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  • 1
    ISSN: 1432-0495
    Keywords: Organic compounds ; Groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In situ microcosms were successfully used to study the degradation of a range of organic compounds in two pristine aquifers, one aerobic (Vejen) and one anaerobic (Villa Farm). Degradation and sorption behavior in the laboratory column microcosms packed with Villa Farm sediment was very similar to that in the in situ microcosms. However, when the columns were packed with quartz and equilibrated with aerated Villa Farm groundwater, behavior mirrored that at Vejen, indicating that oxygen rather than sediment or groundwater composition was the critical parameter. The aromatic and polyaromatic compounds (benzene, toluene,o-xylene, naphthalene) degraded under aerobic conditions only. The organochlorine compounds (trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,4-dichlorobenzene and 1,2-dichlorobenzene) showed little or no sign of degradation either aerobically or anaerobically. Interpretation of the data was complicated by strong sorption to the Villa Farm sediment but tetrachloromethane, nitrobenzene, ando-nitrophenol appeared to degrade under anaerobic conditions only. Phenol degraded rapidly under both sets of conditions.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 44 (1996), S. 823-830 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Changes in the chemical composition of organic compounds in total activated sludge, activated sludge extracellular polymeric substances (EPS), and sludge bulk water during anaerobic storage (12 days) were studied. The background for the study was that anaerobic storage of activated sludge, which often takes place at wastewater treatment plants before dewatering, causes a deterioration of the dewaterability. The reasons are not known at present, but may be related to changes in exopolymer composition of the flocs. The results showed that a fast decrease in total sludge protein and carbohydrate took place within 3 days of anaerobic storage as a result of degradation processes, which accounted for approximately 20% of the organic fraction. The amount of uronic acids and humic compounds remained almost constant in the sludge. The EPS were extracted from the floc matrix using a cation-exchange resin. In the EPS matrix a similar initial (2–3 days) degradation of proteins and carbohydrate took place, whereas the content of DNA and uronic acids showed minor changes. The extractability of humic compounds increased during the first 3 days of storage. No changes in extractability of the carbohydrate were observed. A fraction of the EPS protein was found to be difficult to extract but was observed to be degraded during the anaerobic storage. The EPS composition was further characterized by high-performance size-exclusion chromatography analysis obtained by on-line UV detection and post-column detection of proteins, carbohydrates, humic compounds and DNA. Four fractions of polysaccharides were found, of which only one was responsible for the decrease in the carbohydrate content observed with storage time. The fraction was presumably of low molecular mass. Humic compounds and volatile fatty acids (acetate and propionate) were released to the bulk water from the flocs during the storage. A possible mechanism to explain the reduced dewaterability developed during anaerobic storage, partly because of the observed changes in EPS, is discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 44 (1996), S. 823-830 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Changes in the chemical composition of organic compounds in total activated sludge, activated sludge extracellular polymeric substances (EPS), and sludge bulk water during anaerobic storage (12 days) were studied. The background for the study was that anaerobic storage of activated sludge, which often takes place at wastewater treatment plants before dewatering, causes a deterioration of the dewaterability. The reasons are not known at present, but may be related to changes in exopolymer composition of the flocs. The results showed that a fast decrease in total sludge protein and carbohydrate took place within 3 days of anaerobic storage as a result of degradation processes, which accounted for approximately 20% of the organic fraction. The amount of uronic acids and humic compounds remained almost constant in the sludge. The EPS were extracted from the floc matrix using a cationexchange resin. In the EPS matrix a similar initial (2–3 days) degradation of proteins and carbohydrate took place, whereas the content of DNA and uronic acids showed minor changes. The extractability of humic compounds increased during the first 3 days of storage. No changes in extractability of the carbohydrate were observed. A fraction of the EPS protein was found to be difficult to extract but was observed to be degraded during the anaerobic storage. The EPS composition was further characterized by high-performance size-exclusion chromatography analysis obtained by on-line UV detection and post-column detection of proteins, carbohydrates, humic compounds and DNA. Four fractions of polysaccharides were found, of which only one was responsible for the decrease in the carbohydrate content observed with storage time. The fraction was presumably of low molecular mass. Humic compounds and volatile fatty acids (acetate and propionate) were released to the bulk water from the flocs during the storage. A possible mechanism to explain the reduced dewaterability developed during anaerobic storage, partly because of the observed changes in EPS, is discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 755-761 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 755-761 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 7 (1995), S. 589-594 
    ISSN: 1573-5176
    Keywords: PSP Toxins ; HPLC analysis ; Alexandrium spp. ; toxic dinoflagellates ; extraction method ; phycotoxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The optimal conditions were established for extraction of paralytic shellfish toxins from a Danish clone of Alexandrium tamarense using extraction with acetic acid and HCl in the concentration range 0.01–1.0 N. Physical destruction of the cells was investigated microscopically to select the most efficient extraction procedure. The toxin content was quantitated by an automized isocratic reversed-phase high-performance liquid chromatography (HPLC) method. The best results as judged from the total amount of toxins and the toxin profile were obtained using 0.05–1.0 N acetic acid and 0.01–0.02 N HCl. Hydrochloric acid in the concentration range 0.03–1.0 N caused the amount of C1 and C2 toxins to decrease sharply and concomitant increase of gonyautoxins 2 and 3. The phytoplankton extracts with 0.1 to 0.5 N acetic acid or 0.01 N HCl were stable during 6 months at −20 °C, but the extracts with HCl 0.02 N underwent a change in toxin profile, although the total amount of toxins was constant.
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  • 7
    ISSN: 1573-5176
    Keywords: Rhodophyta ; Gigartinales ; Hypnea musciformis ; isethonic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isethionic acid (2-hydroxyethanesulfonic acid) was isolated as salts from a methanolic extract ofHypnea musciformis collected in the Indian Ocean and identified by comparison (nuclear magnetic resonance, infrared and mass spectrometry) with an authentic sample. The compound has not previously been reported from plants. Investigations of 13 other species of red algae showed that only some samples of species of the families Gigartinaceae, Hypnaceae and Solieriaceae (all of order Gigartinales) contained isethionates.
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  • 8
    Publication Date: 2007-11-24
    Print ISSN: 1420-682X
    Electronic ISSN: 1420-9071
    Topics: Biology , Medicine
    Published by Springer
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  • 9
    Publication Date: 1996-02-20
    Print ISSN: 0175-7598
    Electronic ISSN: 1432-0614
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Springer
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  • 10
    Publication Date: 1995-08-01
    Print ISSN: 0175-7598
    Electronic ISSN: 1432-0614
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Springer
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