摘要:

AbstractSwine manure has a very high pollution potential and obnoxious odor. Large farms particularly are confronted with a manure disposal problem since environmentally acceptable solutions are now required by government regulations. Swine manure was found to be a good source of supplementary nutrients to ferment wheat straw into single‐cell protein (SCP) withChaetomium cellulolyticumwhen 0.13g (NH4)2SO4/g solid was used as an additional source of N. In batch fermentations, inhibitory effects, possibly due to soluble released from the straw during alkali or acid pretreatment, were overcome by starting the fermentation at about pH 7.0 and then reducing it to 5.0 during growth. An overall protein productivity of up to 66 mg/L h was obtained from a slurry mixture of 1% w/v solids of manure and straw. This compares favorably with 99 mg/L h when manure was fermented with glucose instead of straw as the main carbon source. A high protein productivity of 200 mg/L h was obtained from a slurry mixture containing anaerobically prefermented swine manure liquor and 1.5% w/v solids from straw. The final products of the manure and straw fermentations contained 25–30% DW crude protein and 6–20% DW cellulose and the materials were free of the original obnoxious odor and undesirable microbial contamin

ISSN:0006-3592    

DOI:10.1002/bit.260231102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractRelatively poor SCP production (4.2 mg/L h) was obtained usingC. cellulolyticumand ground aspen wood treated with steam at atmospheric pressure for 1 h. The percentage of protein in the final product increased to 21.4% at a specific growth rate of 0.15 h−1when the wood sample was treated with steam at a higher pressure (280 psig for 4 min) according to the "Stake" process. Alkali treatment (10% and 15% w/w at 121°C for 30 min), known to solubilize hemicelluloses and some of the lignin, gave intermediate results. More complete delignification of wood using NaClO2increased the protein composition in the final product to 37.9%, at a specific growth rate of 0.19 h−1. Cellulose utilization was lowest (12.4%) in the case of the wood treated with steam at atmospheric pressure; it was higher at 75.3 and 78.5% for wood treated with NaOH at 10 and 15% w/w levels, respectively. The cellulose utilization was highest (90%) for wood treated with Na

ISSN:0006-3592    

DOI:10.1002/bit.260231103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe effects of aeration on the flow characteristics of water in a glass pilot‐scale airlift fermentor have been examined. The 55‐L capacity fermentor consisted of a 15.2‐cm‐i.d. riser column with a 5.1‐cm‐i.d. downcomer tube. It was found that the average bubble size diminished with increased aeration. Typically, average bubble sizes ranged from 4.32 mm at a superficial gas velocity of 0.64 cm/s to 1.92 mm at 10.3 cm/s. A gas holdup of 0.19 was attained with superficial gas velocities (vs) on the order of 10 cm/s, indicating the highly gassed nature of the fluid in the riser section of the fermentor. Circulation velocities of markers placed in the fermentor decreased with increasing aeration rates due to increased turbulence and axial liquid back mixing within the riser section. Actual volumetric liquid circulation rates remained relatively constant (0.36–0.49 L/s) for values of (vs) up to 10 cm/s. Based on theoretical calculations, the ascending velocity of bubbles in a swarm reached 54 cm/s in the range of (vs) v

ISSN:0006-3592    

DOI:10.1002/bit.260231104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractCitric acid fermentation on pilot plant scale was studied, using two strains ofAspergillus nigerof different productivity. Growth and product formation were analyzed from a high number of data points. Several phases could be distinguished which were described by a sequence of logarithmic, cube‐root, and linear equations. Growth and product formation could be related by a modified Luedeking‐Piret equation, taking into consideration a lag time for the organism to shift to shift into the physiological state ready for product formation. The observed differences in productivity of the two strains are reflected by the different non‐growth‐associated terms of the equation. In light of these findings the classical "type II fermentation" is redefined as a mixed type–resembling type I during trophophase and type III during i

ISSN:0006-3592    

DOI:10.1002/bit.260231105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractA kinetic model for the reaction sequence catalyzed by coimmobilized invertase and glucose oxidase with a sucrose substrate in a tubular reactor has been developed. The computerized mathematical model employs and orthogonal collection technique for solving oxidase were coimmobilized in poly(2‐hydroxyethlmethacrylate) gels and used in a continuous flow packed‐bed tubular reactor system. In addition to describing the development of the kinetic model, this article compares experimentally determined reactor effluent concentrations for various sucrose feed solutions to those predicted by the model. Variations between experimental and predicted reactor effluent concentrations were found to be on the micromolar level for sucrose feed concentrations as low as 1.3

