Dissolved oxygen concentration (DO) in the natural environments and engineered systems has a great impact on the kinetics and communities of nitrifiers, as well as the global nitrogen cycle and emission of nitrous oxide. This research had investigated the long-term effect of low DO on the nitrification kinetics, nitrifier communities and the emission of nitrous oxide using an engineered nitrifying system. Results indicated that, complete nitrification was accomplished after a long term operation with a DO of 0.16 mg/L. Under long-term low DO conditions, nitrite oxidizing bacteria (NOB) had become a better oxygen competitor than ammonia oxidizing bacteria (AOB) and, as a result, no nitrite accumulated in the engineered system. Real-time PCR assays indicated that the long term low DO enriched both AOB and NOB in system, increasing nitrification capacity and diminishing the adverse effect of low DO on the overall nitrification performance. As a result, high nitrification efficiency was still maintained in the system under long-term low DO conditions. The increase in the population size of nitrifiers was likely resulted from the reduced nitrifier endogenous decay rate by a low DO. Under long-term low DO conditions, Nitrosomonas europaea/eutropha remained as the dominant AOB, whereas the number of Nitrospira-like NOB became much greater than Nitrobacter-like NOB. Under long-term low DO conditions, the emission of nitrous oxide did not increase significantly. Low DO concentration was thought to be a major factor which would enhance nitrous oxide emission.

Long-term low dissolved oxygen concentration enriches and shifts nitrifier communities

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.