ABSTRACT
This chapter assesses whether and how certain operational conditions could enhance the denitrification capacity of polyphosphate accumulating organism I (PAO I). Thus, an enhanced biological phosphorus removal (EBPR) culture enriched with PAO I was operated for a long-term period under anaerobic–anoxic–aerobic conditions. The chapter also assess whether such conditions can stimulate and enhance the use of nitrate by PAO I and elucidate their potential role in EBPR systems performing satisfactory simultaneous denitrification and phosphorus removal. However, that EBPR culture was operated under alternation of anaerobic and microaerophilic conditions. If ultimately denitrifying polyphosphate accumulating organisms (DPAO) are not able to denitrify from nitrate up to relevant and applicable rates, it remains possible that the anoxic P-uptake observed in EBPR systems is carried out partially by side populations. The presence of nitrate during anaerobic conditions has nevertheless been reported in some cases to favour the growth of DPAO in EBPR systems.
