Balancing Denitrification and Anammox Activities in Mainstream Deammonification: Influence of COD Input and Aeration Regime

This work describes the influence of the organic carbon to nitrogen ratio and aeration regime on deammonification processes in mainstream wastewater treatment. Two different C/N ratios and two aeration regimes were studied in this research using sequencing batch reactor (SBR) systems. The results of the experiment showed that as COD/N ratio went from 1.7 to 4.8, the percentage of anammox contribution to total nitrogen removal decreased while the total nitrogen removal rate increased. These results showed that although nitrogen removal was limited by NOB out-selection, higher rates could be obtained by increasing COD/N ratio. The higher the ratio is, the lower the anammox contribution that could be achieved. Moreover, in the study of aeration frequency, the results showed that higher aeration frequency resulted in higher AerAOB/NOB ratios under lower C/N conditions. It could be concluded that when C/N ratio in the influent was low, it was easier to achieve better nitrogen removal through anammox, but higher C/N ratio could be helpful for more total nitrogen removal in general. Higher aeration frequency could also be beneficial for anammox process in mainstream.