ISSN:0006-3592    

DOI:10.1002/bit.260231106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe mathematical model for the reaction sequence catalyzed by immobilized invertase and glucose oxidase discussed in the preceding article has been used successfully to duplicate experimental findings. In addition, it has been used as a tool for the simulation and prediction of effects derived from alterations to system‐related and gel‐related parameters. The effects of gel diffusivity on the overall conversion of sucrose substrate to reaction products was investigated through use of this model. Changes in the enzyme loading within a gel and the results of varying the ration of invertase activity to glucose activity were also evaluated. Through use of concentrations of the molecular species determined at the collocation points within a gel particle and in the bulk liquid phase, an estimate of the thickness of the diffusion boundary layer around the gel particle was determined which was in close agreement with values obtained from classical mass transfer relationships. For most of this study, the enzymes were coimmobilized within the same polymeric matrix. However, a number of tests were run with the enzymes immobilized individually and placed in separate reactors in a sequential reactor system. The experimental results from these tests were duplicated successfully by means of the model with little modification to the basic computer program. Such an example illustrates the potential flexibility of the model and its overall versatil

ISSN:0006-3592    

DOI:10.1002/bit.260231107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractFurther work on a thermophilic rennet synthesized by a thermophilic actinomycete is reported. It was produced by growth in fermentor of 50‐or‐200‐L volume and was purified by membrane filtration of a cell‐free supernatant and then molecular filtration and ion exchange chromatography. Its stability under various conditions was determined: The enzyme is a true rennet requiring calcium ions for activity. Experiment shows that it resembles neither pepsin, trypsin, nor chymotrypsin. It is freeze‐labile with a molecular weight of 9700 from amino acid composition. When skim milk powder was added to the growth medium, a rennet with different properties was

ISSN:0006-3592    

DOI:10.1002/bit.260231108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractFor the purpose of a rational design for an automatic feedback control system incorporating a porous Teflon tubing sensor in semibatch culture, steady‐state mass‐transfer characteristics of tubing sensors have been investigated theoretically and experimentally, and also dynamic responses have been studied experimentally. A distributed mathematical model for steady‐state diffusion has been solved numerically and its solution has been shown as useful for the sensor design. The overall mass‐transfer resistance of radial diffusion has been shown to be the sum of external liquid‐film mass‐transfer resistance and membrane diffusion resistance. The steady‐state experiments using ethanol dissolved in water revealed that its transfer into the tubing was controlled by the molecular diffusion within the tubing‐wall membrane. Oxygen transfer from external water into the tubing was shown experimentally to be controlled by the liquid‐film resistance outside the tubing. In general, the radial mass transfer of a substance having a small Henry's constant is controlled by the liquid‐film resistance.The response of the tubing sensor‐detector‐recorder system for the stepwise addition of ethanol into the external water could not be represented by a simple combined system of the first‐order delay with lag time. The responses depend on the characteristics of the tubing as well as flow rate of the carrier gas, etc., but they were quite excellent in all

ISSN:0006-3592    

DOI:10.1002/bit.260231109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractAn automatic feedback control system incorporating a porous Teflon tubing sensor was developed and a strain of yeast was cultivated semibatchwise in mineral salt medium by feeding pure ethanol as the sole carbon source. In the control system, The ethanol concentration was continuously measured by the porous Teflon tubing sensor combined with a flame ionization detector, and its output signals were furnished to an automatic feed controller which controlled an ethanol feed pump so that deviations from the set level of ethanol concentration might be corrected. The controller was constructed on the basis of proportional‐differential negative feedback control of which the proportional sensitivity and differentiation constants were estimated from the dynamic mass balance of ethanol. Precise measurement of temperature and compensation of the detector output signals for temperature fluctuations of culture broth were necessary to achieve good control. Cultivation experiments were carried out with three levels of concentrations: 102, 103, and 104ppm. The relative deviations of the concentrations were less than ±0.5% for the 103‐ and 104‐ ppm levels but a little offset arose for the 102‐ppm levels. The growth of cells was at first exponential and then almost linear when the dissolved oxygen concentration dropped cons

ISSN:0006-3592    

DOI:10.1002/bit.260231110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractLignocellulosic plant materials were treated with various swelling agents and exposed to γ radiation from60Co or137Cs. At dosages of 50 Mrad or above, lignocellulosic materials were extensively degraded and solubilized in water. Addition of water, NaOH, or H2SO4to the substrate increased the degree of solubilization. Complete solubilization was achieved for samples of sugarcane bagasse, newspaper, cotton linters, cotton cloth, sawdust, and α‐cellulose powder. About 35% total sugar and 5% reducing sugar per dry weight of sugarcane bagasse could be obtained by this method. Most of the soluble carbohydrates seemed to be disaccharides or larger molecules and glucose degradation products. Solubilization of cellulose was dosage dependent and although the rate of solubilization was increased by adding alkali, released sugar was further decomposed by the alkali and by high dosage of radiat

ISSN:0006-3592    

DOI:10.1002/bit.260231111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY