三种常见混凝机理为主导条件下絮体特性研究

以模拟低浊微污染水为原水,硫酸铝Al2 (SO4)3]为混凝剂,考察了3种常见混凝机理(电性中和、吸附架桥和网捕卷扫)为主导条件下絮体的成长过程、二维边界分形维数(Dpf)和比表面积及其与混凝效果的相关性.结果表明:吸附架桥为主导机理下絮体最大增长速率S (0.951)最快,达到稳定后絮凝指数FI最大(3.7%),二维边界分形维数Dpf最大(1.587),絮体呈块状且絮体间出现孔状间隙,比表面积介于网捕卷扫和电性中和之间网捕卷扫(83.646m2/g)>吸附架桥(98.808m2/g)>电性中和(116.046m2/g)];FI值、S及Dpf变化与浊度去除率相关性较好,其相关系数分别达0.979、0.982和0.963,同时比表面积大的絮体吸附容量大,有机物的去除率高.

Study on flocs characteristics under three common dominant coagulation mechanisms

Simulated low turbidity and micro-polluted water was used as raw water and aluminium sulfate was used as coagulant,the flocs growth process, two-dimensional perimeter fractal dimension (Dpf), specific surface and the relationship between flocs characteristics and coagulation efficiency under three common coagulation mechanisms (charge neutralization, bridging and sweep flocculation) were investigated. The results indicated that the highest growth rate S (0.951), stable flocculation index (FI) value (3.7%) and two-dimensional perimeter fractal dimension (1.588) of flocs were formed under bridging dominated the coagulation mechanism. Additionally, the flocs stick together in clumps with porous space in such condition and its specific surface was between that formed by sweep flocculation and charge neutralization as the following hierarchy: sweep flocculation (83.646m2/g)>bridging (98.808m2/g) >charge neutralization (116.046m2/g). The FI value, S and Dpf had a significant linear correlation with the turbidity removal efficiency, the correlation coefficient reaching up to 0.979、0.982 and 0.963, respectively. The flocs with higher specific surface and bigger adsorption capacity may be contributed to a higher organic matter removal.