[Simultaneous nitrification and denitrification by catching bed biofilm reactor]

Catching bed biofilm reactor combined with traditional biofilm process as a novel treatment was developed. The performance of the reactor for nitrogen removal was investigated. Steady removal effect with 81.7% of average COD removal rate was achieved in various hydraulic retention time (HRT). Even when hydraulic retention time (HRT) was only at 3.90 h with average NH4(+) -N volumetric loading of 0.47 kg/(m3 x d) and TN of 0.59 kg/(m3 x d), 92.7% of average NH4(+) -N removal rate and 67.5% of average TN removal rate were achieved. In the experiment dissolved oxygen (DO) was the most crucial factor for removal rates of TN and pH was a crucial factor for removal rates of NH4(+) -N, TN. The optimal condition was with DO 0.1-2.0 mg/L and pH of 7.0-7.5. Mechanisms of TN removal via simultaneous nitrification and denitrification in the experiment were analyzed.