Understanding the role of Tetrasphaera in enhanced biological phosphorus removal

The enrichment of enhanced biological phosphorus removal (EBPR) sludge with Tetrasphaera was obtained for the first time using glutamate as sole carbon source. Two configurations were tested, an SBR with anaerobic/aerobic sequence and a continuous anaerobic/anoxic/aerobic (A/O) pilot plant. Better results and improved stability was obtained in the continuous A/O operation. Accumulibacter were also detected in both systems, as anaerobic conditions allow fermentation of glutamate producing volatile fatty acids, which are its preferred carbon source. This blocks the possibility to obtain a pure culture of Tetrasphaera using only glutamate. Results with SBR cycle studies indicate that the recovery of PHA and glycogen during the anaerobic phase only accounts around 20% of the carbon source consumed, indicating that other storage routes should be studied to identify the fate of the carbon source for Tetrasphaera.