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  • 1
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l−1 yeast extract and 2.5 g l−1 polypeptone per 10 g l−1 whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l−1 nontreated whey and 7 g l−1 glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95% and 0.46 g (l h)−1, respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (l h)−1 for 20 g l−1 whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (l h)−1], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Periodic backflushing of tubular ceramic membrane filters with filtrate was employed to alleviate membrane fouling in a bioreactor with internal-filtration. As the model system, yeast fermentation was dealt with in this study. There existed optimum backflushing interval and time to give a maximum flux recovery. At 16 g/l of yeast cell concentration, the mean flux increased about 2.5 times by using such repeated operation cycles as consisted of 4.53 minutes for filtration, 4.5 seconds for intermission, and 40 seconds for backflushing. Effects of aeration, agitation speed, and yeast cell concentration were also investigated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess engineering 17 (1997), S. 343-348 
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Removal rates of a toxic pollutant-hydrogen sulfide were investigated using several light sources in photosynthetic desulfurization. An incandescent bulb has a broad spectrum starting from about 400 nm but emits most of its light energy beyond 800 nm as heat. LED710 among those sources saved energy considerably comparing with the incandescent light, but the scattering and absorption was a problem in light transmission within the deep region of a bioreactor due to its own weak light intensity. Fluorescent light was inefficient in desulfurization in comparison with light sources illuminating with wide wavelength range, because of the weak transmittance at the peak wavelength of 460 nm. A combination of LED710 and fluorescent lamp was estimated as an optimal light source in this study.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 3 (1988), S. 159-163 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The biological transformation from rifamycin B to rifamycin S was carried out with the live whole cells of Humicola sp., ATCC 20620, immobilized in a dual hollow fiber bioreactor (DHFBR). Humicola sp., inoculated in the DHFBR, proliferated successfully to a high density cell mass within the space between an outer silicone tubing and three inner polypropylene hollow fiber membranes. In order to control the cell growth a nitrogen deficient medium was fed. Conversion of rifamycin B continued for more than 30 d, whereas that of immobilized rifamycin B oxidase lasted only for 3 d in comparable conditions. In the DHFBR the volumetric productivity of rifamycin S was 0.65–1.03 mmol/(dm3 · h) with 60% conversion, while that in the rotating packed disk reactor was 0.27 mmol/(dm3 · h) with 40% conversion at a residence time of 0.5–1.5 h.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 8 (1993), S. 263-269 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Traditional application of computer to fermentation processes has focused on the measurement and control of parameters such as temperature, pH, vessel pressure, sparge rate, dissolved oxygen, substrate concentration, and product concentration. In a fed-batch reactor with the photosynthetic green sulfur bacterium Chlorobium thiosulfatophilum which converts hydrogen sulfide to elementary sulfur or sulfate, separate measurement of cell mass concentration and sulfur particle concentration turbidimetrically was difficult due to their combined contributions to the total turbidity. Instead of on-line measurement of many process variables, a model-based control of feed rate and illuminance was designed. Optimal operation condition relating feed rate vs. light intensity was obtained to suppress the accumulation of sulfate and sulfide, and to save light energy in a 4-1 photosynthetic fed-batch reactor. This relation was correlated with the inreasing cell mass concentration. A model which describes the cell growth by considering the light attenuation effects due to scattering and absorption, and to crowding effect of the cells, was established beforehand with the results from the experiments. Based on these optimal operating conditions and the cell growth model, automatic controls of feed rate and illuminance were carried out alternatively to the traditional application of computer to fermentation with on-line measurement, realtime response and adjustment of process variables.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 4 (1989), S. 275-281 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Four types of anaerobic upflow biofilters: non-packed (NP-AUBF), two-stage (2S-AUBF), multi-stage (MS-AUBF) and fully-packed (FP-AUBF), were tested for their start-up and operational performance characteristics. The volume of each filter was 12.1 dm3 (10 cm I.D.x155 cm in height). Stepwise seeding was conducted and the effect on the reduction of COD and gas production was monitored. When each reactor was loaded with 2 and 4 kg COD/m3-day of synthetic waste simulating alcohol production plant, 2S-, MS-, FP-AUBF had treatment efficiencies of 89–93%, while NP-AUBF showed efficiencies lower than 50%. As a conclusion, 2S- or MS-AUBF can be used as efficiently as FP-AUBF, while the amount of packings in the former is half that in FP-AUBF.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess engineering 17 (1997), S. 197-202 
