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研究报告

Process development of pressure reinforced coagulation and sedimentation for removing Cyanobacteria in source water

摘要：为了强化蓝藻混凝沉淀去除效果,采用外加压力破坏藻细胞内气囊,使藻类失去浮力,再经混凝沉淀去除.通过静态实验测定了太湖蓝藻水在0~0.7 MPa预压力作用后混凝沉淀效果,并与预氧化混凝沉淀工艺进行了比较.结果表明,在预压力0.4~0.7 MPa作用下取得了较好的效果,沉淀出水浊度为1.04~0.69 NTU;叶绿素a浓度为2.9~0.8 μg·L^-1,去除率为95.8%~98.8%;COD_Mn为3.8~2.9 mg·L^-1,去除率为66.2%~74.1%;UV₂₅₄值为0.0686~0.0646,去除率为23.7%~28.1%.预加压工艺比预氧化工艺节省混凝剂50%.动态实验表明,预压力混凝沉淀过滤出水浊度小于0.25 NTU;叶绿素a浓度小于1μg·L^-1,平均去除率为99.5%;COD_Mn小于3.6 mg·L^-1,平均去除率为70%;UV₂₅₄值小于0.057,平均去除率为33.7%.过滤出水水质优于饮用水水质标准.

Abstract：In order to improve the removal efficiency of cyanobacteria by coagulation and sedimentation process, external pressure was applied on algae cells to destroy the gas vesicle within it. As a result, the algae loses buoyancy, and can be easily removed by coagulation and sedimentation. Static coagulation sedimentation experiment was performed with the pre-pressure of 0~0.7 MPa, and compared with pre-oxidation coagulation sedimentation process. The result is perfect in the pressure range of 0.4~0.7 MPa. The turbidity of water after sedimentation is 1.04~0.69 NTU. The concentration of Chlorophyll-a is 2.9~0.8 μg·L^-1, and the removal rate is 95.8%~98.8%. The concentration of COD_Mn is 3.8~2.9 mg·L^-1, and the removal rate is 66.2%~74.1%. The concentration of UV₂₅₄ is 0.0686~0.0646, and the removal rate is 23.7%~28.1%. Pre-pressured process saves coagulant by 50% compared to pre-oxidation process. The dynamic experiment shows that the turbidity of pre-pressure coagulation and sedimentation filter water is less than 0.25 NTU. The concentration of chlorophyll-a is less than 1 μg·L^-1, and the average removal rate is 99.5%. The concentration of COD_Mn is less than 3.6 mg·L^-1, and the average removal rate is 70%. The concentration of UV₂₅₄ is less than 0.057, and the average removal rate is 33.7%. The filtered water quality is better than the drinking water quality standards.