TPS suggested that if the District were to make changes with the SNDR control parameters, it would be possible to achieve a state where nitrification and denitrification occurred continuously.
Plant staff proposed to TPS the idea of pulling the second two SNDRs out of the cooling loop so the contents of only the Cooling Tank and SNDR 1 Reactor would be exchanged, which would help to preserve the relatively soluble carbon transferred from the ATADs.
From the plant operation staff viewpoint, if any bad chemistry started in the first SNDR reactor, it would be oxidized in the following MTAD aerobic digesters and there would be the potential to scrub some of the off gas that is pulled through the headspace of the reactors, as well.
In 2014, Plant operation staff implemented the change from three SNDR tanks to one SNDR followed by two MTADS along with the TPS recommended control modification.
The changes to the SNDR operation and use of the MTADs have reduced the costs of dewatering as well.