by temperature. Bacteria were present on all materials at all conditions: on birch, 2.8×10(8) , 1.1×10(8) , and 8.8×10(6) , and on spruce, 4.1×10(8) , 5.6×10(7) , and 1.5×10(8) CFU/g DM, at 2, 20, and 37°C, respectively. Dominant bacteria at 2, 20, and 37°C were Pseudomonas spp. (some Enterobacteriaceae spp. present), Luteibacter rhizovicinus, and Fulvimonas sp., respectively. Pseudomonas spp. were absent at ≥20°C. Among microfungi, yeasts dominated at 2°C but were absent at 37°C, whereas molds dominated at 20 and 37°C. Common yeasts included Cystofilobasidium capitatum, Cystofilobasidium infirmominiatum, Candida saitoana, Candida oregonensis, and Candida railenensis. Ophiostoma quercus was a common mold at 2 and 20°C, whereas the human pathogens Aspergillus fumigatus and Paecilomyces variotii dominated at 37°C. Attempts to influence the microflora by addition of the biocontrol yeasts, Wickerhamomyces anomalus and Scheffersomyces stipitis, were unsuccessful, as their growth in sawdust was poor to absent.

Biofuel Production fromBorassus Flabellifer

Fossil fuels are depleting at a faster rate and these sources will vanish by the end of this century. There is an urgent need for alternative fuel source to replace fossil fuel and to further prevent environmental damage by fossil fuel. Biodiesel obtained from esterification of non-edible oils or waste oils or Bioethanol produced from surplus agricultural and lignocellulosic residues blended with diesel or petrol have contributed immensely to reduce fossil fuel consumption and have also contributed towards reduction of noxious gases emission into the environment. The feedstock used for biofuel production should be available in surplus, economical and most preferably should not be of food quality. There are many tree species bearing seeds or fruits with limited applications in coastal India. Of these, Borassus flabellifer a palm tree that bears the fruits annually in bunch of 25–40 fruits per bunch and a well grown tree would bear 8 to 10 such bunches. In the present investigation the fruits of Borassus flabellifer are being evaluated for duel biofuel production, i.e., bioethanol and biodiesel. Even though there is a technical difficulty in extricating the copra of the fruit for biodiesel production, the juice and lignocellulosic fibres obtained from the fruit cover and wet kernel were found to be a promising feedstock for bioethanol production. The feasibility of the feedstock for biofuel production is discussed in this study.

Survey of the total fatty acid and triacylglycerol composition and content of 30 duckweed species and cloning of a Δ6-desaturase responsible for the production of γ-linolenic and stearidonic acids in Lemna gibba

BackgroundDuckweeds, i.e., members of the Lemnoideae family, are amongst the smallest aquatic flowering plants. Their high growth rate, aquatic habit and suitability for bio-remediation make them strong candidates for biomass production. Duckweeds have been studied for their potential as feedstocks for bioethanol production; however, less is known about their ability to accumulate reduced carbon as fatty acids (FA) and oil.ResultsTotal FA profiles of thirty duckweed species were analysed to assess the natural diversity within the Lemnoideae. Total FA content varied between 4.6% and 14.2% of dry weight whereas triacylglycerol (TAG) levels varied between 0.02% and 0.15% of dry weight. Three FA, 16:0 (palmitic), 18:2Δ9,12 (Linoleic acid, or LN) and 18:3Δ9,12,15 (α-linolenic acid, or ALA) comprise more than 80% of total duckweed FA. Seven Lemna and two Wolffiela species also accumulate polyunsaturated FA containing Δ6-double bonds, i.e., GLA and SDA. Relative to total FA, TAG is enriched in saturated FA and deficient in polyunsaturated FA, and only five Lemna species accumulate Δ6-FA in their TAG. A putative Δ6-desaturase designated LgDes, with homology to a family of front-end Δ6-FA and Δ8-spingolipid desaturases, was identified in the assembled DNA sequence of Lemna gibba. Expression of a synthetic LgDes gene in Nicotiana benthamiana resulted in the accumulation of GLA and SDA, confirming it specifies a Δ6-desaturase.ConclusionsTotal accumulation of FA varies three-fold across the 30 species of Lemnoideae surveyed. Nine species contain GLA and SDA which are synthesized by a Δ6 front-end desaturase, but FA composition is otherwise similar. TAG accumulates up to 0.15% of total dry weight, comparable to levels found in the leaves of terrestrial plants. Polyunsaturated FA is underrepresented in TAG, and the Δ6-FA GLA and SDA are found in the TAG of only five of the nine Lemna species that produce them. When present, GLA is enriched and SDA diminished relative to their abundance in the total FA pool.

