Butanol Concentration Research Articles

Development of co-culture yeast fermentation for efficient production of biobutanol from rice straw: A useful insight in valorization of agro industrial residues

Escalating environmental concerns and petroleum demands leads into the present study. In this investigation delignification of rice straw was optimized by NaOH and H2SO4 pretreatment using L16 Taguchi orthogonal array. NaOH pretreatment revealed higher delignification as compared to H2SO4 and; further subjected to separate enzymatic hydrolysis and co-fermentation (SHCF) using RSM as the SHCF demonstrated a maximum glucose and xylose yield of 575 and 205 mg/g. Further, butanol concentration of 4.32 g/L was achieved from 20 g/L of sugar loadings by co-culture of Saccharomyces cerevisiae and Pichia sp. at 72 h of incubation time which was 79.25% higher as compared to monocultures of Pichia sp. Scale-up experiments with higher sugar loadings (90 g/L) demonstrated a butanol concentration of 13.3 g/L. The release of amino acids in co-culture and monoculture systems demonstrated that the addition of S. cerevisiae promoted the butanol synthesis pathway which led to higher butanol concentration.

Influence of acetic and butyric acid and gas release modes on immobilized Clostridium acetobutylicum (DSMZ 792) in repeated batch experiments

The effects of supplementation of standard media with metabolic intermediates (2 g/L butyric acid, 2 g/L butyric acid + 1.5 g/L acetic acid) on butanol and hydrogen production/yield were evaluated. Fermentations were conducted with immobilized Clostridium acetobutylicum (DSMZ 792). Additionally, the influence of gas release modes (constant gas release vs. interval gas release) was tested in all setups to evaluate butanol and hydrogen production and yields. Fermentations were implemented in repeated batch mode (48 h, 37 °C, 100 rpm). Overpressure conditions had a negative impact on volumetric hydrogen production and hydrogen yield and a positive impact on butanol yield. Supplementation significantly increased the butanol concentrations in constant gas release mode, by 23.6%. When interval gas mode was applied in the supplemented fermentations, the butanol concentrations decreased by 8.4% when butyric acid was fed, and reached similar concentrations when both acids were added. The highest butanol concentration and volumetric butanol production rate of 9.6 ± 0.6 g/L and 0.2 ± 0.0 g/L*h, respectively, were reached with butyric acid supplementation and constant gas release mode. The highest volumetric hydrogen production was reached with the constant gas release mode in fermentations conducted with the addition of both acids, and reached 165 ± 9 mL/L*h.

Process optimization for conversion of Waste Banana peels to biobutanol by A yeast Co-Culture fermentation system

In the present investigation, sodium hydroxide (NaOH) and sulfuric acid (H2SO4) pretreatment were conducted using response surface methodology (RSM) technique for maximum cellulose exposure and delignification of banana peel (BP) biomass. H2SO4 pretreatment revealed higher cellulose exposure (585.2 mg/g of biomass) as compared to NaOH pretreatment. H2SO4 pre-treated banana peel (PBP) was further subjected to separate enzymatic hydrolysis and co-fermentation (SHCF) using L16 Taguchi orthogonal array design. SHCF demonstrated a maximum glucose and xylose yield of 677.3 and 165.1 mg/g of PBP respectively. Further, higher butanol titers of 7.4 g/L were achieved from 20 g/L of sugar loadings by co-culture of Saccharomyces cerevisiae and Pichia sp. at 72 h of incubation time which was 89.1% and 75.67% higher as compared to monocultures of S cerevisiae and Pichia sp. respectively. Scale-up experiments with higher sugar loadings (90 g/L) demonstrated lower butanol concentrations of 15.7 g/L with total butanol productivity of 0.2 g/L/h. The overall energy consumption for 1 g of fuel-grade butanol from 20 g/L (shake flask) and 90 g/L (fermenter) of reducing sugar loadings was 138.1 KJ and 85.7 KJ respectively.

