[Enrichment and dynamic analysis of deammonification granules]

Deammonification process was started-up in a sequencing batch reactor (SBR) seeded with anaerobic granular sludge. A kinetic model describing deammonification process was proposed. Due to the presence of concentration gradient of dissolved oxygen (DO) in granular sludge, model correction factors of DO were introduced. The influences of denitrification process, nitrite and DO on granular sludge activity were studied by model and good agreement was obtained between the experimental results and simulation results. Heterotrophic denitrifiers has some influence on the ANAMMOX process during the initial cultivation, and the influence decreases gradually during the following operation period. When nitrite concentration is 20-30 mg/L, a total nitrogen removal efficiency begins to drop caused by inhibition of nitrite. With high or low DO concentration, the activity of deammonification is inhibited. A total nitrogen removal efficiency can simultaneously reach higher levels by controlling appropriate DO related NH4(+) -N concentration of inflow. In a NH4(+) -N concentration of 80 mg/L, the optimal DO level for a maximal nitrogen gas production is at 0.3-0.6 mg/L.