Influencing Factors on Nitrogen Removal Performance of Combined Biological Aerated Filter for Secondary Effluent from Municipal WWTP

A pilot-scale study was conducted to investigate the principal influencing factors on nitrogen removal performance of combined biological aerated filter (CBAF), including external carbon source dosage, ratio of air to water and hydraulic loading rate, with inflow of secondary effluent form a municipal WWTP in Shenzhen city. Moreover, the optimal operation mode of CBAF was determined as follows: with 15~25 mg COD_Cr/L of added carbon source, 2:1 of the ratio of air to water and 10 m³/m²-d of hydraulic loading rate, CBAF had an excellent and stable removal performance of nitrogen under this running mode. When the concentrations of NH₄ ⁺-N and TN in the influent were 1.0~17.4 mg/L and 7~23 mg/L, the concentrations in the effluent were lower than 2 mg/L and 15 mg/L respectively. The water quality of the effluent was in accordance with the requirements of Water Quality Standard for Scenic of Environment Use (GB/T18921-2002).