摘要:

AbstractDifferences in the concentration and retention of137Cs by unicellular diatoms, filamentous green algae, and filamentous blue‐green algae were demonstrated under both batch and continuous‐flow culture conditions.137Cs concentration factors were generally higher by a factor of 2 in batch tests than in continuous flow tests. In retention studies,137Cs was desorbed more rapidly from algae under continuous‐flow conditions. Studies with blue‐green algae indicate that137Cs concentrations in the various species were more closely related to the surface‐to‐volume ratios of algal cells than to the systematic relationships of the three species. Continuous‐flow studies indicated no differences among three species of filamentous green algae in the concentration of137Cs,65Zn, and85Sr. However, the average concentration factors of the radionuclides were considerably different: 3800 for65Zn, 460 for137Cs, and 230 for85Sr. These radionuclides were rapidly desorbed following the transfer of algae to nonradioactive media. The desorption rate was inversely related to the conce

ISSN:0006-3592    

DOI:10.1002/bit.260090402

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

年代:1967

数据来源: WILEY

摘要:

AbstractEutrophication, or fertilization, has become a major water pollution problem associated with the discharge of mineral‐rich sewage eflluent. A metabolic process to remove dissolved phosphate from sewage through the action of sewage microorganisms is under development. The process, unlike other proposed solutions to the problem, would not require tertiary treatment of the sewage. Laboratory studies have produced promising data. Early reports from municipal sewage treatment plants confirm the expectation that the process may be feasible for widespread us

ISSN:0006-3592    

DOI:10.1002/bit.260090403

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

年代:1967

数据来源: WILEY

摘要:

AbstractIn bacterial extraction of copper from low‐grade copper sulfide ores, at least three contributions are made byThiobacillus ferrooxidans.They are: (1) enzymatic oxidation and consequent solubilization of insoluble sulfides; (2) regeneration of ferric lixiviant for chemical oxidation and solubilization of insoluble sulfides; and (3) partial fixation of externally introduced iron in the ore. Although it is not possible at the present time to measure each of these contributions separately, it is possible to measure the combined contributions. Such measurements reveal a strong dependence of extraction efficiency on various physical, chemical, and biological factors. The following physical factors may affect the rate of bacterial copper extraction: particle‐size of ore, oxygen and carbondioxide supply, oxidation‐reduction potential, pH, temperature, adsorption and ion exchange capacity of ore, and surface tension effects. The following chemical factors may influence the rate of copper extraction: the mineralogy of the ore, the nature of the gangue, the distribution of the sulfide minerals in the host rock, the external supply of ferrous or ferric iron, and the availability of inorganic and organic nutrients. Finally, the following biological agents in addition toT. ferrooxidansmay influence the rate of copper extraction: fungi, protozoa,Thiobacillus thiooxidans, and heterotrophic bacteria. Proper control of these various factors is essential for efficient bacterial extraction of copper from low‐grade ore. It is recognized that the foregoing environmental factors also influence chemical copper ext

ISSN:0006-3592    

DOI:10.1002/bit.260090404

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe results of our survey of several mining operations have shown in every instance typicalT. ferrooxidansbacteria to be present in the leaching solutions. The numbers of bacteria found are in general what, one would expect considering the chemical reactions occurring in these processes. A major difficulty is encountered when one considers the complex and unknown series of events which occur, as the bacteria‐bearing, acidic, ferric‐ion solution penetrates the massive ore dumps. Laboratory studies show microbial activity to be the major cause of rapid solubilization of copper sulfide ores. Field studies suggest that microbial activity cannot explain all observations in a typical leaching operat

ISSN:0006-3592    

DOI:10.1002/bit.260090405

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe cultivation of aerobic, methane‐utilizing, microbial cells by submerged culture techniques, in an entirely mineral salts medium, with a view to their use as an edible protein source is discussed. Particular emphasis is placed on the potentially explosive nature of gaseous mixtures containing methane and oxygen. The experiments described investigate if fully safe operation at all times, by oxygen concentration control, is possible in agitated and sparged batch fermentors. Appreciable wastage of methane is prevented by gaseous‐phase recirculation. It is concluded that fully safe operation is possible, cultures being able to grow exponentially without substrate limitation by the gaseous‐phase nutr

