scholarly journals Evaluation of Media Components and Process Parameters in a Sensitive and Robust Fed-Batch Syngas Fermentation System with Clostridium ljungdahlii

Fermentation ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 61 ◽  
Author(s):  
Alba Infantes ◽  
Michaela Kugel ◽  
Anke Neumann
Keyword(s):  
Yeast Extract ◽  
Process Parameters ◽  
Gas Flow ◽  
Limiting Factor ◽  
Syngas Fermentation ◽  
Fermentation Products ◽  
Clostridium Ljungdahlii ◽  
Lower Productivity ◽  
Acetogenic Bacteria ◽  
Gas Consumption

The fermentation of synthesis gas, or syngas, by acetogenic bacteria can help in transitioning from a fossil-fuel-based to a renewable bioeconomy. The main fermentation products of Clostridium ljungdahlii, one of such microorganisms, are acetate and ethanol. A sensitive, robust and reproducible system was established for C. ljungdahlii syngas fermentation, and several process parameters and medium components (pH, gas flow, cysteine and yeast extract) were investigated to assess its impact on the fermentation outcomes, as well as real time gas consumption. Moreover, a closed carbon balance could be achieved with the data obtained. This system is a valuable tool to detect changes in the behavior of the culture. It can be applied for the screening of strains, gas compositions or media components, for a better understanding of the physiology and metabolic regulation of acetogenic bacteria. Here, it was shown that neither yeast extract nor cysteine was a limiting factor for cell growth since their supplementation did not have a noticeable impact on product formation or overall gas consumption. By combining the lowering of both the pH and the gas flow after 24 h, the highest ethanol to acetate ratio was achieved, but with the caveat of lower productivity.

scholarly journals Effect of Cysteine, Yeast Extract, pH Regulation and Gas Flow on Acetate and Ethanol Formation and Growth Profiles of Clostridium ljungdahlii Syngas Fermentation

2020 ◽  
Author(s):  
Alba Infantes ◽  
Michaela Kugel ◽  
Anke Neumann
Keyword(s):  
Yeast Extract ◽  
Metabolic Regulation ◽  
Gas Flow ◽  
Product Formation ◽  
Fermentation Products ◽  
Clostridium Ljungdahlii ◽  
Lower Productivity ◽  
Acetogenic Bacteria ◽  
Gas Consumption ◽  
Growth Product

ABSTRACTThe fermentation of synthesis gas, or syngas, which consists mainly of CO, CO2 and H2 by acetogenic bacteria has the potential to help in transitioning from a fossil-fuel-based to a renewable bio-economy. Clostridium ljungdahlii, one of such microorganisms, has as main fermentation products acetate and ethanol. Multiple research efforts have been directed towards understanding how the metabolism and the product formation of this, and other acetogenic bacteria, can be directed towards increasing productivities and yields; nonetheless, transferring those findings to a particular set-up can prove challenging. This study used a well-established and robust fed-batch fermentation system with C. ljungdahlii to look into the effects of different fermentation pH profiles, gas flow, and the supplementation with additional yeast extract or cysteine on growth, product formation ratios, yields, and productivities, as well as gas consumption. Neither yeast extract nor cysteine supplementation had a noticeable impact on cell growth, product formation or overall gas consumption. The lowering of the pH proved mainly detrimental, with decreased productivities and no improvement in ethanol ratios. The most notable shift towards ethanol was achieved by the combination of lowering both the pH and the gas flow after 24 h, but with the caveat of lower productivity. The obtained results, unexpected to some extent, highlight the necessity for a better understanding of the physiology and the metabolic regulation of acetogenic bacteria in order for this process to become more industrially relevant.

scholarly journals Parameters Optimization of Auxiliary Gas Process for Double-Wire SS316L Stainless Steel Arc Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 190
Author(s):  
Wei Wu ◽  
Jiaxiang Xue ◽  
Wei Xu ◽  
Hongyan Lin ◽  
Heqing Tang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Process Parameters ◽  
Evaluation System ◽  
Gas Flow ◽  
Interactive Effect ◽  
Parameters Optimization ◽  
Heat Accumulation ◽  
Auxiliary Process ◽  
Strength And Stiffness