Formulation of Bio-Based Washing Agent and Its Application for Removal of Petroleum Hydrocarbons From Drill Cuttings Before Bioremediation.

Drill cuttings from petroleum exploration and production sites can cause diverse environmental problems. Total petroleum hydrocarbons (TPHs) are a major pollutant from the use of polyolefin-based mud. As an alternative to incineration, this study investigated the application of surfactant-enhanced washing technology prior to bioremediation. The washing step was necessary because the initial TPH concentrations were quite high at approximately 15% (w/w). Washing agents were formulated by varying the concentration of lipopeptide biosurfactant (in foamate or cell-free broth), Dehydol LS7TH (fatty alcohol ethoxylate 7EO, oleochemical surfactant) and butanol (as a lipophilic linker) at different salinities. The most efficient formula produced a Winsor Type I microemulsion (oil-in-water microemulsion) with polyolefin and contained only 20% (v/v) foamate and 2% (v/v) Dehydol LS7TH in water. Due to the synergistic behavior between the anionic lipopeptides and non-ionic Dehydol LS7TH, the formula efficiently removed 92% of the TPHs from the drill cuttings when applied in a jar test. To reduce the cost, the concentrations of each surfactant should be reduced; thus, the formula was optimized by the simplex lattice mixture design. In addition, cell-free broth, at a pH of 10, containing 3.0 g/L lipopeptides was applied instead of foamate because it was easy to prepare. The optimized formula removed 81.2% of the TPHs and contained 72.0% cell-free broth and 1.4% Dehydol LS7TH in water. A 20-kg soil washing system was later tested where the petroleum removal efficiency decreased to 70.7% due to polyolefin redeposition during separation of the washing solution. The remaining TPHs (4.5%) in the washed drilled cuttings were further degraded by a mixture of Marinobacter salsuginis RK5, Microbacterium saccharophilum RK15 and Gordonia amicalis JC11. To promote TPH biodegradation, biochar and fertilizer were applied along with bacterial consortia in a microcosm experiment. After 49-day incubation, the TPHs were reduced to 0.9% by both physical and biological mechanisms, while the TPHs in the unamended samples remained unaffected. With the use of the formulated bio-based washing agent and bioremediation approach, the on-site treatment of drill cuttings could be conducted with an acceptable cost and low environmental impacts.

Comparison of simultaneous saccharification and fermentation and separate hydrolysis and fermentation processes for butanol production from rice straw

Rice straw (RS) is one of the lignocellulosic wastes with the highest global production. The main objective of this study was to maximise the butanol production by Clostridium beijerinckii DSM 6422 from RS pretreated by microwave-assisted hydrothermolysis. Two different fermentation strategies were compared: separate hydrolysis and fermentation (SHF, two-step process) and simultaneous saccharification and fermentation (SSF, one-step process). In parallel, the variables that significantly affected the butanol production were screened by using fractional factorial designs. Butanol concentration and productivity at 48 h were, respectively, 8% and 173% higher in SSF than in SHF. A one-step process was more efficient than a two-step process, especially considering the time savings derived from much higher productivity. From these results, SSF was further optimised by response surface methodology with central composite design over the key factors on the butanol production at 48 h: initial pH, enzyme loading and yeast extract concentration. The optimum point yielded a butanol productivity of 0.114 g L-1h−1, with a butanol-biomass ratio of 51 g kg−1 of raw RS (ABE-biomass ratio of 77.0 g kg−1 of raw RS). The parameter with the greatest effect was enzyme loading, with an optimal value of 13.5 FPU g-dw-1. This study showed that microwave-processed RS has great potential as a substrate for the butanol production from ABE fermentation when combining process stages by SSF.

