摘要：Operating process at low dissolved oxygen (DO) concentrations is a good way to reduce the energy costs in wastewater treatment. Considering the limited DO concentrations (0.2-0.3 mg/L), it remains unclear whether nitrification will be achieved and which microbial groups are affected during the process. In the study, nitrification was realized in the nitrifying reactor at limited DO concentrations (0.2-0.3 mg/L), and the bacterial community both in the nitrifying sludge and the seeding sludge almost has the same phyla after over two months operation. However, autotrophs of Nitrosomonadales instead of heterotrophs of Burkholderiales and Rhodocy- clales finally became the dominant microbes in nitrifying sludge. Regarding nitrifiers, the respective abundance of nitrite oxidizing bacteria (NOB) of Ni- trospira and ammonium oxidizing bacteria (AOB) of Nitrosomonas were 2.41% and 37.4% in nitrifying sludge. In spite of the low ratio of NOB to AOB, the reactor performed nitratation process rather than ni- tritation process. The study characterized the microbial community shift, evidenced that efficient nitrification can occur at limited DO concentrations (0.2-0.3 mg/L), and demonstrated the relationship between performance and microbial structure in the nitrification reactor.
