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  • 1
    Electronic Resource
    Electronic Resource
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of chemical reactor engineering 5.2007, 1, A22 
    ISSN: 1542-6580
    Source: Berkeley Electronic Press Academic Journals
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, the use of a natural material, sawdust, in a fluidised biofiltrer has been considered. The performance of the biofiltration of ethanol and toluene was estimated in the presence of the native microorganisms of the material and also after the addition, and a period of acclimatization, of external microorganisms. Modifications of the physical and biological characteristics of the material were studied in order to better understand the process. The influence of biofilter shutdown periods was also considered to evaluate the effect of a period of inactivity on subsequent performances.This study shows that a significant degradation of the pollutants is obtainable provided that the following steps are performed: seeding with activated sludge, introduction of nutrients, and control of the changes in the material characteristics and the bed moisture.During the operation of the fluidized bed biofilter, the moisture of the bed had an important effect on the biofilter performance, but was rather difficult to control because of its dependence on the ambient and inlet air temperatures, which changed during the day and the seasons. During the tests with the batch of sawdust particles used as delivered without any sludge enrichment, a reduction in abatement performances was measured with time. In the case of ethanol alone, for a concentration of 0.02 g.m-3, abatement decreased from 24% to 18% then to 7%. The partial or complete addition of sawdust particles previously activated with sludge significantly enhanced the performance of the biofilter, both for ethanol and toluene pollution. Abatements of ethanol of 85% and 60% were achieved when the sawdust particles were activated by sludge. In contrast, a 5-week shutdown of the reactor produced a decrease in abatement, either by a loss of microorganism efficiency during their "starvation" or by their destruction.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of chemical reactor engineering 6.2008, 1, A9 
    ISSN: 1542-6580
    Source: Berkeley Electronic Press Academic Journals
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work deals with microbial growth onto filter media and focuses on the ability of microbial communities to proliferate onto filter media. Two microorganism types are studied: microorganisms from activated sludge of wastewater treatment plant (SM) and a toluene specific consortium (TSC). The filter media considered for this study contain activated carbon fibres (ACF), combined volatile organic compounds (VOC), particles treatment purposes, activated carbon fibres felt (ACFF) and activated carbon and cellulose fibres felt (AC2F2). Using a static growth procedure during 10 days under 100 % relative humidity, artificially contaminated filters are submitted to microbial colonisation. The final concentration of microorganisms per gram of filter have been assessed using a method developed in the lab, based on filter protein content assay. The average surface charge of inocula and filter's fibres are measured to assess the influence of microorganisms adhesion on contamination. The influence of soot particles on TSC proliferation onto AC2F2 filter is then studied. Zeta measures enable the assessment of the implication of soot in microorganisms adhesion onto filter fibres. Consequences of microbial contamination on filter permeability and downstream particles released have then been assessed in a filtration device. Results demonstrate a better resistance of AC2F2 to microbial colonisation. However, SM have more difficulties to proliferate on ACFF than TSC, whereas SM colonise easier AC2F2 than TSC. Charge surface assay has defined an optimal electrostatic compatibility for TSC and AC2F2 and a minimum for SM and ACFF. When soot is added to TSC solution before introduction in AC2F2, high contamination shapes were observed whereas only a slight one occur without soot addition. Zeta potential measures show favourable charge conditions for adhesion of soot on AC2F2 fibres and TSC on soot particles. The soot may thus have played an interface role in microbial adhesion onto media. This means that electrostatic compatibility between particles is a good approach for assessing microbial adhesion onto filters but could not explain the whole mechanism of microbial proliferation. Other parameters like nutrition preferences are certainly involved. The contamination have induced filter characteristics modification. Permeability have decreased until 20 % with microbial concentration. Colonised filters have released up to 450 microbial particles/cm3. Such a release was only observed when AC2F2 was contaminated with fungi using spore as the reproduction vector (inoculum containing TSC and soot).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 115 (1994), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A study of cell-wall site interaction of uranyl ion adsorbed by non-proliferative suspensions of Mycobacterium smegmatis at pH 1 has been carried out using extracts of arabinogalactan-peptidoglycan and phospholipids obtained from whole cells treated under sorption conditions. Evidence for binding of UO22+ by constituent P-lipids was provided by comparative 31P-NMR and IR spectroscopic measurements of the isolated wall fractions and of the model complex uranyl-phosphatidyl inositol.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-8773
    Keywords: Mycobactin S ; Group III cations ; Optical spectra ; Molecular modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The interaction of cations of group IIIb elements (Sc, Y, La) with mycobactin S in ethanol leads to the formation of 1:1 complexes which closely resemble the known aluminium compound with respect to ultraviolet absorption and fluorescence emission spectra. Determination of molar stoichiometry by spectrophotometry shows that this method can be conveniently applied to the estimation of purity in mycobactin samples. Hydrolytic dissociation measurements based on aqueous extraction of the labelled complexes in heterogeneous phase indicate a pronounced gradation in cationbinding stability, which increases from La (rapid and complete dissociation) to Sc (≈ 24% dissociation under similar conditions). The observed properties of the complexes are rationalized by semi-empirical model calculations, which suggest that ionic radius effects resulting from interaction of the IIIb cations with mycobactin S would not favour octahedral coordination of these elements as in the stable Fe(III) complex.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 39 (1993), S. 413-417 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Adsorption measurements of several actinide [thorium (Th), uranium (U)] and lanthanide [lanthanum (La), europium (Eu), ytterbium (Yb)] cations by Mycobacterium smegmatis showed that sorption kinetics followed a three-phase pattern. For 5% (w/w) bacterial suspensions at pH 1, maximum cation biosorption per gram dry biomass corresponded to 170 μmol Th4+ and 187 μmol UO inf2 sup2+ . Adsorption of all cations studied obeyed the Brunauer-Emmett-Teller isotherm, which assumes multilayer binding at constant energy. Plots for the Scatchard model showed the existence of at least two types of cation complexation site, with strong and weak affinity and negative cooperation. Th4+ was preferentially adsorbed with respect to the other cations, although all species appeared to compete for the same sites independently of bacterial viability. Adsorption of these cations was accompanied by partial release of magnesium from the cell wall, indicating that exchange reactions occurred at magnesium (Mg)-bonding sites.
    Type of Medium: Electronic Resource
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