Optimization of NaOH-catalyzed steam pretreatment of empty fruit bunch

BackgroundEmpty fruit bunch (EFB) has many advantages, including its abundance, the fact that it does not require collection, and its year-round availability as a feedstock for bioethanol production. But before the significant costs incurred in ethanol production from lignocellulosic biomass can be reduced, an efficient sugar fractionation technology has to be developed. To that end, in the present study, an NaOH-catalyzed steam pretreatment process was applied in order to produce ethanol from EFB more efficiently.ResultsThe EFB pretreatment conditions were optimized by application of certain pretreatment variables such as, the NaOH concentrations in the soaking step and, in the steam step, the temperature and time. The optimal conditions were determined by response surface methodology (RSM) to be 3% NaOH for soaking and 160°C, 11 min 20 sec for steam pretreatment. Under these conditions, the overall glucan recovery and enzymatic digestibility were both high: the glucan and xylan yields were 93% and 78%, respectively, and the enzymatic digestibility was 88.8% for 72 h using 40 FPU/g glucan. After simultaneous saccharification and fermentation (SSF), the maximum ethanol yield and concentration were 0.88 and 29.4 g/l respectively.ConclusionsDelignification (>85%) of EFB was an important factor in enzymatic hydrolysis using CTec2. NaOH-catalyzed steam pretreatment, which can remove lignin efficiently and requires only a short reaction time, was proven to be an effective pretreatment technology for EFB. The ethanol yield obtained by SSF, the key parameter determining the economics of ethanol, was 18% (w/w), equivalent to 88% of the theoretical maximum yield, which is a better result than have been reported in the relevant previous studies.

Potato peel as feedstock for bioethanol production: A comparison of acidic and enzymatic hydrolysis

Biofuels are of increasing interest as alternatives to the petroleum-based fuels. In particular, second and third generation advanced biofuels, that could be produced from renewable materials such as agricultural residues appear to be more competitive. In this context, this work has focused on the potential of the potato peel use (PPW), a zero value waste, as feedstock for bioethanol production. First, an economical medium for amylase production from Bacillus sp. UEB-S (amylase UEB-S) was formulated using potato peel (10gL−1) as a carbon source and soy flour (20gL−1) as a nitrogen source. Amylase production reached 15U/mL at flask scale and increased to 87U/mL at fermenter scale. A comparative study between acidic and enzymatic hydrolysis of PPW was investigated. It showed that a combined enzymatic treatment using amylase UEB-S and Amyloglucosidase under optimal conditions gave significant yields of reducing sugars (69gL−1) and ethanol (21gL−1). These results are highly interesting and demonstrate the possibility of substituting commercial enzyme by an onsite produced enzyme as well as the potential of PPW as bioethanol feedstock.

Algal biomass conversion to bioethanol – a step‐by‐step assessment

The continuous growth in global population and the ongoing development of countries such as China and India have contributed to a rapid increase in worldwide energy demand. Fossil fuels such as oil and gas are finite resources, and their current rate of consumption cannot be sustained. This, coupled with fossil fuels' role as pollutants and their contribution to global warming, has led to increased interest in alternative sources of energy production. Bioethanol, presently produced from energy crops, is one such promising alternative future energy source and much research is underway in optimizing its production. The economic and temporal constraints that crop feedstocks pose are the main downfalls in terms of the commercial viability of bioethanol production. As an alternative to crop feedstocks, significant research efforts have been put into utilizing algal biomass as a feedstock for bioethanol production. Whilst the overall process can vary, the conversion of biomass to bioethanol usually contains the following steps: (i) pretreatment of feedstock; (ii) hydrolysis; and (iii) fermentation of bioethanol. This paper reviews different technologies utilized in the pretreatment and fermentation steps, and critically assesses their applicability to bioethanol production from algal biomass. Two different established fermentation routes, single-stage fermentation and two-stage gasification/fermentation processes, are discussed. The viability of algal biomass as an alternative feedstock has been assessed adequately, and further research optimisation must be guided toward the development of cost-effective scalable methods to produce high bioethanol yield under optimum economy.