Bioprocess intensification for isopropanol, butanol and ethanol (IBE) production by fermentation from sugarcane and sweet sorghum juices through a gas stripping-pervaporation recovery process

Butanol and isopropanol are important commodity chemicals with a variety of applications. One of the main obstacles for biobutanol production by IBE (isopropanol–butanol–ethanol) fermentation is the intensive energy consumption for product recovery by conventional distillation due to low butanol titer in fermentation broth caused by butanol toxicity to cells. In the present study, butanol production by batch IBE fermentation coupled to an in situ gas stripping-pervaporation process to recover the butanol is proposed using Clostridium beijerinckii DSM 6423 and a mixture of sugarcane-sweet sorghum juices as substrate. Gas stripping was used to continuously remove butanol from the fermentation broth, followed with pervaporation to further concentrate butanol. The strategy used allows alleviating butanol inhibition and to recuperate a condensate containing high butanol concentration (559 g/L). A kinetic model describing butanol production by IBE fermentation was developed. Kinetic parameters and experimental data were used to estimate the energy consumption of the sugarcane-sweet sorghum IBE production process. It was found that although the IBE production process showed less energy consumption (15%) than the butanol production process by ABE (acetone-butanol-ethanol) fermentation, a substantial improvement is still necessary for the process to be energetically/economically attractive.

Synthesis of Butyl-β-D-Galactoside in the Ternary System: Acetone/1-Butanol/Aqueous Solution.

The enzymatic synthesis of short-tailed alkyl glucosides is generally carried out in an aqueous-organic biphasic reaction medium with a rather low fatty alcohol concentration in the aqueous phase (where the synthesis occurs). Thus, hydrolytic reactions have a significant impact on the synthesis performance. Given this background, the use of acetone as cosolvent was studied for the synthesis of butyl-β-galactoside with Aspergillus oryzae β-galactosidase. The liquid–liquid equilibrium of the reaction mixture components (acetone/1-butanol/aqueous solution) was determined and the single- and two-phase regions were defined at 30, 40, and 50°C. It was observed that the liquid–liquid equilibrium of the ternary system acetone/1-butanol/water differs significantly from the one obtained using an aqueous solution (50 mM McIlvaine buffer pH 4.5; 5 g L–1) instead of water. This is mainly because of the salting-out effect of the buffer; nevertheless, the presence of lactose also altered the equilibrium. Having this in mind, the effects of temperature (30 and 50°C) and reaction mixture composition were assessed. Three general conditions were evaluated: single-phase ternary system (30% acetone), two-phase ternary system (10% acetone) and two-phase binary system (0% acetone). Acetone had a deleterious effect on enzyme stability at 50°C, leading to low reaction yields. However, no enzyme deactivation was detected at 30°C. Moreover, a reaction yield of 0.98 mol mol–1 was attained in the 30/50/20% (w/w) mixture of acetone/1-butanol/aqueous solution. This very high yield can be explained by the huge increase in the concentration of 1-butanol and the reduction of water activity. The synthesis was carried out using also the β-galactosidase immobilized in glyoxal-agarose and amino-glyoxal-agarose, and by aggregation and crosslinking. In the case of agarose-derived catalysts, two average particle diameters were assessed to evaluate the presence of internal mass transfer limitations. Best yield (0.88 mol mol–1) was obtained with glyoxal-agarose derivatives and the particle size had non-effect on yield. The chemical structure of butyl-β-galactoside was determined by NMR and FT-IR.

Mechanism for sonochemical reduction of Au(III) in aqueous butanol solution under Ar based on the analysis of gaseous and water-soluble products

When an aqueous Au(III) solution containing 1-butanol was sonicated under Ar, Au(III) was reduced to Au(0) to form Au particles. This is because various reducing species are formed during sonication, but the reactivity of these species has not yet been evaluated in detail. Therefore, in this study, we analyzed the effects of Au(III) on the rates of the formation of gaseous and water-soluble compounds (CH4, C2H6, C2H4, C2H2, CO, CO2, H2, H2O2, and aldehydes), and the rate of Au(III) reduction as a function of 1-butanol concentration. The following facts were recognized: 1) for Au(III) reduction, the contribution of the radicals formed by the pyrolysis of 1-butanol was higher than that of the secondary radicals formed by the abstraction reactions of 1-butanol with ·OH, 2) ·CH3 and CO acted as reductants, 3) the contribution of ·H to Au(III) reduction was small in the presence of 1-butanol, 4) aldehydes and H2 did not act as reductants, and 5) the types of species that reduced Au(III) changed with 1-butanol concentration.

