Phosphorus accumulation by bacteria isolated from a continuous-flow two-sludge system

In this articlepolyphosphate-accumulating organisms (PAOs) from a lab-scale continuous-flow two-sludge system was isolated and identifiedthe different phosphorus accumulation characteristics of the isolates under anoxic and aerobic conditions were investigated. Two kinds of PAOs were both found in the anoxic zones of the two-sludge systemone of them utilized only oxygen as electron acceptorand the other one utilized either nitrate or oxygen as electron acceptor. Of the total eight isolatesfive isolates were capable of utilizing both nitrate and oxygen as electron acceptors to uptake phosphorus to some extent. And three of the five isolates showed good phosphorus accumulative capacities both under anoxic or aerobic conditionstwo identified as Alcaligenes and one identified as Pseudomonas. Streptococcus was observed weak anoxic phosphorus accumulation because of its weak denitrification capacitybut it showed good phosphorus accumulation capacity under aerobic conditions. One isolates identified as Enterobacteriaceae was proved to be a special species of PAOswhich could only uptake small amounts of phosphorus under anoxic conditionsalthough its denitrification capacity and aerobic phosphorus accumulation capacity were excellent.