Experiemtnal Study On The Treatment Of Polluted River Water By Group Technology Of BAF, Coagulation And Sedimentation

The contaminated water from the downstream Yangtse Rive was treated by the combination of biological aerated filters (BAF) and the coagulation-sedimentation processes (CS) in this research work. The experiments were conducted in the jar test and modeling tests. In order to compare the treatment efficiency with the unit group, the singular treatment process of BAF and CS was respeactively used for disposing of the polluted river water under the same operating conditionsThe way to combine the BAF and the coagulation-sedimentation(CS) process was investigated in this research work, and the operation parameters for the combination process were optimized to make the treated water comply with the regulation for the industry water supply.For the case of the BAF process alone to treat the polluted water, more than 90% of NH₃-N was removed with the effluent NH₃-N concentration of 0.15 mg/L～0.96mg/L (the reaction condition: burden loading: 4.5m³/m²ç¨£^-1; temperature: 7℃～28℃; initial concentration of COD_Mn: 5.87 mg/L～ 12.36mg/L; concentration of NH₃-N: 4.27 mg/L～8.5mg/L; turbidity: 19.6NTU～53NTU). And the operation loading of NH₃-N was 0.32kg/m³ç¨£^-1 ～ 0.16 kg/m³ç¨£^-1. However, in the BAF process, the removal efficiency of COD_mn was only about 10 ～ 20%, the removal efficiency of turbidity was about 60% and the removal efficiency of NH₃-N remained to be 90～ 100%, Little effect of back washing of the BAF on the removal of NH₃-N was found. But the COD_Mn and the turbidity in the effluent both exceeded the regulated level for the industry water supply.Using the coagulation and sedimentation to treat the polluted raw water under the same reaction condition with the BAF process, it was found that the removal efficiency of turbidity was more than 90% with the effluent turbidity less than 2 NTU when the dosing of coagulants was 40 mg/L, The COD_Mn in the effluent of sedimentation was 4～ 7 mg/L, and the removal efficiency of COD_Mn was about 43—56%. It was observed that the COD_Mn and NH₃-N did not comply with the regulatory requirement for the industry...