Acetone-butanol-ethanol Productivity Research Articles

PDMS/ceramic composite membrane for pervaporation separation of acetone–butanol–ethanol (ABE) aqueous solutions and its application in intensification of ABE fermentation process

Pervaporation (PV) has attracted increasing attention because of its potential application in bio-butanol recovery from fermentation process. In this work, PDMS/ceramic composite membrane was employed for PV separation of acetone–butanol–ethanol (ABE) aqueous solutions. The influence of coupling effect on the molecular transport during the PV process was systematically investigated. The separation performance and transport phenomena of ABE molecules were discussed based on the analysis and calculation of physicochemical properties such as solubility parameter, polarity parameter, interaction parameter, activity coefficient. The results suggested that the ABE separation factor was mainly determined by the intrinsic solubility parameter and driving force. Coupling effect in the ABE multicomponent system was closely related to the interaction parameters between components themselves and between component and membrane. Also, the PDMS membrane was integrated with ABE fermentation to construct an efficient intensification process. It was found that the rate matching of fermentation and in situ removal could improve the ABE productivity by 2 times.

An integrated in situ extraction-gas stripping process for Acetone–Butanol–Ethanol (ABE) fermentation

A novel integrated in situ extraction-gas stripping process (Process 3 in this study) is proposed for running batch Acetone–Butanol–Ethanol (ABE) fermentation. The process involves two butanol separation processes in which butanol is first extracted by oleyl alcohol during ABE fermentation and gas stripping is carried out on butanol in the oleyl alcohol phase at the same time. The butanol productivity and yield of Process 3 is 0.28±0.01g/L/h and 0.226±0.001g-butanol/g-glucose. The ABE productivity and yield are 0.46±0.01g/L/h and 0.374±0.002g-ABE/g-glucose. Glucose utilization was 97% and initial glucose consumption was 121±2g/L. Butanol and ABE concentrations of 93–113 and 166–204g/L in the condensate can be achieved. This study demonstrates that Process 3 as described here enhances ABE fermentation and also results in the production of high purity solvents.

Sweet sorghum bagasse as an immobilized carrier for ABE fermentation by using Clostridium acetobutylicum ABE 1201

Sweet sorghum bagasse as an immobilized carrier for ABE fermentation by usingClostridium acetobutylicumABE 1201.

Organosolv pretreatment of rice straw for efficient acetone, butanol, and ethanol production

Acetone-butanol-ethanol (ABE) was produced from rice straw using a process containing ethanol organosolv pretreatment, enzymatic hydrolysis, and fermentation by Clostridium acetobutylicum bacterium. Pretreatment of the straw with 75% (v/v) aqueous ethanol containing 1% w/w sulfuric acid at 150 °C for 60 min resulted in the highest total sugar concentration of 31 g/L in the enzymatic hydrolysis. However, the highest ABE concentration and productivity (10.5 g/L and 0.20 g/Lh, respectively) were obtained from the straw pretreated at 180 °C for 30 min. Enzymatic hydrolysis of the straw pretreated at 180 °C for 30 min with 5% solid loading resulted in glucose yield of 46.2%, which was then fermented to 80.3 g butanol, 21.1 g acetone, and 22.5 g ethanol, the highest overall yield of ABE production. Thus, the organosolv pretreatment can be applied for efficient production of the solvents from rice straw.

ABE production from yellow poplar through alkaline pre-hydrolysis, enzymatic saccharification, and fermentation

