Fast start-up and enhancement of partial nitritation and anammox process for treating synthetic wastewater in a sequencing bath biofilm reactor: Strategy and function of nitric oxide

In this study, the partial nitritation and anammox (PN-A) process was initiated within 30 days in a sequencing batch biofilm reactor (SBBR) by employing pre non-aeration and post non-aeration with fixed aeration rates. The average ammonia removal efficiency (ARE), total nitrogen removal efficiency (TNRE) of 98.5 +/- 1.5% and 89.5 +/- 1.6% were achieved. By doubling aeration rate and agitation rate and adopting pre non-aeration, the TNRR was promoted from 0.135 +/- 0.013 kg N center dot m- 3 center dot d-1 to 0.285 +/- 0.015 kg N center dot m- 3 center dot d-1, obtaining an average ARE and TNRE of 97.5 +/- 1.5% and 85.5 +/- 2.6%. Nitric oxide might induce anaerobic ammonia oxidation bacteria (AnAOB) during the start-up stage, and could be an indicator for synergetic state between ammonia oxidation bacteria (AOB) and AnAOB. Lower nitrous oxide emission factor of 0.51% was obtained. The abundance of AOB, AnAOB and nitrite oxidation bacteria (NOB) accounted for 1.6%, 19.3% and 0.3%, respectively.

Automated summary

The study achieved high efficiency in ammonia and total nitrogen removal through optimizing aeration rates and employing specific start-up methods. It was also found that nitric oxide may induce the production of anaerobic ammonia oxidation bacteria, serving as an indicator for the synergistic state between ammonia oxidation bacteria and anaerobic ammonia oxidation bacteria.