Bioethanol production from bamboo (Dendrocalamus sp.) process waste

Bamboo as a feed stock for bioethanol production is interesting due to the relatively higher growth rate of these plants and their abundant and sustainable availability in the tropics. Dendrocalamus are bamboo varieties common in India, of which large amounts of biomass is generated annually as byproducts of bamboo processing industries. In the current study, process waste from bamboo industry was evaluated as a feedstock for bioethanol production by enzymatic saccharification. Dilute alkali pretreatment of the biomass resulted in efficient removal of lignin, effectively increasing the concentration of cellulose to 63.1% from 46.7%. Enzymatic saccharification of pretreated biomass was optimized following a response surface methodology and the optimal set of parameters for maximal saccharification was derived. Pretreatment method could recover 64.31% of the total sugar polymers and a hydrolysis efficiency of 82.36% was achieved. Direct fermentation of the enzymatic hydrolysate was efficient with ethanol production being 71.34% of theoretical maximum (3.08% v/v ethanol yield). Material balances were calculated for the entire process from raw biomass to ethanol and the overall process efficiency was found to be ∼43%. The process has the potential to generate 143 L of ethanol per dry ton of bamboo process waste.

Fermentable sugar production from rapeseed straw by dilute phosphoric acid pretreatment

Rapeseed straw, as an agricultural residue, does not compete with food use and it can be used as a feedstock for bioethanol production. In this work, previously to enzymatic hydrolysis, phosphoric acid was used to pretreat this raw material and the influence of the main parameters was evaluated on the enzymatic hydrolysis yields and hemicellulosic sugars recovery in liquid fractions. Experimental design and response surface methodology were applied using pretreatment temperature (146.36–213.64°C), time (4.77–55.23min) and phosphoric acid concentration (0.32–3.68%, w/v) as factors. Considering maximization of the enzymatic hydrolysis yield as optimization criterion, results show that 87% of the glucose content in the raw material can be released by enzymatic hydrolysis at 202°C, 5min and 0.32% H3PO4, which is equivalent to 41.1g sugars/100g rapeseed straw.

Saccharification of alkali treated biomass of Kans grass contributes higher sugar in contrast to acid treated biomass

Economical production of biofuel is prerequisite to depletion of fossil fuel. In recent years, biomass of numerous food crops was used as a feedstock for bioethanol production. Unfortunately, due to limited availability as well as confliction with food, these sources may hold back for continuous production of bioethanol. Therefore, in the present study a waste land crop “Kans grass” was utilized as feedstock for microbial production of bio-ethanol. The Kans grass biomass obtained after NaOH pretreatment at optimum conditions (in term of lignin removal) was subjected to enzymatic saccharification by using crude enzyme (obtained from Trichoderma reesei) to total reducing sugars (TRSs), which was further fermented for bioethanol production using yeast strains. Different time (30, 60, 90 and 120min), concentrations of NaOH (0.5%, 1%, 1.5% and 2%) as well as temperatures (100, 110 and 120°C) were used for pretreatment study. At 120°C, approximately more than 50% of delignification was observed. Moreover, subsequent enzymatic saccharification contributed 350mgg−1 dry biomass of total reducing sugar (TRS) production. Interestingly, TRS was approx. fivefold higher than enzymatic saccharification of acid pretreated biomass (69.08mgg−1) as reported previously (Kataria et al., 2011) and fermentation of enzymatic hydrolysate using microbes resulted in the 0.44–0.46gg−1 ethanol yield which is a high yield when compared to the other existing literature. Another advantage of alkali pre-treatment was without production of toxic compounds in comparison to acid pre-treatment method. In conclusion, Kans grass was shown as potential feedstock for biofuel production via alkali and enzymatic saccharification in contrast to acid pre-treatment.