ABE (acetone-butanol-ethanol) was produced through alkaline pre-hydrolysis, enzymatic saccharification, and fermentation using yellow poplar as a raw material. In alkaline pre-hydrolysis, 51.1% of the biomass remained as a residue. In the main woody components, the degrees of lignin and xylan removal were 94.3 and 62.0%, respectively. A yield of 80.9% for cellulose-to-glucose and 81.2% for xylan-to-xylose were obtained by enzymatic hydrolysis. The sugar composition of enzymatic hydrolysate was 95.1 g/L of glucose and 21.4 g/L of xylose. The enzymatic hydrolysate also contained 0.5 g/L of acetic acid and 0.5 g/L of total phenolics. Furfural and 5-hydroxymethylfurfural (5-HMF) were not detected in this hydrolysate. The yellow poplar hydrolysate (YPH) from enzymatic saccharification was used for the production of ABE using Clostridium acetobutylicum and C. beijerinckii. In YPH fermentation, C. acetobutylicum produced 18.1 g/L total ABE (productivity 0.38 g/L h, and yield 0.42), and C. beijerinckii produced 12.1 g/L (productivity 0.25 g/L h, and yield 0.37). Although the ABE productivity by C. beijerinckii was slightly low, the general performance of ABE fermentation in YPH was similar to or higher than those reported previously. Therefore, alkaline pre-hydrolysis could be a very effective pretreatment step prior to enzymatic hydrolysis.

Production of Acetone, Butanol and Ethanol as Bioenergy Source Materials by Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) using Different Substrates

In the effort of developing bioenergy source materials, a laboratorium study was performed to investigate the effects of substrate types and concentrations on the production of acetone-butanol-ethanol (ABE) from various substrates by Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) in defined TYA (Tryptone-Yeast extract-Acetate) media. The results demonstrated that the ABE ratios produced by the strain N1-4 were greatly influenced by the types of substrate and the concentrations being used. It was also shown that fermentation of disaccharides (cellobiose and dextrin) by the strain N1-4 could give relatively as high butanol and ABE yields as glucose fermentation after 24 h fermentation time. The strain N1-4 was also found to be able to ferment xylans from birchwood sources producing a relatively high ABE concentration, especially at a prolonged incubation time (after 48 h incubation period). A subsequent experiment using several different concentrations of glucose or cellobiose revealed that the higher the concentration of the substrate being used, then the higher the total ABE concentration or productivity could be obtained but not necessarily in the same increasing ratio. To the best of our knowledge, there was no other previous study about the effect of substrate type and concentration on the ABE ratio by C. saccharoperbutylacetonicum N1-4 (ATCC 13564) using various substrates in defined TYA media, specifically by using xylans and dextrin substrates.

Enhancement of ABE fermentation through regulation of ammonium acetate and D–xylose uptake from acid-pretreated corncobs

Clostridium acetobutylicum TISTR 1462 and Clostridium beijerinckii TISTR 1461 were chosen to optimize acetone–butanol–ethanol (ABE) fermentation by using glucose as a carbon source. The enhancement in its productivity by adding various concentrations of ammonium acetate was studied. Then, the variation of glucose/xylose ratios in the pre-grown medium was investigated. The results showed that both increased ammonium acetate in the production medium and D–xylose in the pre-grown medium could produce more ABE. With these conditions, using corncob hydrolysate as a substrate, 20.58 g/L ABE was produced from C. beijerinckii TISTR 1461 with 0.44 g/L/h and 0.45 of ABE productivity and yield, respectively.

Acetone–butanol–ethanol production with high productivity using Clostridium acetobutylicum BKM19

Conventional acetone-butanol-ethanol (ABE) fermentation is severely limited by low solvent titer and productivities. Thus, this study aims at developing an improved Clostridium acetobutylicum strain possessing enhanced ABE production capability followed by process optimization for high ABE productivity. Random mutagenesis of C. acetobutylicum PJC4BK was performed by screening cells on fluoroacetate plates to isolate a mutant strain, BKM19, which exhibited the total solvent production capability 30.5% higher than the parent strain. The BKM19 produced 32.5 g L(-1) of ABE (17.6 g L(-1) butanol, 10.5 g L(-1) ethanol, and 4.4 g L(-1) acetone) from 85.2 g L(-1) glucose in batch fermentation. A high cell density continuous ABE fermentation of the BKM19 in membrane cell-recycle bioreactor was studied and optimized for improved solvent volumetric productivity. Different dilution rates were examined to find the optimal condition giving highest butanol and ABE productivities. The maximum butanol and ABE productivities of 9.6 and 20.0 g L(-1) h(-1) , respectively, could be achieved at the dilution rate of 0.85 h(-1) . Further cell recycling experiments were carried out with controlled cell-bleeding at two different bleeding rates. The maximum solvent productivities were obtained when the fermenter was operated at a dilution rate of 0.86 h(-1) with the bleeding rate of 0.04 h(-1) . Under the optimal operational condition, butanol and ABE could be produced with the volumetric productivities of 10.7 and 21.1 g L(-1) h(-1) , and the yields of 0.17 and 0.34 g g(-1) , respectively. The obtained butanol and ABE volumetric productivities are the highest reported productivities obtained from all known-processes.

