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1.
Ethanol production in a bioreactor with integrated membrane distillation (MD) module has been investigated. A hydrophobic
capillary polypropylene membrane (Accurel PP V8/2 HF), with an external/internal diameter ratio, d
out/ d
in = 8.6 mm/5.5 mm and pore size 0.2 μm, was used in these studies. The products (mainly ethanol and acetic acid) formed during
the fermentation of sugar with Saccharomyces cerevisiae inhibited the process. These products were selectively removed from the fermentation broth by the MD process, which increased
the efficiency of the conversion of sugar to alcohol from 0.45 g to 0.5 g EtOH per g of fermented sucrose. The bioreactor
efficiency also increased by almost 30 %. Separation of alcohol by the MD generates a higher yield of ethanol in the permeate
than in the broth. The enrichment coefficient amounted to 4-8, and depended on the ethanol concentration in the broth. The
separated solutions did not wet the membrane in use for 2500 h of the MD experiments and the retention of inorganic solutes
was close to 100 %. 相似文献
2.
The characteristics of yeast sulfite metabolism in a multistage bioreactor system for beer fermentation were investigated. No sulfite was produced in the continuous stirred-tank reactor (CSTR). However, large amounts were produced in the packed-bed reactor (PBR). Production of sulfite in the PBR seems to be inevitable when it is operated continuously. In order to control the sulfite level in the young beer, the yeast needs to be reactivated into the growth phase. One possible strategy to achieve this is to aerate and periodically remove yeast clogged in the reactor once every 6–7 months before the sulfite level exceeds a given concentration (e.g., 20 mg/L). It was confirmed that sulfite production is closely related to the growth condition of the yeast and is therefore important to consider in the control strategy for sulfite when using the immobilized yeast reactor for beer production. 相似文献
3.
Batch suspension cultures of Catharanthus roseus G. Don were grown in a 5 L LKB Ultraferm fermenter, converted to operate as an airlift bioreactor, to test the suitability of such
a system for the mass culture of plant cells. Results show that the airlift system has considerable merits as a culture vessel
for such a purpose, including: conversion rates of carbohydrate substrate to cell mass equivalent to > 50% under optimum conditions.
(Operating under these conditions, growth rates of approximately 0.4 d -1 are typical). In the absence of the mechanical shear normally associated with mechanically driven bioreactors, the gently
agitated environment of the airlift vessel proves to be an ideal system for the growth of fragile plant cells. Use of a nozzle
sparger reduces the possibility of a high mass transfer coefficient, except at very high gassing rates, thereby eliminating
any interference with the growth rate caused by high rates of gaseous exchange. 相似文献
4.
A multistage bioreactor system for rapid beer fermentation was developed. The main fermentation process, which conventionally
requires 7 d, could be shortened to 2 d by this system. The concentration of esters and higher alcohols are major factors
in brewery fermentation, their production being closely related to the yeast growth phase. Yeast metabolism was successfully
subdivided into a growth and a restricted phase through a combination of a continuous stirredtank reactor (CSTR) and an immobilized
yeast packed-bed reactor (PBR). Production of higher alcohols was high in the CSTR because of its association with the level
of biosynthetic activity de novo. A small amount was also produced in the PBR, however, possibly a result of an overflow in carbohydrate metabolism. Ester
formation mainly occurred in the PBR, a linear increase in the level of ester being observed with flow through the PBR. The
reactor system control strategy was to maximize the level of both higher alcohol and ester formation. The CSTR/PBR control
range, based on extract consumption, was varied between 1:1 and 1:2. A ratio of 1:1 tended to create a flat beer, whereas
a ratio 1:2 gave a beer of richer quality. Amino acid uptake by the yeast directly contributed to a reduction in the wort
pH, whereas no relation could be observed between the level of organic acid production and pH. 相似文献
5.
The operational characterization of a fluidized-bed bioreactor for ethanol fermentation using Ca-alginate immobilized yeast
cells is described. An additional air stream is supplied to the fermenter to ensure and maintain satisfactory fluidization
behavior of beads and to avoid slug formation. The influence of physical properties such as bead density and liquid density
on the fluidization quality and stability are discussed. 相似文献
7.
