|Alternative Title||Theoritical and experimental study of floc structure, strength and its controlling
|Place of Conferral||北京
水处理工艺 Floc Structure
Water Treatment Processes.
|Other Abstract||Coagulation and flocculation play a significant role in the drinking water and wastewater treatment. Floc structure and strength, a classical but challenged issue in the study of flocculation, directly affect the removal efficiency of colloid particles. A better understanding of the structure and strength of flocs will be of significant important in improving the efficiency of water treatment processes.
Based on the statistical mechanics, a new dynamic framework was employed to analyze the coagulation processes. The fractal dimension of floc structure was physically derived out, and the relationship between fractal dimensions and some controlling factors was discussed. In order to check the available of theoretical framework, theoretical calculation was provided and comparison between theoretical analyses and the experimental results were conducted.
In order to study the floc structure, the structure, strength and size distribution of flocs, alum-kaolin flocs formed under different mechanisms were investigated at various hydraulic conditions. Furthermore, a new method based on the fractal theory was employed to analyze the strength of flocs. The relationship between fractal dimensions and floc size distribution was then discussed with controlled experiments, providing comparison between calculation results of the new method and the strength factor. The results show that both floc size and fractal dimension of flocs decrease as the increasing of the shear rate and the floc strength follows the hierarchy: gradually increased shear rate from 40 rpm to 60 rpm > stable 60 rpm shear rate > gradually decreased shear rate from 60 rpm to 40 rpm> stable 40 rpm shear rate.
Moreover, SiO2-Alum flocs formed under charge-neutralization and sweeping flocculation were investigated at various hydraulic conditions. The relationship between particle morphology and floc structure and strength was discussed based on the controlled experiments. The result shows that the spherical particles are easier to establish the more compact flocs than amorphous particles. Finally, the relationship between the diversity of flocculants and the structure of flocs was discussed based on some experiments.
In sum, this paper tried not only to give a reasonable description of the floc structure but also to reveal the dynamic mechanisms|
武若冰. 絮体结构、强度与性状调控的理论和实验研究[D]. 北京. 中国科学院研究生院,2007.
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