Study on Affecting Factors of Zeolite Biological Aerated Filter (ZBAF) in Micro-polluted Raw Water Treatment

The removal of COD_Mn, NH₄⁺-N from micro-polluted raw water were investigated by zeolite biological aerated filter process. Several selected test factors such as media height of BAF, hydraulic retention time(HRT), the air/water ratio and concentration of NH₄⁺-N in raw water were studied in the article. The test Results showed that the removal rate of pollutants from the micro-polluted raw water would improve with the increase of media height at the hydraulic retention time of 30min and the air/water ratio of 1:1. COD_Mn, UV₂₅₄, turbidity were removed mostly at the foremost height of 440mm, and NH₄⁺-N was removed mostly at the height of 220~440mm. The average removal rates of COD_Mn were 36.81%, 33.17% and 26.29% respectively at the hydraulic retention time of 15min, 30min and 60min respectively, air/water ratio of 1:1. When the hydraulic retention time is 30min, 28.24% of COD_Mn and 90.57% of NH₄⁺-N were removed at the air/water ratio of 0.5:1, and 31.20% of COD_Mn and 93.22% of NH₄⁺-N were removed at the air/water ratio of 1:1. When the air/water ratio was 2:1, the average removal rates of COD_Mn and NH₄⁺-N were hardly improved. The appropriate hydraulic retention time and air/water ratio of ZBAF to treat micro-polluted raw Water were 30min and 1:1 respectively.