The high sensitivity that can be attained using an enzymatic system and mediated by hydroquinone, has been verified by on-line interfacing of a rotating bioreactor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP, [EC 1.11.1.7], immobilized on a rotating disk, in presence of hydrogen peroxide catalyses the oxidation of hydroquinone to p-benzoquinone, whose electrochemical reduction back to hydroquinone is detected on glassy carbon electrode (GCE) surface at −0.15 V. Thus, when l-ascorbic acid is added to the solution, this acid is reduced chemically ( p-benzoquinone to hydroquinone) and acts as mediator of HRP, decreasing the peak current obtained proportionally to the increase of its concentration. The recovery of l-ascorbic acid from four samples ranged from 99.09 to 101.10%. This method could be used to determine l-ascorbic acid concentration in the range 12 nM-3.5 μM ( r = 0.998). The determination of l-ascorbic acid was possible with a limit of detection of 6 nM in the processing of as many as 25 samples h −1. The method was successfully applied for the analysis of l-ascorbic acid in pharmaceutical formulations. 相似文献
8.
An emulsion bioreactor for production of (2 R,3 S)-3-(4-methoxyphenyl) glycidic acid methyl ester ([-]MPGM) from a racemic mixture ([±]MPGM) using the lipase from Serratia marcescens has been proposed. Kinetics of hydrolyzing reaction and purification of (-)MPGM from the reaction mixture were investigated
to provide a basis for industrial application of this bioreactor. The hydrolyzing reaction in the bioreactor proceeded at
a rate that was first order in substrate concentration. The reaction rate was affected by a stirring speed and the ratio of
the aqueous phase containing lipase to the toluene phase containing substrate. Phase separation after the enzymatic reaction
was accomplished by addition of surfactant to the reaction mixture, and crystalline (-)MPGM with a chemical purity of 100%
and optical purity of 100% enantiomeric excess was obtained in a high yield of 40–43% by concentration of the toluene solution. 相似文献
9.
Immobilized cell utilization in tower-type bioreactor is one of the main alternatives being studied to improve the industrial bioprocess. Other alternatives for the production of β-lactam antibiotics, such as a cephalosporin C fed-batch process in an aerated stirred-tank bioreactor with free cells of Cephalosporium acremonium, or a tower-type bioreactor with immobilized cells of this fungus, have proven to be more efficient than the batch process. In the fed-batch process, it is possible to minimize the catabolite repression exerted by the rapidly utilization of carbon sources (such as glucose) in the synthesis of antibiotics by utilizing a suitable flow rate of supplementary medium. In this study, several runs for cephalosporin C production, each lasting 200 h, were conducted in a fed-batch tower-type bioreactor using different hydrolyzed sucrose concentrations. For this study's model, modifications were introduced to take intoaccount the influence of supplementary medium flow rate. The balance equations considered the effect of oxygen limitation inside the bioparticles. In the Monod-type rate equations, cell concentrations, substrate concentrations, and dissolved oxygen were included as reactants affecting the bioreaction rate. The set of differential equations was solved by the numerical method, and the values of the parameters were estimated by the classic nonlinear regression method following Marquardt's procedure with a 95% confidence interval. The simulation results showed that the proposed model fit well with the experimental data, and based on the experimental data and the mathematical model, an optimal mass flow rate to maximize the bioprocess productivity could be proposed. 相似文献
10.
The growth properties of Panax ginseng hairy roots transformed by Agrobacterium rhizogenes were compared between flask and aerated column or stirred bioreactor. In flask cultures, sucrose, initially 30 g/L, was nearly
exhausted after 45 d of culture. The pH of the medium dropped from 5.5 to 4.96 after 10 d, but afterward it gradually increased
to 6.4. After 45 d, hairy roots grew about 16-folds. The growth rate of hairy roots in air-bubble column or stirred bioreactor
cultures was 1.13 (1.11) to 1.23 (1.20) g fresh wt (dry wt)/(g of cells·d), respectively. For both bioreactors, growth was
about three times as high as in the flask cultivation. 相似文献
11.
