IngentaConnect Physical Enrichment of Polyphosphate-Accumulating Organisms in Ac...

Authors: Hung, Chun-Hsiung; Peccia, Jordan; Zilles, Julie L.; Noguera, Daniel R.

Source: Water Environment Research, Volume 74, Number 4, July/August 2002 , pp. 354-361(8)

Publisher: Water Environment Federation

Abstract:

Two methods that physically separate polyphosphate-accumulating organisms (PAO) from other organisms in activated sludge were developed. The first method used 4'6-diamidino-2-phenylindole dihydrochloride (DAPI) to selectively stain PAO. When excited with light at 340 nm, polyphosphate granules in DAPI-stained cells fluoresce yellow while cells without polyphosphate fluoresce blue. This difference in fluorescent response was used to separate PAO from non-PAO using flow cytometry. The second method consisted of a simple gradient centrifugation to physically separate PAO from non-PAO based on their density differences. Both methods produced cell suspensions with an increased PAO concentration. From an average PAO concentration of approximately 14% in a full-scale process, the DAPI-flow cytometry method produced sorted samples with PAO representing more than 70% of the total cells, while the density gradient method produced an approximate 43 to 48% PAO enrichment. The physical enrichment methods described herein should facilitate the identification and study of PAO that are relevant in full-scale enhanced biological phosphorus removal processes.

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Physical Enrichment of Polyphosphate-Accumulating Organisms in Activated Sludge