| Summary: | 博士 === 臺灣大學 === 化學工程學研究所 === 98 === Aerobic granules are compact, strong microbial aggregates that have excellent settling ability and capability to efficiently treat high-strength and toxic wastewaters. The aerobic granules cultivated with low ammonium and phosphates lost structural stability within 3 days in continuous-flow reactors. Conversely, stable aerobic granules were cultivated in substrate with high levels of ammonium salts that could stably exist for 210 days in continuous-flow membrane bioreactors. The scanning electron microscopy, energy dispersive spectroscopy microanalysis and the confocal laser scanning microscopy imaging detected large amounts of calcium and iron precipitates in granule interiors. The Visual MINTEQ version 2.61 calculation showed that the phosphates and hydroxides were the main species in the precipitate.
Internal biofilm was observed in the long-term operating AGMBR system. This study isolated strains in aerobic granule, the surface fouling layer, and biofilm inside hollow-fiber membranes of an aerobic granule membrane bioreactor; analyzed their distributions, sizes, surface charges, and growth behaviors; and determined the quantities of extracellular polymeric substances (EPS) secreted by these strains under different organic loadings. Three strains, which may penetrate the microfiltration membranes, were close relatives of the Ralstonia mannitolilytica strain SDV, Arthrobacter sp. BJQ-2, and Actinobacterium DS3. Among these three strains, only Arthrobacter sp. developed an internal biofilm. The relatively short length of Arthrobacter sp. minimizes resistance to cells moving through the membrane matrix, thereby enhancing its ability to build a biofilm in the interior surface of membranes.
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