The effect of concentration of an acrylamide–sodium acrylate copolymer in an aqueous solution on the crosslinking of macromolecules by the action of ionizing radiation was studied. It was shown that the efficiency of radiation crosslinking of the copolymer increased with an increase in the concentration of solution subject to irradiation, which was tentatively explained in terms of the existence of fluctuative entanglement network ensuring the approaching of macroradical sites and, thus, facilitating the combination reactions of macroradicals. 相似文献
12.
Studies have been carried out using immobilized Z. mobilis in fluidized-bed bioreactors and have emphasized operation during high productivity and conversion. The bacteria are immobilized
within small uniform beads (~1 to 1.5-mm diam) of K-carrageenan at cell loadings of 15-50 g (dry wt)/L. Conversion and productivity
were measured under a variety of conditions, including feedstocks, flow rates, temperature, pH, and column sizes (up to 2.5
m tall). Volumetric productivities of 50-120 g EtOH/h-L reactor volume have been achieved. Productivities of 60 g/h-L are
demonstrated from a 15% feed with residual glucose concentrations of less than 0.1% and 7.4% EtOH in the tallest fermentor.
Among feeds of 10, 15, and 20% dextrose, the 15% gave the highest productivity and avoided substrate inhibition. A temperature
of 30°C and pH 5 were the optimum conditions. The ethanol yield was shown to be nearly constant at 0.49 g EtOH/g glucose,
or 97% of the theoretical under a variety of conditions and transients. The biocatalyst beads have been shown to remain active
for two months. Nonsterile feed has been used for weeks without detrimental contamination. The advantages of this advanced
bioreactor system over conventional batch technology are discussed. 相似文献
13.
We explored the influence of dilution rate and pH in continuous cultures of Clostridium acetobutylicum. A 200-mL fibrous bed bioreactor was used to produce high cell density and butyrate concentrations at pH 5.4 and 35°C. By
feeding glucose and butyrate as a cosubstrate, the fermentation was maintained in the solventogenesis phase, and the optimal
butanol productivity of 4.6g/(L h) and a yield of 0.42 g/g were obtained at a dilution rate of 0.9h −1 and pH 4.3. Compared to the conventional acetone-butanol-ethanol fermentation, the new fermentation process greatly improved
butanol yield, making butanol production from corn an attractive alternative to ethanol fermentation. 相似文献
14.
Much attention has recently been devoted to the life and behaviour of pharmaceuticals in the water cycle. In this study the
behaviour of several pharmaceutical products in different therapeutic categories (analgesics and anti-inflammatory drugs,
lipid regulators, antibiotics, etc.) was monitored during treatment of wastewater in a laboratory-scale membrane bioreactor
(MBR). The results were compared with removal in a conventional activated-sludge (CAS) process in a wastewater-treatment facility.
The performance of an MBR was monitored for approximately two months to investigate the long-term operational stability of
the system and possible effects of solids retention time on the efficiency of removal of target compounds. Pharmaceuticals
were, in general, removed to a greater extent by the MBR integrated system than during the CAS process. For most of the compounds
investigated the performance of MBR treatment was better (removal rates >80%) and effluent concentrations of, e.g., diclofenac,
ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin, and ofloxacin were steadier than for the conventional system.
Occasionally removal efficiency was very similar, and high, for both treatments (e.g. for ibuprofen, naproxen, acetaminophen,
paroxetine, and hydrochlorothiazide). The antiepileptic drug carbamazepine was the most persistent pharmaceutical and it passed
through both the MBR and CAS systems untransformed. Because there was no washout of biomass from the reactor, high-quality
effluent in terms of chemical oxygen demand (COD), ammonium content (N-NH 4), total suspended solids (TSS), and total organic carbon (TOC) was obtained. 相似文献
15.