Serious heat accumulation limits the further efficiency and application in additive manufacturing (AM). This study accordingly proposed a double-wire SS316L stainless steel arc AM with a two-direction auxiliary gas process to research the effect of three parameters, such as auxiliary gas nozzle angle, auxiliary gas flow rate and nozzle-to-substrate distance on depositions, then based on the Box–Behnken Design response surface, a regression equation between three parameters and the total score were established to optimized parameters by an evaluation system. The results showed that samples with nozzle angle of 30° had poor morphology but good properties, and increasing gas flow or decreasing distance would enhance the airflow strength and stiffness, then strongly stir the molten pool and resist the interference. Then a diverse combination of auxiliary process parameters had different influences on the morphology and properties, and an interactive effect on the comprehensive score. Ultimately the optimal auxiliary gas process parameters were 17.4°, 25 L/min and 10.44 mm, which not only bettered the morphology, but refined the grains and improved the properties due to the stirring and cooling effect of the auxiliary gas, which provides a feasible way for quality and efficiency improvements in arc additive manufacturing.

scholarly journals Preparation of Polyacrylonitrile Nanofibers by Solution Blowing Process

2013 ◽  
Vol 8 (1) ◽  
pp. 155892501300800 ◽  
Author(s):  
Xupin Zhuang ◽  
Kaifei Jia ◽  
Bowen Cheng ◽  
Ketian Guan ◽  
Weimin Kang ◽  
...  
Keyword(s):  
Process Parameters ◽  
Driving Force ◽  
Gas Flow ◽  
Feeding Rate ◽  
Solution Concentration ◽  
Alternative Technique ◽  
Solution Blowing ◽  
Innovative Process ◽  
Gas Cavity ◽  
Pan Fibers

Solution blowing is an innovative process for spinning nanofibers from polymer solutions using high-velocity gas flow as fiber-forming driving force. Polyacrylonitrile (PAN) nanofibers were prepared using PAN solutions in N, N-Dimethylformamide and the morphologies of the fibers were examined using a scanning electron microscope. The process parameters including solution concentration, gas pressure supplied to the gas cavity, and solution-feeding rate were varied to investigate their effects on the morphologies of the fibers. PAN fibers were successfully prepared in the form of a nonwoven web. The fiber diameters mostly ranged in hundreds of nanometers and were affected by the process parameters. Results indicated that solution blowing is an alternative technique for manufacturing nonwoven webs that consist of micro- and nanofibers.

scholarly journals Experimental Design to Improve Cell Growth and Ethanol Production in Syngas Fermentation by Clostridium carboxidivorans

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Carolina Benevenuti ◽  
Alanna Botelho ◽  
Roberta Ribeiro ◽  
Marcelle Branco ◽  
Adejanildo Pereira ◽  
...  
Keyword(s):  
Cell Growth ◽  
Ethanol Production ◽  
Yeast Extract ◽  
Biomass Gasification ◽  
Culture Collection ◽  
Medium Composition ◽  
Syngas Fermentation ◽  
The Cost ◽  
Clostridium Carboxidivorans ◽  
Peptone Yeast Extract Glucose

Fermentation of gases from biomass gasification, named syngas, is an important alternative process to obtain biofuels. Sequential experimental designs were used to increase cell growth and ethanol production during syngas fermentation by Clostridium carboxidivorans. Based on ATCC (American Type Culture Collection) 2713 medium composition, it was possible to propose a best medium composition for cell growth, herein called TYA (Tryptone-Yeast extract-Arginine) medium and another one for ethanol production herein called TPYGarg (Tryptone-Peptone-Yeast extract-Glucose-Arginine) medium. In comparison to ATCC® 2713 medium, TYA increased cell growth by 77%, reducing 47% in cost and TPYGarg increased ethanol production more than four-times, and the cost was reduced by 31%. In 72 h of syngas fermentation in TPYGarg medium, 1.75-g/L of cells, 2.28 g/L of ethanol, and 0.74 g/L of butanol were achieved, increasing productivity for syngas fermentation.

scholarly journals Side-by-Side Comparison of Clean and Biomass-Derived, Impurity-Containing Syngas as Substrate for Acetogenic Fermentation with Clostridium ljungdahlii

