摘要:

AbstractThe modeling of biological wastewater treatment processes has received much attention over the past ten years. Efforts are underway to develop a unified model for these processes which will greatly aid in the design and operation of wastewater treatment facilities. This paper presents a philosophical discussion of model building strategies augmented by a discussion of statistical problems associated with model parameter estimation and model discrimination. This discussion further illustrates with actual data, that goodness of fit is not a sufficient condition for model acceptance. Numerous rival models are examined to illustrate this point. In order to verify a model or to discriminate between rival models, they must be “Put in jeopardy.” If this attitude is not employed in model building efforts, important discrepancies in the proposed model may go undetec

ISSN:0006-3592    

DOI:10.1002/bit.260160902

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

年代:1974

数据来源: WILEY

摘要:

AbstractHighly charged water‐soluble conjugates of amyloglucosidase with a copolymer of ethylene‐maleic acid or styrene‐maleic acid were prepared and adsorbed on DEAE‐cellulose and other cationic resins. Negatively charged enzyme conjugates were also obtained by means of succinylation. The polyanionic conjugates of amyloglucosidase adsorbed on the cationic carriers show higher temperature stability than the native enzyme adsorbed on the same carriers under the same experimental conditions. The insoluble enzyme conjugate‐carrier complexes could be reused and retained their full activity while working continuously for three weeks. The application of the insoluble enzyme preparations with the above characteristics which could possibly satisfy the requirements for industry are

ISSN:0006-3592    

DOI:10.1002/bit.260160903

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe consideration of fermentation principles in the treatment of industrial and sanitary waste waters leads to substantial process improvements. In particular, the rate of reaction can be improved by several fold by establishing the proper environmental conditions for microbial growth in a fermentation system. Recent work on the concentric cylinder air lift has shown it to be an economical fermentor with many advantages over conventional fermentors. An attempt to improve the economical performance of this system led to the development of the thin channel rectangular air lift fermentor. This was based upon a theoretical analysis of performance parameters. The analysis indicates decreased bubble coalescence, increased bubble entrainment, decreased power costs, increased mass transfer coefficients, and decrease capital costs. Experience using a prototype thin channel rectangular air lift system with sanitary and industrial waste‐water treatment systems has demonstrated exceptionally high rates of BOD removal at low operating and capital cost

ISSN:0006-3592    

DOI:10.1002/bit.260160904

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

年代:1974

数据来源: WILEY

摘要:

AbstractEfforts were made to eliminate the influence of other factors as far as possible in order to obtain reliable results on the effects of oxygen on the growth of baker's yeast. A cultivation method is presented which permits the study of the effects of aeration intensity under conditions where the influence of catabolite repression is eliminated. A completely synthetic medium with glucose as the only carbon and energy source is also described.The capacity of yeast to perform aerobic metabolism varies when cultivated under different intensities of aeration. A clear maximum is observed for growth with 10% oxygen in the aerating gas mixture. Under conditions where catabolite repression does not function yeast has the potential for oxidative metabolism even under oxygen‐limited growth. The main agent controlling the ability of yeast to support growth using only the oxidative metabolism is the available oxygen.At high oxygen tensions the metabolism is disturbe

ISSN:0006-3592    

DOI:10.1002/bit.260160905

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

年代:1974

数据来源: WILEY

摘要:

AbstractWhen the effect of catabolite repression is eliminatedSaccharomyces cerevisiaeprefers an aerobic metabolism. The potential for completely aerobic catabolism exists even in circumstances where its action is limited by the oxygen available. When the oxygen absorption in the medium is adequate, yeast uses a solely oxidative metabolism for energy‐yielding reactions. The changes observed in the activity of malate dehydrogenase can be described as a function of two isoenzymes, both of which are affected by oxygen; the isoenzyme participating in the glyoxylate cycle shows variations in activity similar to that observed in isocitrate lyase. NAD‐linked glutamate dehydrogenase activity roughly follows that of malate dehydrogenase and isocitrate lyase; in cultivations with the same growth rate the NADP‐linked dehydrogenase is insensitive to the oxygen level. The cytochromes aa3, b, and c have a clear maximum at low oxygen tension, the most sensitive being cytochrome aa3. The imbalance between cytochrome c:oxygen oxidoreductase activity and the amount of cytochrome aa3, and the correlation observed between respiration rate and the activities of cytochrome c oxidase and NADH2:cytochroine c oxidoreductase are discussed. Methods used for estimation of cytochromes are com

