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  • 1
    Electronic Resource
    Electronic Resource
    Hydrolysis and thermophilic anaerobic digestion of sewage sludge and organic fraction of municipal solid waste (1999)
    Springer
    Bioprocess engineering 20 (1999), S. 553-560 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An attempt is presented and discussed to adapt a well-known process successfully employed in the U.S.A. for the simultaneous treatment of the organic fraction of municipal solid waste (MSWOF) and sewage sludge to the particular situation of water works in Italy. It consists of preliminary domestic grinding of MSWOF, its discharge into the sewer, screening, and final digestion of the resulting residue together with sewage sludge. In order to avoid extension work of the present activated sludge sections necessary to face the organic load increase, a fine screening is necessary, while the efficiency of anaerobic digestion can be improved by shifting the system from mesophilic (37 °C) to thermophilic (55 °C) conditions. The effects of thermal, chemical, and biological pretreatments of both MSWOF and sewage sludge on methane, carbon dioxide, and biogas productions are investigated either separately or jointly. During these pretreatments, volatile suspended solid (VSS) concentration remarkably decreased while soluble chemical oxygen demand (COD) increased as the result of the progressive hydrolysis of the polymeric materials present in the feed. Finally, the kinetic parameters of the hydrolysis of these materials are estimated and compared in order to provide useful information on the factors limiting the anaerobic digestion as well as to suggest the best way to carry out the process on a large scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004490050628
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  • 2
    Electronic Resource
    Electronic Resource
    Anaerobic digestion of the vegetable fraction of municipal refuses: mesophilic versus thermophilic conditions (1999)
    Springer
    Bioprocess engineering 21 (1999), S. 371-376 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The phenomena limiting the anaerobic digestion of vegetable refuses are studied through batch tests carried out using anaerobic sludge previously selected under either mesophilic (37 °C) or thermophilic (55 °C) conditions. The compositions of the hydrolysed cellulosic and hemicellulosic fractions of these materials are simulated by starch and hemicellulose hydrolysates, respectively. Non-hydrolysed mixtures of vegetable waste with sewage sludge are used to ascertain whether the hydrolysis of these polymeric materials is the limiting step of the digestion process or not. The experimental data of methane production are then worked out by a first-order equation derived from the Monod's model to estimate the kinetic rate constant and methane production yield for each material. Comparison of these results shows that passing from mesophilic to thermophilic conditions is responsible for a slight deceleration of methane production but remarkably enhances both methanation yield and methane content of biogas. The final part of the study deals with the fed-batch digestion of the same residues in static digester. Working under thermophilic conditions at a loading rate threshold of 6.0 gCOD/l · d, the hemicellulose hydrolysate ensures the highest methane productivity (60 mmolCH4/l · d) and methane content of biogas (60%), while unbalance towards the acidogenic phase takes place under the same conditions for the starch hydrolysate. The intermediate behaviour of the non-hydrolysed mixture of vegetable waste with sewage sludge demonstrates that hemicellulose hydrolysis is the limiting step of digestion and suggests the occurrence of ligninic by products inhibition on methane productivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004490050689
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of a reactor for glucose isomerization to fructose by immobilized glucose isomerase with continuous enzyme renewal (1997)
    Springer
    Biotechnology techniques 11 (1997), S. 99-103 
    Details
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Two different dispositions of laboratory-scaled columns have been tested to simulate the isomerization of glucose to fructose in a mobile bed reactor where exhausted immobilized glucose isomerase is continuously renewed. If the simulation columns working at 65°C are arranged in parallel and connected to a section for final enzyme exploitation at 75°C, a syrup with constant composition can be produced, at relatively constant total throughput, by feeding the individual columns at flow rate decreasing according to the enzyme decay profile and following a programmed disphased mode of operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018420623190
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Cadmium, Zinc, Copper, Silver and Chromium(III) removal from wastewaters by Sphaerotilus natans (1998)
    Springer
    Bioprocess engineering 19 (1998), S. 197-203 
    Details
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Living cells of Sphaerotilus natans are used for heavy metal's (Cd, Zn, Cu, Ag, and Cr) removal from aqueous solutions simulating the polluting power of acid industrial wastewaters. At low metal concentrations (〈25 mg/l) this microorganism is able to remove within 8–15 days Cd, Zn, Cu, and Ag with excellent yields (from 81 to 99%) often increasing with starting metal concentration. The yield observed for Cr(III) removal, never exceeding 60%, is not appreciably influenced by the starting biomass level; in addition, the time necessary to reach the equilibrium concentration is always remarkably longer (〉30 days) than for the other metals. At much higher concentrations, the removal of all the metals is strongly affected in terms of both yield reduction and increase in the time necessary to reach the equilibrium concentrations. Under the hypothesis of mass transfer limitation, the kinetic study of batch runs suggests that metal diffusion from the bulk to the surface of S. natans clumps could be responsible not only for the simple biosorption of the tested metallic micronutrients or abiotic metals, but even for the cell penetration by ions of biological significance, like Mg2+ and Fe3+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009011
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Continuous alcohol fermentation in an immobilized cell rotating disk reactor (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 761-768 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The increasing interest in alcohol fermentation over these last years because of the energy crisis has been demonstrated by an increase in scientific research. After a brief analysis of the main results of the literature in the field of alcohol fermentation reactors, the use of a new type of immobilized cell reactor [the rotating biological surface (RBS) reactor] was studied. As is well known, the RBS reactor is a form of fixed-film reactor and can be described as a dynamic trickling filter. Our experimental apparatus employed a spongy material to trap the yeast cells on the disks. The results of fermentations carried out in the RBS reactor working in batch, in continuous with cell support, and in continuous without cell support have been presented in order to compare the different productivities and to assess the performance of the RBS immobilized cell reactor. An ethanol productivity of 7.1 g/L h was achieved in the RBS-ICR at a dilution rate of 0.3 h-1, 2.5 times higher than the maximum productivity obtained in the RBS reactor without support at a lower dilution rate. The adoption of a spongy material as a cell immobilizer, combined with the use of the RBS reactor, enhances the particular advantages of both systems.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270602
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Selection of hemicellulosic hydrolysate pretreatments and fermentation conditions to stimulate xylitol production by ethanol-producing yeasts (1996)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 16 (1996), S. 133-144 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Xylitol production from hardwood hemicellulosic hydrolysates by well-known ethanol-producing yeasts was stimulated through an experimental schedule including pretreatments of the hydrolysate, the choice of the best xylitol producer and the selection of the optimum fermentation conditions. The xylitol or ethanol yields obtained on consumed xylose demonstrated that their production was stimulated under completely different conditions, as to be expected by the fact that these catabolites are the final products of different metabolic pathways. In particular, the catabolism of Pachysolen tannophilus, that is the best ethanol producer from this natural substrate, could be targeted towards xylitol rather than towards ethanol production by ensuring a strongly reducing environment through a suitable pretreatment of the hydrolysate. The final removal of fermentation inhibitors by adsorption onto highly adsorbing substances allowed a further 20% xylitol yield increase.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370160207
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    Paper (German National Licenses)
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