Two different mixed sludges (aerobic nitrifying sludge and ANAMMOX-denitrification sludge:R1, and anaerobic digestion flocculent sludge and ANAMMOX-denitrification sludge:R2), were used as inocula in two UBF reactors to enrich Anammox bacteria. Both kinds of mixed sludge set up the Anammox process successfully. It took 36 days for R1, while R2 required 53 days. Nitrogen removal rates of R1 and R2 were high during the whole operation. During the stable operation stage, the removal rates of NH4+-N, NO2--N, and TN were about 99.92%, 96.64%, and 81.87% for R1; and 97.54%, 94.91%, and 80.98% for R2. Illumina High-throughput Sequencing revealed Candidatus Kuenenia was in the top six taxa in the two reactors with 3.22% relative abundance in R1 and 2.35% in R2 after the successful start-up. Simulation results indicated that the Modified Stover-Kincannon model and the second-order model were appropriate models. It was deduced that the N-removal potential of R1 was a little greater than that of R2 after comparing the projected maximum substrate removal rate Umax of the two reactors.
Keywords: anaerobic ammonium oxidation(ANAMMOX); kinetics; microbial community; nitrogen removal performance; seed sludge.