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of oxygen transfer on the production of immobilized whole cell β-galactosidase has been evaluated. The encapsulated whole cell β-galactosidase was prepared by combining cell encapsulation and culture into one-step. Escherichia coli was encapsulated and cultured in the growth and production media to accumulate β-galactosidase in itself. Sunflower seed oil was coimmobilized to increase the oxygen transfer rate through the capsule membrane. The oxygen transfer rate increased 63 percent and the activity of β-galactosidase increased by 10 percent. The activity of encapsulated β-galactosidase obtained in the concentric air lift reactor was 86 percent higher than that in the shaking incubator. In the concentric air lift reactor, the accumulation of encapsulated whole cell β-galactosidase was primarily dependent on the capsule velocity. While the accumulation of specific β-galactosidase in the capsule increased with volumetric oxygen transfer coefficient, the cell biomass accumulated in the capsule decreased.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Filtration of ethanol fermentation medium and broth by using symmetric and asymmetric ceramic membranes has been studied in an internal filter bioreactor. Factors studied included membrane structure and pore size, medium sterilization, and concentrations of glucose, yeast extract in the medium, yeast cell and protein in broth. The aim was to determine the main factors responsible for the decline in filtration performance during ethanol fermentation by Saccharomyces cerevisiae. Flux index (Fi) of a new concept has been developed to evaluate the degree of flux decline during the membrane fouling process. Fi was defined as the ratio of the membrane flux at certain filtration time (t = t) to the initial (t = −0) flux of pure water, not the initial (t = +0) flux of the test fluid. Flux with sterilized medium was approximately two-fold higher than that with unsterilized medium although the reason could not be explained clearly. Glucose, interaction between glucose and yeast extract, yeast cells, and proteins in fermentation broth were found to play an important part in membrane fouling. Fi of the symmetric membrane decreased to a less extent than that of the asymmetric membrane with increasing glucose concentration. But, the result with various yeast cell concentrations turned out to be contrary. Fouling was more serious for asymmetric membrane during the filtration of fermentation supernatant. This was thought to be due to different fouling mechanisms for the two types of membrane.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Korean food wastes were anaerobically digested to produce volatile fatty acids (VFA) that can be used as a carbon source in biological nutrient removal in a sequential batch reactor (SBR). Acetate, propionate and butyrate were produced at a yield of 379–400 g VFA/kg VS0 (initial volatile solids). The ratio of SCOD (Soluble Chemical Oxygen Demand) of VFA to ammonia nitrogen (N) was in the range of 36.2–36.5 and the ratio of SCOD to phosphorus was between 151 and 162. The removal rate of nitrogen and phosphorus improved from 44% and 37% to 92% and 73%, respectively when the VFA were added to the influent of the Taejon municipal wastewater plant. The concentration of nitrogen and phosphorus were maintained below 3 mg/l and 1 mg/l, respectively. The N- and P-content of the food waste was low enough not to influence the final N- and P-concentrations of the wastewater.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An internal membrane-filtration bioreactor system with periodic fouling removal and on-line cell measurement was employed for long-term continuous ethanol production from glucose in order to prove its performance and practicality. The bioreactor system developed in this study was successfully operated for 2 months with no problems in the maintenance of filtration flux. The maximum productivity obtained in this study was about 13 g/l-h which was ca. 3.3 times higher than that obtained in a conventional chemostat without cell retention by membrane. In another run of continuous culture, the laser turbidimeter used for the on-line monitoring of cell concentration showed a stable performance for 45 days without sensitivity loss due to fouling.
    Type of Medium: Electronic Resource
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