BIOBUTANOL PRODUCTION USING FED-BATCH HIGH CELL DENSITY EXTRACTIVE FERMENTATION

Butanol, as a product with specific toxicity for its producer, is necessary to be maintained in low concentration during fermentation. In-situ integrated recovery using extensive volume extraction was used in high cell density fermentation in order to prevent the lag phase in the prime condition. Clostridium saccharoperbutylacetonicum N1-4 ATCC 13564 was employed to ferment glucose in extractive fermentation with oleyl alcohol as extractant. As the results of fed-batch cultures using high cell density with different extractant to broth volume ratios (Ve/Vb), 0.8 g/l butanol concentration in the broth was maintained with a ratio of 10, which was much lower than 4.4 g/l with the ratio of 0.5. Besides, the Ve/Vb ratio of 10 demonstrated 2.7-fold higher total butanol concentration (28 g/l) than that 11 g/l obtained with a Ve/Vb ratio of 0.5. These results indicated that larger Ve/Vb improved total butanol concentration by reducing butanol toxicity in broth.

Solvent extraction of butanol from synthetic solution and fermentation broth: Batch and continuous studies

Product recovery is one of the essential finishing steps to any commercial fermentation process. In acetone-butanol-ethanol (ABE) fermentation, butanol recovery is quite tedious mainly due to dilute product and multiple byproduct formation in complex media. Among different recovery methods, extraction has attracted considerable attention in biofuel recovery owing to its high selectivity, low energy consumption, and ease of operation. In present work, the butanol extraction performance from synthetic solvent mixture containing ABE was tested in batch and continuous operations using 20% (v/v) decanol in oleyl alcohol. The optimized extraction conditions were then validated using actual fermentation broth to confirm effectiveness of the extraction operation. The distribution coefficient (Kd) and batch extraction efficiency (E) were in the range of 5.60–9.80 and 87.70–86.90% for fermentation broth and synthetic solution, respectively for a given initial concentration of butanol in the aqueous phase. Further, E was relatively improved by supplementing different inorganic salts. Sodium hydroxide (5%, w/v) was highly effective to recover butanol from fermentation broth (E ~ 97.70%) with Kd of 33.10. Besides, the continuous counter current extraction of butanol in a packed column was performed. The volumetric mass transfer coefficient (kLa) was estimated to be 0.025 1/min at an optimized superficial velocity of the aqueous phase (0.28 cm/min) and sodium hydroxide concentration (5%, w/v). Height of the extraction column was estimated to be 28.32 cm using height of transfer unit (HTU) and number of transfer unit (NTU) concept for extraction efficiency of 97.20%. Overall, the present study has demonstrated an enhanced extraction efficiency of butanol from fermentation broth.

Analysis of Combustion Process of Protective Coating Paints

Structural elements in buildings exposed to high temperature may lose their original stability. Application of steel structures has several advantages; however, deflection under exposure to high temperatures may be a potential obstacle. Therefore, the aim of the study was to determine how temperature affects decomposition of protective paints applied in the construction. A dedicated installation for the analysis of the combustion process of protective coating paints in a laboratory scale was prepared. The experimental device consisted of the following parts: top-loading furnace connected to the gas conditioner, the LAT MG-2 gas mixer, and portable gas analyzer GASMET DX-4010. The following type of the protective powder coating paints were analyzed: alkyd and polyurethane. The obtained results indicated that during thermal decomposition of paints, formaldehyde, benzene, heptane, and butanol were released, however in different concentrations. Moreover, decomposition temperature affected the type and amount of released gas mixture components. With increasing temperature, increased release of formaldehyde and benzene was noticed, while the concentration of butanol and heptane decreased. Finally, the product of thermal decomposition emitted in the highest concentration was formaldehyde, which can cause irritation and sensitization in humans.

