絮体分形结构对沉淀速度影响研究  

Effects of Fractal Structure on Settling Velocities of Flocs

作　　者：钟润生[1] 张锡辉[1] 肖峰[2] 李晓岩[2] 

机构地区：[1]清华大学深圳研究生院环境工程与管理研究中心,深圳518055 [2]香港大学土木工程系

出　　处：《环境科学》2009年第8期2353-2357,共5页Environmental Science

基　　金：国家高技术研究发展计划(863)项目(2002AA601120);国家自然科学基金项目(20721140019;U0773002)

摘　　要：利用基于微天平的质量-粒径法和基于改进粒子图像测速技术的自由沉淀法对高岭土、腐殖酸絮体的分形结构进行了研究.结果表明,质量-粒径法得到的铁盐絮体三维分形维数为2.14-2.28,明显大于铝盐絮体的1.75-1.83,铁盐絮体结构更为致密,而铝、铁-腐殖酸絮体比相应的高岭土絮体分形维数要小.絮体分形维数与沉淀速度具有良好的对应关系,分形维数越大,絮体沉淀速度越大.质量粒径法与自由沉淀法求出的絮体分形维数相吻合,分形絮体沉淀速度不再满足Stokes沉淀速度公式.Fractal structures of kaolin and humic flcos by the mass-size method based on the microbalance and free-settling method based on particle image velocimetry technique were investigated. The results showed that kaolin and humic flocs were characterized by fractal structure. The three-dimensional fractal dimensions of Fe flocs with more compact structure ranged from 2.14 to 2.28 are larger than those of alum flocs ranged from 1.75 to 1.83 by the mass-size method. The fractal dimensions of humic flocs are smaller than those of kaolin flocs. The fractal dimension has a close relationship with the settling velocity of flocs. The larger the fractal dimension, the higher the settling velocity. The fractal dimensions by the mass-size method are in good agreement with those by the free-settling method. The measured settling velocities of fractal aggregates do not follow with Stokes＇ law.

关 键 词：絮体结构 沉淀速度 三维分形维数 腐殖酸 粒子图像测速技术 

分 类 号：X131.2[环境科学与工程—环境科学]