Saccharomyces cerevisiae cells ionically adsorbed onto hexamethylene-diamine-treated bagasse (maximum cell loading 0.410 g cells per gram of carrier, dry basis) were used in a packed bed bioreactor at 30 ± 1 °C with sucrose medium (pH 5.0). The dynamic behaviour resulting from perturbations in feed sugar concentration and feed flow rate was studied during the continuous bioconversion of sugar to ethanol. The time-dependent partial differential equations were solved numerically by the Crank-Nicolson method and the experimental data fit well with those computed from the model.The RNA and total protein levels and alcohol dehydrogenase enzyme activity during the transient phase were monitored in a continuous stirred tank bioreactor (free cells) and their levels provide a reasonable explanation of the experimentally observed behaviour. 相似文献
16.
Acetaldehyde has been produced biologically using whole-cell Pichia pastoris in a semibatch fermentor. Ethanol and air were fed continuously, and the product, acetaldehyde, was removed by the air stream.
Operation of the reactor exceeded 100 h, maintaining high alcohol oxidase activity. Low cell-mass concentration (9.9 g/L)
minimized product inhibition. Ethanol concentration in the broth, oxygen concentration in the air, and pH were evaluated for
their effects on the fermentation process. 相似文献
17.
A new potentially promising visible-light driven photobioreactor synthesizes fine chemical via photobiocatalysis by generating NADH in a non-enzymatic light-driven process and coupling it to the enzymatic dark reaction catalysis. 相似文献
18.
Enterococcus faecalis RKY1, a fumarate-reducing bacterium, was immobilized in an asymmetric hollow-fiber bioreactor (HFBR) for the continuous production
of succinic acid. The cells were inoculated into the shell side of the HFBR, which was operated in transverse mode. Since
the pH values in the HFBR declined during continuous operation to about 5.7, it was necessary to change the feed pH from 7.0
to 8.0 after 24 h of operation in order to enhance production of succinic acid. During continuous operation with a medium
containing fumarate and glycerol, the productivity of succinate was 3.0–10.9 g/(L·h) with an initial concentration of 30 g/L
of fumarate, 4.9–14.9 g/(L·h) with 50 g/L of fumarate, and 7.2–17.1 g/(L·h) with 80 g/L of fumarate for dilution rates between
0.1 and 0.4 h −1. The maximum productivity of succinate obtained by the HFBR (17.1 g of succinate /[L·h]) was 1.7 times higher than that of
the batch bioconversions (9.9 g of succinate /[L·h]) with 80 g/L of fumarate. Furthermore, the long-term stability of the
HFBR was demonstrated with a continuously efficient production of succinate for more than 15 d (360 h). 相似文献
19.
Manure waste from dairy farms has been used for methane production for decades, however, problems such as digester failure are routine. The problem has been investigated in small scale (1-2 L) digesters in the laboratory; however, very little scale-up to intermediate scales are available. We report production of methane in a 100-L digester and the results of an investigation into the effect of partial mixing induced by gas upflow/recirculation in the digester. The digester was operated for a period of about 70 d (with 16-d hydraulic retention time) with and without the mixing induced by gas recirculation through an internal draft tube. The results show a clear effect of mixing on digester operation. Without any mixing, the digester performance deteriorated within 30-50 d, whereas with mixing continuous production of methane was observed. This study demonstrates the importance of mixing and its critical role in design of large scale anaerobic digesters. 相似文献
20.
Manure waste from dairy farms has been used for methane production for decades, however, problems such as digester failure
are routine. The problem has been investigated in small scale (1–2 L) digesters in the laboratory; however, very little scale-up
to intermediate scales are available. We report production of methane in a 100-L digester and the results of an investigation
into the effect of partial mixing induced by gas upflow/recirculation in the digester. The digester was operated for a period
of about 70 d (with 16-d hydraulic retention time) with and without the mixing induced by gas recirculation through an internal
draft tube. The results show a clear effect of mixing on digester operation. Without any mixing, the digester performance
deteriorated within 30–50 d, whereas with mixing continuous production of methane was observed. This study demonstrates the
importance of mixing and its critical role in design of large scale anaerobic digesters. 相似文献
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