Applying Odor Preconcentrator for Enhancing Human Olfaction: Feasibility Study

Introduction The human sense of smell plays important roles in various scenes in everyday life although we are unconscious of the importance in most cases. For example, olfaction provides an alert that lets us notice dangers or risks such as a fire and rotten food. Savory food smells and comfort flower fragrances make our lives richer. However, it is known that the human olfaction deteriorates with our age [1]. There is no device that can improve the deteriorated olfaction whereas impaired vision can be improved using eyeglasses and a hearing aids can improve our audition. The aim of this research project is to develop an olfactory amplifier for humans [2,3]. In chemical analysis, preconcentrators are frequently used to analyze faint chemical substances [4]. We propose to apply this technique to enhance the sensitivity of human olfaction. In the proposed olfactory amplifier system, airborne odor molecules are collected into adsorbent, as in the preconcentrator. When a sufficient amount of odor molecules are collected, the adsorbent is heated to a high temperature to thermally desorb the collected molecules in a short time. The concentrated odors are thus generated. Here we report our new device made with a monolithic silica adsorbent. Results of odor concentration experiments and a sensory test are presented to show that the device can generate a concentrated smell from a faint smell. Method The schematic diagram of our new device that uses a disc-shaped monolithic silica (MonoTrap DSC18, GL Science) as an adsorbent is shown in Figure 1. The cross section of the device is shown in Figure 2. The diameter and thickness of the monolithic silica disk are 10 mm and 1 mm, respectively. This adsorbent is housed in a flow cell which was made by putting a rubber sheet with a hole in the middle between an acrylic plate and a printed circuit board. A meander heater made on the printed circuit board is used for thermally desorbing the collected odor molecules from the monolithic silica disk. Five stainless tubes are attached to the flow cell. Air is sent into the flow cell through the center tube, and is exhausted from the four outer tubes.In the odor concentration experiment, 1.2 ppm 1-butanol vapor packed in a sampling bag was sent into the flow cell at a flow rate of 0.8 L/min for 10 min. The collected gas was desorbed by heating up the monolithic silica to 200 degrees centigrade. Clean air was sent to the flow cell at a flow rate of 20 mL/min to take the concentrated gas out from the flow cell. The concentration of the butanol gas presented from the device was measured using a semiconductor gas sensor (TGS2620, Figaro Engineering) In the sensory test, we prepared liquid apple flavor consisting of nine components. The flavor was diluted by 100 times using liquid paraffin. Eight subjects participated in the sensory test. Each subject was asked to sniff the diluted apple flavor and compare the smell with the smell of the concentrated vapor presented from the odor amplifier device. Results and Discussions Figure 3 shows the response curve of the gas sensor which was exposed to the vapor coming out from the odor amplifier device. The sensor response is defined as the ratio of the sensor resistance in gas to that in air. Its value decreases with the gas concentration. At 20 s from the start of recording the sensor response, the heating was turned on. The pump was activated after 4 s delay from the activation of the heater. The concentration factor calculated from the maximum butanol concentration detected by the gas sensor was 13.1. When the delay was reduced to 0 s, the concentration factor was slightly decreased. Table 1 shows the result of the sensory test. All subjects answered that the vapor presented from the amplifier device had a stronger smell and that the difference in the smell intensity was significant. Seven out of eight subjects even told us that they perceived no smell from the diluted liquid apple flavor. This resulted in their answers to the third question: most subjects told us that the original and concentrated smells were different because they were unable to perceive the original smell. These results show that a sufficient odor amplification effect can be obtained by a concentration factor of approximately 10. Future work will be addressed to enable quicker presentation of concentrated odors. This work was supported in part by JSPS KAKENHI Grant Numbers 19K14947 and 19H02103, and Research Grant from the Okawa Foundation for Information and Telecommunications.