Enhanced Acetone, Butanol, and Ethanol Fermentation by Clostridium accharoperbutylacetonicum N1-4 (ATCC 13564) in a Chemically Defined Medium: Effect of Iron and Initial pH on ABE Ratio

Batch studies were performed to investigate the performance of Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) in acetone-butanol-ethanol (ABE) fermentation as affected by iron and initial pH in defined TYA (Tryptone-Yeast extract-Acetate) media. Different concentrations of FeSO 4 .7H 2 O in the TYA media were found to influence the ABE fermentation process resulting in different ABE ratios. From the experiment with different concentrations of FeSO 4 .7H 2 O, it was also found that lag phases at initial pH of 4.4 were longer than those at initial pH of 6.5, however they could still have higher ABE productivity values. Addition of 0.003 g L -1 FeSO 4 .7H 2 O could give the highest ABE production with both initial pH of 6.5 and 4.4. With more than 0.01 g L -1 FeSO 4 .7H 2 O, ratios of acetone to butanol (0.50 - 0.53) were higher at initial pH of 4.4 than those (0.26 - 0.28) at initial pH of 6.5. Those differences were not obtained with low concentration of FeSO 4 .7H 2 O among the same initial pH. It was also confirmed that initial pH affected ABE production significantly more than FeSO 4 .7H 2 O by statistical analysis.

Effects of nutritional enrichment on the production of acetone-butanol-ethanol (ABE) by Clostridium acetobutylicum

Clostridium acetobutylicum is an industrially important organism that produces acetone-butanol-ethanol (ABE). The main objective of this study was to characterize the effects of increased cell density on the production of ABE during the phase transition from acidogenesis to solventogenesis in C. acetobutylicum. The increased ABE productivity of C. acetobutylicum was obtained by increasing the cell density using a newly designed medium (designated C. a cetobutylicum medium 1; CAM1). The maximum OD(600) value of C. acetobutylicum ATCC 824 strain obtained with CAM1 was 19.7, which is 1.8 times higher than that obtained with clostridial growth medium (CGM). The overall ABE productivity obtained in the CAM1-fermetation of the ATCC 824 strain was 0.83 g/L/h, which is 1.5 times higher than that (0.55 g/L/h) obtained with CGM. However, the increased productivity obtained with CAM1 did not result in an increase in the final ABE titer, because phase transition occurred at a high titer of acids.

Screening and characteristics of a butanol-tolerant strain and butanol production from enzymatic hydrolysate of NaOH-pretreated corn stover

As a gasoline substitute, butanol has advantages over traditional fuel ethanol in terms of energy density and hydroscopicity. However, solvent production appeared limited by butanol toxicity. The strain of Clostridium acetobutylicum was subjected to mutation by mutagen of N-methyl-N'-nitro-N-nitrosoguanidine for 0.5h. Screening of mutants was done according to the individual resistance to butanol. A selected butanol-resistant mutant, strain 206, produced 50% higher solvent concentrations than the wild-type strain when 60g glucose/l was employed as substrate. The strain was also able to produce solvents of 23.47g/l in 80g/l glucose P2 medium after 70h fermentation, including 5.41g acetone/l, 15.05g butanol/l and 3.02g ethanol/l, resulting in an ABE yield and productivity of 0.32g/g and 0.34g/(lh). Subsequently, Acetone-butanol-ethanol (ABE) production from enzymatic hydrolysate of NaOH-pretreated corn stover was investigated in this study. An ABE yield of 0.41 and a productivity of 0.21g/(lh) was obtained, compared to the yield of 0.33 and the productivity of 0.20g/(lh) in the control medium containing 52.47 mixed sugars. However, it is important to note that although strain 206 was able to utilize all the glucose rapidly in the hydrolysate, only 32.9% xylose in the hydrolysate was used after fermentation stopped compared to 91.4% xylose in the control medium. Strain 206 was shown to be a robust strain for ABE production from lignocellulosic materials and has a great potential for industrial application.