Production of Bioethanol from Carrot Pomace Using the Thermotolerant Yeast Kluyveromyces marxianus

Carrot pomace, a major agricultural waste from the juice industry, was used as a feedstock for bioethanol production by fermentation with the thermotolerant yeast Kluyveromyces marxianus. Treatment of the carrot pomace with AccelleraseTM 1000 and pectinase at 50 °C for 84 h, resulted in conversion of 42% of its mass to fermentable sugars, mainly glucose, fructose, and sucrose. Simultaneous saccharification and fermentation (SSF) at 42 °C was performed on 10% (w/v) carrot pomace; the concentration of ethanol reached 18 g/L and the yield of ethanol from carrot pomace was 0.18 g/g. The highest ethanol concentration of 37 g/L was observed with an additional charge of 10% supplemented to the original 10% of carrot pomace after 12 h; the corresponding yield was 0.185 g/g. Our results clearly demonstrated the potential of combining a SSF process with thermotolerant yeast for the production of bioethanol using carrot pomace as a feedstock.

Use of tropical maize for bioethanol production

Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25-2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1 % (v/v) to 15.6 % (v/v), equivalent to 90.3-92.2 % of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry.

Surface Modified Reverse Osmosis and Nano-Filtration Membranes for the Production of Biorenewable Fuels and Chemicals.

ABSTRACTThe Renewable Fuels Standard (RFS) and Energy Independence and Security Act of 2007 (EISA) mandated that 36 billion gallons of biofuels should be blended into transportation fuel by 2022. Implementing this will help reduce greenhouse gas emissions, reduce petroleum imports and encourage the development and expansion of US renewable fuels sector within rural America. Of the 36 billion gallons of biofuels, 16 billion gallons is expected to be from lignocellulosic biomass such as trees and grasses. The Black Hills of South Dakota is rich in ponderosa pine. This feedstock for bioethanol production, which is widely available due to recent pine beetle infestation, will not only add to the RFS requirement, it will also have a positive impact on rural economies in South Dakota. From the wood chips of pine, after acid pretreatment and enzymatic hydrolysis, the fermentable sugars obtained are relatively dilute in concentration (∼20-30 g/L). Hence, within a biorefinery, to increase the fermentation efficiency and decrease downstream processing cost of the biofuels, concentrating the sugars can be beneficial. In this study, Reverse Osmosis (RO) and Nanofiltration (NF) membranes were tested with complex lignocellulosic hydrolysate samples for their ability to concentrate sugars prior to fermentation. Fouling analysis and membrane characterization for both RO and NF membranes were performed by SEM, AFM, BET, contact angle and FTIR spectroscopy. Efficiency of membranes for their ability to separate fermentation inhibitors (e.g., organic and mineral acids, furans and phenolic compounds) from sugars, while simultaneously concentrating the sugars was studied to make the bio-ethanol production process cost and energy efficient. Three commercial nanofiltration membranes GE-R, TS40 and SR100 showed very promising results. GE-R concentrated sugars to more than 2.5 fold in the retentate, and simultaneously separated more than 50% of the inhibitory components into permeate. These results will increase the fermentation efficiency and reduce downstream purification costs of the produced fuel.

Anaerobic treatment of lignocellulosic material to co-produce methane and digested fiber for ethanol biorefining

Five different ratios of corn stover to swine manure were investigated to evaluate the performance of anaerobic digestion and the quality of anaerobically digested fiber (AD fiber) as a feedstock for bioethanol production. The stover-to-manure ratio of 40:60 generated 364L biogas and 797g AD fiber per kg of dry raw feedstock daily. The AD fibers after digestion were pretreated and hydrolyzed to release sugars for ethanol fermentation. The stover-to-manure ratio of 40:60 was able to produce 152g methane and 50g ethanol per kg of dry raw feedstock. The net energy generated from the ratio 40:60 was 5.5MJkg−1 dry raw feed, which was an 18% increase on net energy output compared to the other ratios and proved to be most beneficial for a biorefinery.