A novel integrated process to convert cellulose and hemicellulose in rice straw to biobutanol

A novel integrated process was established in this study to produce butanol from rice straw. In the first pretreatment, an alternative NaOH/Urea preatment operated at −12 oC efficiently removed 10.9 g lignin and preserved 91.54% cellulose and hemicellulose in 100 g rice straw. Subsequently, crude cellulase produced from Trichoderma viride was used to convert pretreated rice straw to mono-sugars for fermentation. The yields of glucose, xylose and arabiose obtained from 100 g rice straw were 31 g, 13.4 g and 0.48 g, respectively, resulting in a 69.45% saccharification efficiency of crude enzyme. Finally, to alleviate the carbon catabolite repression (CCR) and enhance butanol production, the coculture system of Clostridium beijerinckii and Saccharomyces cerevisiae was applied. Compared to monoculture of C. beijerinckii F-6, more sugars were consumed, especially the reduction rate of xylose reached to 81.87%, 32.99% higher than that in monoculture system. With more substrate facilitied into metabolism, the butanol concentration reached to 10.62 g/L corresponding to 0.28 g/g substrate, 115.38% higher than that in monoculture system. Overall, this integrated process was a low-energy consumption and efficient method for butanol production from rice straw.

A Highly Water-Stable meta-Carborane-Based Copper Metal-Organic Framework for Efficient High-Temperature Butanol Separation.

Biofuels are considered sustainable and renewable alternatives to conventional fossil fuels. Biobutanol has recently emerged as an attractive option compared to bioethanol and biodiesel, but a significant challenge in its production lies in the separation stage. The current industrial process for the production of biobutanol includes the ABE (acetone-butanol-ethanol) fermentation process from biomass; the resulting fermentation broth has a butanol concentration of no more than 2 wt% (the rest is essentially water). Therefore, the development of a cost-effective process for separation of butanol from dilute aqueous solutions is highly desirable. The use of porous materials for the adsorptive separation of ABE mixtures is considered a highly promising route, as these materials can potentially have high affinities for alcohols and low affinities for water. To date, zeolites have been tested toward this separation, but their hydrophilic nature makes them highly incompetent for this application. The use of metal-organic frameworks (MOFs) is an apparent solution; however, their low hydrolytic stabilities hinder their implementation in this application. So far, a few nanoporous zeolitic imidazolate frameworks (ZIFs) have shown excellent potential for butanol separation due to their good hydrolytic and thermal stabilities. Herein, we present a novel, porous, and hydrophobic MOF based on copper ions and carborane-carboxylate ligands, mCB-MOF-1, for butanol recovery. mCB-MOF-1 exhibits excellent stability when immersed in organic solvents, water at 90 °C for at least two months, and acidic and basic aqueous solutions. We found that, like ZIF-8, mCB-MOF-1 is non-porous to water (type II isotherm), but it has higher affinity for ethanol, butanol, and acetone compared to ZIF-8, as suggested by the shape of the vapor isotherms at the crucial low-pressure region. This is reflected in the separation of a realistic ABE mixture in which mCB-MOF-1 recovers butanol more efficiently compared to ZIF-8 at 333 K.

Inductively coupled plasma reactive ion etching of copper thin films using ethylenediamine/butanol/Ar plasma

The dry etching of copper thin films patterned with SiO2 hard masks was performed using an ethylenediamine (EDA)/butanol/Ar gas mixture. Ethylenediamine is an organic chelator that served as the main etching gas and butanol was used as an additive gas. As the concentrations of EDA and butanol in EDA/Ar and butanol/Ar increased, respectively, the etch rate of copper thin films decreased. The etch rate in EDA was less than that in butanol. However, a good etch profile of copper thin films was obtained with high EDA concentration in the EDA/Ar gas mixture, whereas high etch selectivity of copper was achieved from the butanol/Ar gas mixture. In the EDA/butanol/Ar gas mixture, the optimal ratio of EDA to butanol was investigated to increase the etch rate and improve the etch profile. The optical emission spectroscopy indicates that the main species in EDA were [CN] and [H], whereas in butanol, [H] was the main substance. The X-ray photoelectron spectroscopy reveals that copper reacted with [CN], [H], and [O] to form copper compounds that could be desorbed from the film surface by the sputtering of ions. The EDA/butanol/Ar gas mixture can be a good etch gas to dry-etch copper thin films.