Enhancement of butanol production and reducing power using a two-stage controlled-pH strategy in batch culture of Clostridium acetobutylicum XY16

The effects of pH control on the process of acetone/butanol/ethanol (ABE) production in batch cultures of Clostridium acetobutylicum XY16 have been investigated. Based on the specific acid- and solvent-forming rates in batch fermentation at different pH values (from 4.3 to 6.0), a two-stage controlled-pH strategy was developed in which the pH was shifted from 5.5 to 4.9 after a dry cell weight of 0.5 g L(-1) was achieved. By applying this strategy, the maximum ABE concentration and productivity reached 20.3 g L(-1) and 0.63 g L(-1) h (-1), and were significantly improved by 12.2 and 40.1 %, respectively, compared with the process with no pH control. In addition, reducing power capability was significantly enhanced by this strategy. The two-stage controlled-pH strategy was a convenient and rapid method for high intensity ABE production.

Intensification of Biobutanol Production in Batch Oscillatory Baffled Bioreactor

Biobutanol is a high value biofuel and potentially a better fuel extender than ethanol. The market demand is expected to increase dramatically, if biobutanol can be produced economically via the ABE (acetone, butanol ethanol) fermentation. One way to improve the ABE yield and productivity is through intensification of the fermentation process. In this work, a novel intensified bioreactor called the oscillatory baffled bioreactor (OBB) was evaluated for this process. Batch ABE fermentations were conducted in OBBs at various “oscillatory Reynolds numbers” in the range 0 to 1870 and in stirred tank reactors (STRs) at various stirrer speeds in the range 0 to 200 rpm. The fermentations were performed anaerobically using clostridia strain Clostridium GBL1082 at constant temperature. In the OBB, the highest ABE yield achieved was 0.35 g/g (of g ABE produced per g glucose used) which was comparable to yield achieved in the STR. The highest productivity achieved in the OBB was 0.22 g/L/h, 38% higher than the maximum achieved in the STR. It was also observed that use of the highest mixing intensities (for both OBBs and STRs) within the studied range resulted in higher acid concentration, suggesting that acids were not reassimilated efficiently. It is likely that there is a balance between achieving uniform suspension of the bio-fluid and the adverse effects of shear in both bioreactors.

Biobutanol production from rice bran and de-oiled rice bran by Clostridium saccharoperbutylacetonicum N1-4

Rice bran (RB) and de-oiled rice bran (DRB) have been treated and used as the carbon source in acetone-butanol-ethanol (ABE) production using Clostridium saccharoperbutylacetonicum N1-4. The results showed that pretreated DRB produced more ABE than pretreated RB. Dilute sulfuric acid was the most suitable treatment method among the various pretreatment methods that were applied. The highest ABE obtained was 12.13 g/L, including 7.72 g/L of biobutanol, from sulfuric acid. The enzymatic hydrolysate of DRB (ESADRB), when treated with XAD-4 resin, resulted in an ABE productivity and yield of 0.1 g/L h and 0.44 g/g, respectively. The results also showed that the choice of pretreatment method for RB and DRB is an important factor in butanol production.