Fermentation ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 84
Author(s):  
Alba Infantes ◽  
Michaela Kugel ◽  
Klaus Raffelt ◽  
Anke Neumann
Keyword(s):  
Biomass Gasification ◽  
Product Formation ◽  
Inhibitory Effects ◽  
Fed Batch ◽  
Gaseous Mixtures ◽  
Clostridium Ljungdahlii ◽  
Acetogenic Bacteria ◽  
Fed Batch Fermentation ◽  
Total Productivity ◽  
The Impact

Syngas, the product of biomass gasification, can play an important role in moving towards the production of renewable chemical commodities, by using acetogenic bacteria to ferment those gaseous mixtures. Due to the complex and changing nature of biomass, the composition and the impurities present in the final biomass-derived syngas will vary. Because of this, it is important to assess the impact of these factors on the fermentation outcome, in terms of yields, productivity, and product formation and ratio. In this study, Clostridium ljungdahlii was used in a fed-batch fermentation system to analyze the effect of three different biomass-derived syngases, and to compare them to equivalent, clean syngas mixtures. Additionally, four other clean syngas mixtures were used, and the effects on product ratio, productivity, yield, and growth were documented. All biomass-derived syngases were suitable to be used as substrates, without experiencing any complete inhibitory effects. From the obtained results, it is clear that the type of syngas, biomass-derived or clean, had the greatest impact on product formation ratios, with all biomass-derived syngases producing more ethanol, albeit with lesser total productivity.

scholarly journals The Effect of Process Parameters on the Microstructure and Mechanical Properties of AW5083 Aluminum Laser Weld Joints

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1443 ◽  
Author(s):  
Maroš Vyskoč ◽  
Miroslav Sahul ◽  
Mária Dománková ◽  
Peter Jurči ◽  
Martin Sahul ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Process Parameters ◽  
Flow Rate ◽  
Weld Joint ◽  
Gas Flow ◽  
Filler Wire ◽  
Shielding Gas ◽  
Gas Flow Rate ◽  
Weld Joints

In this article, the effect of process parameters on the microstructure and mechanical properties of AW5083 aluminum alloy weld joints welded by a disk laser were studied. Butt welds were produced using 5087 (AlMg4.5MnZr) filler wire, with a diameter of 1.2 mm, and were protected from the ambient atmosphere by a mixture of argon and 30 vol.% of helium (Aluline He30). The widest weld joint (4.69 mm) and the highest tensile strength (309 MPa) were observed when a 30 L/min shielding gas flow rate was used. Conversely, the narrowest weld joint (4.15 mm) and the lowest tensile strength (160 MPa) were found when no shielding gas was used. The lowest average microhardness (55.4 HV0.1) was recorded when a 30 L/min shielding gas flow rate was used. The highest average microhardness (63.9 HV0.1) was observed when no shielding gas was used. In addition to the intermetallic compounds, β-Al3Mg2 and γ-Al12Mg17, in the inter-dendritic areas of the fusion zone (FZ), Al49Mg32, which has an irregular shape, was recorded. The application of the filler wire, which contains zirconium, resulted in grain refinement in the fusion zone. The protected weld joint was characterized by a ductile fracture in the base material (BM). A brittle fracture of the unshielded weld joint was caused by the presence of Al2O3 particles. The research results show that we achieved the optimal welding parameters, because no cracks and pores were present in the shielded weld metal (WM).

Preparation of high-oriented molybdenum thin films using DC reactive magnetronsputtering

2017 ◽  
Vol 31 (07) ◽  
pp. 1750059 ◽  
Author(s):  
Zhengguo Shang ◽  
Dongling Li ◽  
She Yin ◽  
Shengqiang Wang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Surface Roughness ◽  
Process Parameters ◽  
Gas Flow ◽  
Lattice Mismatch ◽  
Practical Significance ◽  
Process Time ◽  
Process Conditions ◽  
Influence Of Process Parameters