Efficient use of brewer's spent grain hydrolysates in ABE fermentation by Clostridium beijerinkii. Effect of high solid loads in the enzymatic hydrolysis

AbstractBACKGROUNDBrewer's spent grain (BSG) has been employed to investigate the use of hemicellulosic and cellulosic sugars in Acetone‐Butanol‐Ethanol (ABE) fermentation. A dilute‐acid pretreatment was conducted, followed by enzymatic hydrolysis at different solid loads (10–15–20% DM) and ABE fermentation by Clostridium beijerinckii DSM 6422. Operation at solid loadings higher than 15% DM (60.1 g L−1 of total sugars, 1.03 g phenolic/L) makes the development of a detoxification step necessary.RESULTSThe higher butanol and ABE concentrations for the pretreatment liquor were obtained when activated carbon was used as the detoxification agent (11.5 ± 0.1 g L−1 butanol, 16.2 ± 0.2 g L−1 ABE, 95.1% sugar uptake), whereas the sequential activated carbon and overliming detoxification strategy was the most effective for 15% DM enzymatic hydrolysates (11.6 ± 0.2 g L−1 butanol, 18.3 ± 0.3 g L−1 ABE, 89.6% sugar uptake).CONCLUSIONThe overall yield, taking into account the pretreatment liquor and enzymatic hydrolysate, was 99.8 g butanol/kg BSG and 146.5 g ABE/kg BSG, improving the results without detoxification by more than 40%. © 2020 Society of Chemical Industry

Compositional variability of food wastes and its effects on acetone-butanol-ethanol fermentation

Converting food waste into butanol via acetone, butanol, and ethanol (ABE) fermentation provides the potential to recover energy and value-added chemicals from food waste. However, the high variability of food waste compositions has hindered the consistency and predictability of butanol production, impeding the development of a robust industrial fermentation process. This study characterized the compositional variation of collected food wastes and determined correlations between food waste compositional attributes and butanol yields for a better prediction of food waste fermentation with Clostridium. The total sugar, starch, fiber, crude protein, fat and ash contents (on dry basis) in the food waste samples were in a range of 0.5–53.5%, 0–25.2%, 0.6–26.9%, 5.5–21.5%, 0.1–37.9%, and 1.4–13.7%, respectively. The high variability of food waste composition resulted in a wide range (3.5–11.5 g/L) of butanol concentrations with an average of 8.2 g/L. Pearson’s correlation analysis revealed that the butanol concentrations were strongly and positively correlated with equivalent glucose and starch contents in food waste, strongly and negatively correlated with fiber content, and weakly correlated with total sugar, protein, fat, and ash contents. The regression models constructed based on equivalent glucose and fiber contents reasonably predicted the butanol concentration, with the R2 of 0.80. Our study investigated the variability of food waste composition and, for the first time, unveiled relationships between food waste compositional attributes and fermentation yields, contributing to a greater understanding of food waste fermentation, which, in turn, assists in developing new strategies for increased consistency and predictability of food waste fermentation.

Selective Separation of 1-Butanol from Aqueous Solution through Pervaporation Using PTSMP-Silica Nano Hybrid Membrane.