Effect of cellulosic sugar degradation products (furfural and hydroxymethyl furfural) on acetone–butanol–ethanol (ABE) fermentation using Clostridium beijerinckii P260

Studies were performed to identify chemical compounds present in wheat straw hydrolysate (WSH) that enhance acetone butanol ethanol (ABE) productivity. These compounds were identified as furfural and hydroxymethyl furfural (HMF). Control experiment resulted in the production of 21.38gL−1 ABE with a productivity of 0.30gL−1h−1. WSH contained 0.04–0.34gL−1 furfural and 0.12–0.88gL−1 HMF. Addition of furfural to the fermentation medium at a concentration of 0.50gL−1 resulted in a productivity of 0.88gL−1h−1 which is 293% of the productivity obtained in control experiments. Supplementation with 1.00gL−1 HMF into the fermentation medium produced 25.27gL−1 ABE with a productivity of 0.68gL−1h−1. A combination of furfural (0.50gL−1) and HMF (0.50gL−1) also enhanced ABE production and productivity when added to the fermentation medium. Both furfural and HMF enhanced specific productivity (233–308%) of ABE. In brief, WSH contained an adequate concentration of furfural and HMF that enhanced ABE productivity, specific productivity, and product concentration.

Assessment of in situ butanol recovery by vacuum during acetone butanol ethanol (ABE) fermentation

AbstractBACKGROUND: Butanol fermentation is product limiting owing to butanol toxicity to microbial cells. Butanol (boiling point: 118 °C) boils at a higher temperature than water (boiling point: 100 °C) and application of vacuum technology to integrated acetone–butanol–ethanol (ABE) fermentation and recovery may have been ignored because of direct comparison of boiling points of water and butanol. This research investigated simultaneous ABE fermentation using Clostridium beijerinckii 8052 and in situ butanol recovery by vacuum. To facilitate ABE mass transfer and recovery at fermentation temperature, batch fermentation was conducted in triplicate at 35 °C in a 14 L bioreactor connected in series with a condensation system and vacuum pump.RESULTS: Concentration of ABE in the recovered stream was greater than that in the fermentation broth (from 15.7 g L−1 up to 33 g L−1). Integration of the vacuum with the bioreactor resulted in enhanced ABE productivity by 100% and complete utilization of glucose as opposed to a significant amount of residual glucose in the control batch fermentation.CONCLUSION: This research demonstrated that vacuum fermentation technology can be used for in situ butanol recovery during ABE fermentation and that C. beijerinckii 8052 can tolerate vacuum conditions, with no negative effect on cell growth and ABE production. Copyright © 2011 Society of Chemical Industry

Production of butanol (a biofuel) from agricultural residues: Part II – Use of corn stover and switchgrass hydrolysates☆

Abstract Acetone butanol ethanol (ABE) was produced from hydrolysed corn stover and switchgrass using Clostridium beijerinckii P260. A control experiment using glucose resulted in the production of 21.06 g L−1 total ABE. In this experiment an ABE yield and productivity of 0.41 and 0.31 g L−1 h−1 was achieved, respectively. Fermentation of untreated corn stover hydrolysate (CSH) exhibited no growth and no ABE production; however, upon dilution with water (two fold) and wheat straw hydrolysate (WSH, ratio 1:1), 16.00 and 18.04 g L−1 ABE was produced, respectively. These experiments resulted in ABE productivity of 0.17–0.21 g L−1 h−1. Inhibitors present in CSH were removed by treating the hydrolysate with Ca(OH)2 (overliming). The culture was able to produce 26.27 g L−1 ABE after inhibitor removal. Untreated switchgrass hydrolysate (SGH) was poorly fermented and the culture did not produce more than 1.48 g L−1 ABE which was improved to 14.61 g L−1. It is suggested that biomass pretreatment methods that do not generate inhibitors be investigated. Alternately, cultures resistant to inhibitors and able to produce butanol at high concentrations may be another approach to improve the current process.