ISSN:0006-3592    

DOI:10.1002/bit.260090406

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

年代:1967

数据来源: WILEY

摘要:

AbstractA method for the control of dissolved oxygen tension in growing microbial cultures is described. The apparatus consists of a motor‐driven air sparge pipe which may be lowered or raised to give a variable point of entry of the air stream into the culture liquid and hence a variable gas dispersion and gas–liquid contact time. Control of the sparge pipe position is by means of a feedback control loop consisting of a dissolved oxygen probe, an on/off controller, and a reversing electric motor which drives the sparge pipe. The difficulty presented by the relatively slow response of the oxygen probe has been overcome by incorporating an adjustable rate of control act

ISSN:0006-3592    

DOI:10.1002/bit.260090407

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

年代:1967

数据来源: WILEY

摘要:

AbstractA rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient,kLa, in fermentation systems. The method consists of tracing the dissolved O2concentration of the fermentation broth during a short interruption of the aeration. The O2concentration trace thus obtained can be analyzed to determine the values ofkLa. Additional experiments on prolonged O2starvation, carried out to find the limitation of the technique, suggest that O2uptake rate will vary if a prolonged (2–10 min.) O2starvation occur

ISSN:0006-3592    

DOI:10.1002/bit.260090408

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

年代:1967

数据来源: WILEY

摘要:

AbstractInterfacial phenomena are directly involved in the adhesion of a strain ofChlorella, a unicellular alga, to glass surfaces in simple ionic solutions. The principal mechanisms governing the adhesion appear to be electrostatic interaction between electrical double layers and various specific surface interactions resulting from surface heterogeneity and ion adsorption. Under most conditions the algal cells and glass surfaces have negative zeta potentials, and adhesion to glass will not occur; but if, for example, FeCl3is added to an algal–glass system immersed in 0.05MNaCl, the algal and glass surfaces will possess very different zeta potentials, and adhesion will be strongest under those conditions which produce the greatest, difference in zeta poentials. Prior pretreatment and usage of glass apparatus greatly affect the glass zeta potentials and the adhesion of algal cells to glass. An apparatus for measuring a relative set of numbers representing the force of adhesion of algal cells is describe

ISSN:0006-3592    

DOI:10.1002/bit.260090409

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

年代:1967

数据来源: WILEY

摘要:

AbstractAn electronic apparatus is described that permits rapid determination of the concentration and size distribution of bacteria in electrolyte suspensions by a resistance method. The resulting size‐concentration distribution may be displayed on an oscilloscope and recorded with anX–Yplotter and an electric typewriter‐tape punch unit. The paper tape is analyzed with a computer program. Comparisons are made between electronic measurements of bacterial cell concentration and size distribution and values obtained by other methods. Effects of heat‐killing and disruption of the cell membrane on the electrical counting characteristics of the organisms are di

ISSN:0006-3592    

DOI:10.1002/bit.260090410

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

年代:1967

数据来源: WILEY

摘要:

AbstractA device is described based on the principle of a simple analog computer which gives an exact determination of the moment at which the heat energy supply should be interrupted to attain a chosen sterilization effect. The temperature of the medium to be sterilized is measured and at temperatures above 100°C. the dependence of the thermal destruction coefficient of microbial spores on temperature is simulated. This variable is integrated with respect to time and the value of this integral at any given moment corresponds to the sterilization effect, at that moment. The device is also fitted with an extrapolator which evaluates, depending on the instantaneous temperature of the medium, the value of sterilization effect which will be produced during the cooling of the medium after the interruption of the heat, energy supply. The total sterilization effect, in the course of the cycle, is continuously and automatically evaluated as a sum of the integrated sterilization effect and of data supplied by the extrapolator. At the moment when this total sterilization effect attains the prescribed value, the device gives a signal for the interruption of the heat energy supply. The value of the sterilization effect is adjustable within broad limits and its evaluation is performed without substantial simplifying assumptions. By the use of this device an exact scale‐up method for sterilizing media is achieved, yielding at the same time accurate reproducibility of media sterilization. An automatic control of the sterilization cycle is also possible by means of the devi

ISSN:0006-3592    

DOI:10.1002/bit.260090411

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

年代:1967

数据来源: WILEY