| Autor: |
Tanaka, Jun-ichi, Syutsubo, Kazuaki, Watanabe, Kazuya, Izumida, Hitoshi, Harayama, Shigeaki |
| Předmět: |
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| Zdroj: |
Environmental Microbiology; Apr2003, Vol. 5 Issue 4, p278-286, 9p |
| Abstrakt: |
Summary Photo-crosslinked polymer beads were introduced into a laboratory activated-sludge unit containing municipal sewage sludge and the effect on nitrifying capacity was examined. The ammonia load started at a nitrogen-loading rate of 0.02 kg m-3 day-1 and was increased stepwise. It was found that the bead-containing unit could almost completely oxidize ammonia (over 95%) up to a nitrogen-loading rate of 0.216 kg m-3 day-1 , whereas the maximum loading rate of the control unit (without polymer beads) was 0.096 kg m-3 day-1 . The nitrifying potential of suspended and bead-associated organisms in the bead-containing unit was measured under different loading conditions. It was found that the bead-associated organisms exhibited high specific activities under high loading conditions and that the contribution of the bead-associated organisms to nitrification was greater than that of the suspended solids under these conditions. The bacterial population dynamics in the suspended solids and bead-associated organisms were analysed by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments and by fluorescence in situ hybridization with group-specific probes. Among the known nitrifying organisms, ammonia-oxidizing β-proteobacteria and Nitrospira -related organisms were detected by these approaches. A comparison of the activity dynamics and population dynamics, however, suggested a possibility that other organisms may also have been involved in the nitrification process under high loading conditions. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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