Butanol production from wheat straw by simultaneous saccharification and fermentation using Clostridium beijerinckii: Part I—Batch fermentation

Five different processes were investigated to produce acetone–butanol–ethanol (ABE) from wheat straw (WS) by Clostridium beijerinckii P260. The five processes were fermentation of pretreated WS (Process I), separate hydrolysis and fermentation of WS to ABE without removing sediments (Process II), simultaneous hydrolysis and fermentation of WS without agitation (Process III), simultaneous hydrolysis and fermentation with additional sugar supplementation (Process IV), and simultaneous hydrolysis and fermentation with agitation by gas stripping (Process V). During the five processes, 9.36, 13.12, 11.93, 17.92, and 21.42 g L−1 ABE was produced, respectively. Processes I–V resulted in productivities of 0.19, 0.14, 0.27, 0.19, and 0.31 g L−1 h−1, respectively. It should be noted that Process V resulted in the highest productivity (0.31 g L−1 h−1). In the control experiment (using glucose), an ABE productivity of 0.30 g L−1 h−1 was achieved. These results suggest that simultaneous hydrolysis of WS to sugars and fermentation to butanol/ABE is an attractive option as compared with more expensive glucose to ABE fermentation. Further development of enzymes for WS hydrolysis with optimum characteristics similar to fermentation would make conversion of WS to butanol/ABE even more attractive.

High production of acetone–butanol–ethanol with high cell density culture by cell-recycling and bleeding

A continuous acetone–butanol–ethanol (ABE) production system with high cell density obtained by cell-recycling of Clostridium saccharoperbutylacetonicum N1-4 has been studied. In conventional continuous culture of ABE without cell-recycling, the cell concentration was below 5.2 g l −1 and the maximum ABE productivity was only 1.85 g l −1 h −1 at a dilution rate of 0.20 h −1. To obtain a high cell density at a faster rate, we concentrated the solventogenic cells of the broth 10 times by membrane filtration and were able to obtain approximately 20 g l −1 of active cells after only 12 h of cultivation. Continuous culture with cell-recycling was then started, and the cell concentration increased gradually through cultivation to a value greater than 100 g l −1. The maximum ABE productivity of 11.0 g l −1 h −1 was obtained at a dilution rate of 0.85 h −1. However, a cell concentration greater than 100 g l −1 resulted in heavy bubbling and broth outflow, which made it impossible to carry out continuous culture. Therefore, to maintain a stable cell concentration, cell-bleeding was performed together with cell-recycling. At dilution rates of 0.11 h −1 and above for cell-bleeding, continuous culture with cell-recycling could be operated for more than 200 h without strain degeneration and the overall volumetric ABE productivity of 7.55 g l −1 h −1 was achieved at an ABE concentration of 8.58 g l −1.

Acetone butanol ethanol (ABE) production from concentrated substrate: reduction in substrate inhibition by fed-batch technique and product inhibition by gas stripping.

Acetone butanol ethanol (ABE) was produced in an integrated fed-batch fermentation-gas stripping product-recovery system using Clostridium beijerinckii BA101, with H(2) and CO(2) as the carrier gases. This technique was applied in order to eliminate the substrate and product inhibition that normally restricts ABE production and sugar utilization to less than 20 g l(-1) and 60 g l(-1), respectively. In the integrated fed-batch fermentation and product recovery system, solvent productivities were improved to 400% of the control batch fermentation productivities. In a control batch reactor, the culture used 45.4 g glucose l(-1) and produced 17.6 g total solvents l(-1) (yield 0.39 g g(-1), productivity 0.29 g l(-1) h(-1)). Using the integrated fermentation-gas stripping product-recovery system with CO(2) and H(2) as carrier gases, we carried out fed-batch fermentation experiments and measured various characteristics of the fermentation, including ABE production, selectivity, yield and productivity. The fed-batch reactor was operated for 201 h. At the end of the fermentation, an unusually high concentration of total acids (8.5 g l(-1)) was observed. A total of 500 g glucose was used to produce 232.8 g solvents (77.7 g acetone, 151.7 g butanol, 3.4 g ethanol) in 1 l culture broth. The average solvent yield and productivity were 0.47 g g(-1) and 1.16 g l(-1) h(-1), respectively.