Microbial community profile of a biological excess phosphorus emoval (BEPR) activated sludge system using a cultivation-independent approach

Abstract

It is generally accepted that biological release of phosphorus in the anaerobic zone of a nutrient removal system and phosphorus accumulation in the subsequent aerobic zone is directly proportional to the quantity of volatile fatty acid or the readily biodegradable COD fraction (fbs) entering the system. This will enrich for polyphosphate accumulating organisms (PAOs) in the system and an increase in biological phosphorus removal will be observed. Enrichment for PAOs during the present study was essentially achieved by increasing both the phosphorus and f bs concentrations (maintaining constant total COD loads) in the influent to the system. Fluorescence in situ hybridisation (FISH) using kingdom-, subdivision-and genus-level probes was used to identify and enumerate the bacterial community implicated in biological excess phosphorus removal (BEPR). Hybridisation of up to 78% of the cells (in relation to DAPI staining) with probe EUB338 indicated that a high proportion of the sludge comprised metabolically active bacteria.

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