ISSN:0006-3592    

DOI:10.1002/bit.260160906

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

年代:1974

数据来源: WILEY

摘要:

AbstractAn intracellular, thermostable, neutral α‐galactosidase (α‐D‐galactoside galactohydrolase EC 3.2.1.32) was produced in pilot plant quantities from a strain ofBacillus stearothermophilus. The organism was cultured at 50°C in a soluble neutral medium containing water extract of soybean meal (3%) and 0.5% yeast extract. The enzyme biosynthesis was inducible and sensitive to catabolite repression. After autolysis of the cells, the α‐galactosidase was selectively and quantitatively complexed from clarified beer directly onto DEAE Sephadex; and enzyme‐rich fractions were batchwise eluted with an increasing gradient of NaCl solutions. The eluates were given two consecutive isopropyl alcohol precipitations, and the aqueous solutions of the second precipitate were dialyzed and lyophilized. Final product activity recovery was 72% based on the crude fermentation beer. Best specific activity was 5.2 u/mg protein. Further laboratory purification (DEAE Sephadex and Bio‐Gel P200) yielded a product with 14

ISSN:0006-3592    

DOI:10.1002/bit.260160907

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe death kinetics of a strain ofSaccharomyces cerevisiaewere studied in an industrial scale spray drier. In solution studies, the death kinetics of yeast was found to be comparable to pathogen destruction. From the studies in drying of yeast a prediction of a 4 log cycle decrease in viable cells of pathogens could be made for normal processing conditions. This should insure the safety of spray‐dried foods unless after contamination occurs. It was found that during drying, although the rate of death is high, the activation energy is greatly decreased over that of death in aqueous solution (reduction from 130 kcal/mole to 5 kcal/mole). The reduction inEamay be attributed to the thermodynamic compensation phenomenon in which the resulting negative entropy of reaction acts to protect the cells through a water–protein interaction. However, the possibility of a change in death mechanism cannot be precluded. Overall, these results suggest the danger in extrapolating death kinetics to high temperat

ISSN:0006-3592    

DOI:10.1002/bit.260160908

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

年代:1974

数据来源: WILEY

摘要:

AbstractA tubular loop batch fermentor has been designed and constructed, and was found to behave in a similar manner to a conventional stirred tank reactor. It appeared that foaming could be greatly reduced as no air ever encountered the impeller. The fluid mechanics of pipe flow are considerably simpler than tank flow patterns. On this basis a design procedure for a large scale tubular fermentor was outlined, which had considerable advantages over the more complex scale‐up problems of a tank fermento

ISSN:0006-3592    

DOI:10.1002/bit.260160909

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

年代:1974

数据来源: WILEY

摘要:

AbstractAn electronic particle counter has been used to estimate the disintegration by freeze‐pressing baker's yeast. A counter threshold level which just yielded the maximum count for intact cells was selected. The conductivity of the suspending medium was chosen such that maximum counts were obtained. Under these conditions, the electronic counts agreed well with the visual counts. At a certain threshold level the maximum count was obtained at a lower resistivity (higher conductivity) in the suspending solution with the freeze‐pressed suspension than with untreated cells, indicating that damage to the permeability barrier may occur without disruntion of the cell envelope.Fresh baker's yeast cells do not behave as nonconducting particles. This has to be taken into account when volume determinations with electronic particle counters are perfor

ISSN:0006-3592    

DOI:10.1002/bit.260160910

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

年代:1974

数据来源: WILEY

摘要:

AbstractSystem response data for step changes in input tracer concentration have been obtained for two different impeller agitated continuous flow mixing systems containing aqueous polysaccharide solutions. The vessel volumes were 1.6 and 10.9 liters. Polysaccharide concentration, dilution rate, and impeller speed were varied according to a plan devised using dimensional analysis and assuming that bulk motion is the predominant mass transport mechanism in the system. The data show that this is not true and that serious errors may occur if scale‐up calculations are based on assuming that bulk motion predominates. Under the operating conditions used, perfect mixing was not observe

ISSN:0006-3592    

DOI:10.1002/bit.260160911

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

年代:1974

数据来源: WILEY