Inadvertently enriched cyanobacteria prompted bacterial phosphorus uptake without aeration in a conventional anaerobic/oxic reactor.

The enhanced biological phosphorus removal (EBPR) process requires alternate anaerobic and aerobic conditions, which are regulated respectively by aeration off and on. Recently, in an ordinary EBPR reactor, an abnormal orthophosphate concentration (PO-P) decline in the anaerobic stage (namely non-aerated phosphorus uptake) aroused attention. It was not occasionally but occurred in each cycle and lasted for 101 d and shared about 16.