关键词: 反渗透预处理, 混凝-沉淀, 气浮, 砂滤, 纤维过滤, 超滤

Abstract: Different seawater pretreatment processes were studied in terms of comparative analysis of turbidity, chemical oxygen demand (COD_Mn), pollution density index (SDI₁₅), etc and the effects on ultrafiltration membrane flux of different pretreatment processes. Coagulation-sedimentation or air flotation process can reduce seawater turbidity effectively. With sand filtration or fibre filtration, turbidity can be reduced to around 0.3NTU. When seawater was treated by the ultrafiltration, regardless of the method, the turbidity of the water and SDI₁₅ can meet the requirement of reverse osmosis. When ultrafiltration is adopted directly, the removal effect of COD_Mn was very bad. When ultrafiltration combines with coagulation-sedimentation or air flotation, the removal rate of COD_Mn was enhanced. Pretreament methods have a great influence on ultrafiltration membrane flux. Ultrafiltration membrane flux declined rapidly by ultrafiltration directly. Membrane flux attenuation slows by coagulation-sedimentation or air flotation. Membrane flux attenuation was well controlled after sand filtration or fibre filtration. Membrane flux attenuation is lowest by using coagulation-sedimentation/ fibre filtration.

Key words: reverse osmosis pretreatment, coagulation-sedimentation, air flotation, sand filtration, fibre filtration, ultrafiltration