Abstract
The hypersensitivity of anammox bacteria toward fluctuating temperature (seasonal) conditions significantly limits its real-world application. Biomass immobilization alleviates the impact of environmental shocks on the anammox process. In this study (291 d), a sequencing batch reactor engaging dishwashing scrubbers as model waste biocarriers and an amalgamation of activated, anaerobic, and anammox sludge (1:1:0.5 ratio) as inoculum (at influent pH 8.0) were deployed for the startup of the anammox process. Intriguingly, the SBR was run at ambient temperature (6–37 °C) at varying nitrogen loading rates (g N m−3 d−1) of 20, 30, 40, 46.4, 58, 60, 81.2, 92.8, and 116. Notably, anammox activation took place at ⁓247 d wherein the reactor performance improved and exhibited stable nitrogen removal (NH4+–N, NO2−–N and total nitrogen removals were 100, 99, and 72.04%, respectively). Additionally, post 279 days of reactor operation (280 – 291 d), the reactor demonstrated an average total nitrogen removal rate (g N m−3 d−1) of 88.2 at a maximum nitrogen loading rate (g N m−3 d−1) of 116. The 16S rRNA gene sequencing results revealed that Anammox bacteria predominated in the reactor, highlighting the fact that the reported increase in the percentage abundance of Candidatus Kuenenia at 266 d was exorbitantly higher (41.69%) than inoculum sludge (0.18%). Nitrospira (23.9%) and Nitrosomonas (4.32%), in addition to anammox, were found in high concentrations, suggesting presence of dissolved oxygen in the system.
Acknowledgement
Verma S., reverently recognize the DST INSPIRE Fellowship [No. IF180264], Government of India, for its critical financial assistance and remarkable support for the conduct of this research work.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
Data will be made available on request.