2012 Volume 80 Issue 3 Pages 253-260
Nitrogen removal performance was investigated by using observed data in rural sewerage facilities with intermittent aerobic suspended-growth processes. It was found that the effective nitrification-denitrification could be achieved by maintaining aeration time, aeration rate at aeration phase and controlling stir time at stir without aeration phase in cyclic operating conditions. The nitrogen removal reaction was assumed to be governed by first-order function with complete-mix system of biological treatment process. It was recognized that the nitrogen reaction rate was influenced by the temperature and dissolved oxygen (DO) concentration at aeration phase in aeration tank. The nitrogen removal was confirmed to be dependent on mixed-liquor suspended solids (MLSS), hydraulic retention, temperature, and DO concentration at aeration phase in aeration tank. The relationship between nitrogen removal and hydraulic retention time, MLSS cloud be modeled as the form of rectangular hyperbolas. On the base of the influent temperature, the control of MLSS, hydraulic retention, stir time and amount of aeration in aeration tank are important factors in maintaining stable nitrogen removal efficiency.