Since molybdenum (Mo) thin film has been used widely recently, it attracts plenty of attention, like it is a good candidate of back contact material for CuIn[Formula: see text]Ga[Formula: see text]Se[Formula: see text]S[Formula: see text] (CIGSeS) solar cells development; thanks to its more conductive and higher adhesive property. Besides, molybdenum thin film is an ideal material for aluminum nitride (AlN) thin film preparation and attributes to the tiny (−1.0%) lattice mismatch between Mo and AlN. As we know that the quality of Mo thin film is mainly dependent on process conditions, it brings a practical significance to study the influence of process parameters on Mo thin film properties. In this work, various sputtering conditions are employed to explore the feasibility of depositing a layer of molybdenum film with good quality by DC reactive magnetron sputtering. The influence of process parameters such as power, gas flow, substrate temperature and process time on the crystallinity and crystal orientation of Mo thin films is investigated. X-ray diffraction (XRD) measurements and atomic force microscope (AFM) are used to characterize the properties and surface roughness, respectively. According to comparative analysis on the results, process parameters are optimized. The full width at half maximum (FWHM) of the rocking curves of the (110) Mo is decreased to 2.7[Formula: see text], and the (110) Mo peaks reached [Formula: see text] counts. The grain size and the surface roughness have been measured as 20 Å and 3.8 nm, respectively, at 200[Formula: see text]C.

scholarly journals Application of Taguchi technique to optimize the gma welding parameters and study of fracture mode characterization of AISI 304H welded joints

2018 ◽  
Vol 9 (1) ◽  
pp. 9-16
Author(s):  
S. A. Rizvi
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Process Parameters ◽  
Flow Rate ◽  
Fracture Mode ◽  
Welded Joints ◽  
Gas Flow ◽  
Welding Parameters ◽  
Taguchi Technique ◽  
Gas Flow Rate

This research article is focusing on the optimization of different welding process parameters which affect the weldability of stainless steel (AISI) 304H, Taguchi technique was used to optimize the welding parameters and the fracture mode characterization was studied. A number of experiments have been conducted. L9 orthogonal array (OA) (3×3) was applied. Analysis of variance ( ANOVA) and signal to noise ratio (SNR) was applied to determine the effect of different welding parameters such as welding current, wire feed speed and gas flow rate on mechanical, microstructure properties of SS304H. Ultimate tensile strength (UTS), toughness, microhardness (VHN), and mode of fracture was examined to determine weldability of AISI 304H and it was observed from results that welding voltage has major impact whereas gas flow rate has minor impact on ultimate tensile strength of the welded joints. Optimum process parameters were found to be 23 V, 350 IPM travel speed of wire and 15 l/min gas flow rate for tensile strength and mode of fracture was ductile fracture for tensile test specimen.

scholarly journals Directing Clostridium ljungdahlii fermentation products via hydrogen to carbon monoxide ratio in syngas

2019 ◽  
Vol 124 ◽  
pp. 95-101 ◽  
Author(s):  
Joshua Jack ◽  
Jonathan Lo ◽  
Pin-Ching Maness ◽  
Zhiyong Jason Ren
Keyword(s):  
Carbon Monoxide ◽  
Fermentation Products ◽  
Clostridium Ljungdahlii

Enhancing fatigue resistance of activated tungsten inert gas welded UNS S32750 super duplex stainless steel by optimizing its technological properties

2020 ◽  
pp. 1-11
Author(s):  
A. Arunmani ◽  
T. Senthilkumar
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Duplex Stainless Steel ◽  
Fatigue Resistance ◽  
Process Parameters ◽  
Gas Flow ◽  
Welding Process ◽  
Travel Speed ◽  
Inert Gas ◽  
Super Duplex Stainless Steel

In engineering industries and heavy manufacturing plants, fatigue life of joints plays a pivotal role in determining the overall life span of the welded joint. In this paper, an advanced fusion joining technique, namely activated tungsten inert gas welding, was used for joining UNS S32750 super duplex stainless steel, with ZnO as activation flux. For the enhancement of fatigue resistance of joints, important welding process parameters were fluctuated according to a developed central composite design model. Empirical relationships were developed between the process parameters and the fatigue strength of the joints, which was correlated with the number of cycles to failure (NCF). Using analysis of variance, the significance of the developed fatigue model was ascertained. Using response surface methodology, optimization of process parameters for enhancement of fatigue resistance was done. It was observed that at the optimized activated tungsten inert gas weld process parameters of travel speed of welding torch at 69.85 mm/min, weld current at 125.20 A, and shielding gas flow rate at 14.77 L/min, a high fatigue life of 7.66396 × 108 NCF was obtained and the model was validated to very high predictability. Microstructural variations in the fatigue-tested specimens were evaluated for identifying the grain modifications.

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