In this work, a poly(1-trimethylsilyl-1-propyne) (PTMSP) mixed-matrix membrane was fabricated for the selective removal of 1-butanol from aqueous solutions through pervaporation. Silica nanoparticles (SNPs), which were surface-modified with surfactant hexadecyltrimethylammonium bromide (CTAB), were incorporated into the structure of the membrane. The modified membrane was characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), contact angle measurements, and scanning electron microscope (SEM) analysis. It was found that the surface hydrophobicity of the membrane was improved when compared to neat PTMSP by contact angle measurement. It was confirmed by SEM analysis that a uniform distribution of surface-modified SNPs throughout the PTMSP membrane was achieved. The thermogravimetric analysis detected the thermal degradation of the modified PTMSP at 370 °C, which is comparable to neat PTMSP. The pervaporation measurements showed a maximum separation factor of 126 at 63 °C for 1.5 w/w% 1-butanol in the feed. The maximum total flux of approximately 1.74 mg·cm−2·min−1 was observed with the highest inspected temperature of 63 °C and at the 1-butanol concentration in the feed 4.5 w/w%. The pervaporation transients showed that the addition of the surface-modified SNPs significantly enhanced the diffusivity of 1-butanol in the composite compared to the neat PTMSP membrane. This improvement was attributed to the influence of the well-dispersed SNPs in the PTMSP matrix, which introduced an additional path for diffusivity.

Thermostable, Solvent, Surfactant, Reducing Agent and Chelator Resistant α-Amylase from Bacillus Strain IBT108: A Suitable Candidate Enables One-Step Fermentation of Waste Potato for High Butanol and Hydrogen Production

α-Amylase is the major biocatalyst involved in saccharification process of starch-based biofuel production. Most of the α-amylases reported in literature are not stable and catalytically active in presence of metabolites (biosolvents, and bioacids), and other media components such as salts and reducing agents, hence starch-based biofuels are produced by two-step process of separate hydrolysis by α-amylase, and later the fermentation of biofuel production. Finding new α-amylase with special properties can assist to integrate the process of saccharification and biofuel fermentation. We report a new α-amylase produced from wild type Bacillus strain IBT108. This α-amylase (10.5 U/ml) can be produced from wheat bran (5%) based medium. It can be purified by diethylaminoethyl weak anion exchange-based fast protein liquid chromatography. Purified α-amylase has molecular mass of 68 kDa with a high specific activity (734.8 U/mg), and significant Vmax (1428.6 U/mg) and Km (2.8 mg/ml). Protein fingerprinting analysis reveals that it is a unique member of super-families of AmyAc and MaltAmyC which can act on both α-1,4 and α-1,6-glycosidic linkages of starch. It shows optimal activity at pH 7 and 70 °C, retains 72–92% of its activity in acidic pH range between 4 and 6.5, and stable at 60 °C for 2 h. Notably, it is resistant to 5 mM concentration of urea, dithiothreitol, β-mercaptoethanol, surfactants and EDTA, also shows > 70% of its activity in presence of 1 M solvents. Consequently, adding this α-amylase (2.5–3 U/ml) assists Clostridia to effectively utilize 375 g/l waste potato, and produce high concentration of butanol (20.41–23.74 g/l) and hydrogen (3.20–4.38 l/l).

Selective evaporation of a butanol/water droplet by microwave irradiation, a step toward economizing biobutanol production

The separation step is a constraint in biobutanol production, due to high energy consumption of the current techniques. This study explores a new separation method via applying microwave irradiation. Butanol/water droplet was monitored during exposure to microwave irradiation at different power rates. The surface tension, droplet volume, and temperature were scrutinized during and after exposure to microwave irradiation. The data obtained indicated that the microwave-induced evaporation rates of alcohols were much higher than that of water. Consequently, the vaporized phase contained a much higher alcohol content than the liquid phase. In particular, butanol concentration in the aqueous phase could be reduced to similar to 0.1 wt.%, which was more effective than the theoretical limit via the boiling process. The method is an attractive option to complement the fermentation process, which produces a low butanol concentration solution. This development could potentially lead to a more efficient pathway for biobutanol production. (C) 2020 BRTeam. All rights reserved.