Li Zhen-Liang, Zhang Dai-Jun, Lu Pei-Li, Zeng Shan-Wen, Yang Yong-Hao
Department of Environmental Science, Chongqing University, Chongqing 400044, China.
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing 400044, China.
Huan Jing Ke Xue. 2013 Oct;34(10):3975-80.
Floc size distribution (FSD) and fractal dimension are the important parameters for activated sludge. FSD of aerobic activated sludge during flocculation process was measured by a laser particle size analyzer, and the influence of velocity gradient, VSS/ SS, EPS content and Zeta potential on FSD was investigated. The results showed that the floc volume-average size was negatively correlated to velocity gradient (R > 0. 80) , and the order-of-magnitude of the floc volume-average size was equivalent to that of Kolmogorov scale (their differences were dependent on sludge VSS/SS, floc strength and etc). At a fixing velocity gradient, the floc volume-average size was positively correlated to VSS/SS or EPS (R2 >0. 85) , whereas negatively correlated to Zeta potential. Organic matter and EPS played important roles on the flocculation of activated sludge by enhancing the floc strength and improving the flocculation effect. Compared with polysaccharides, proteins in EPS seemed to be more beneficial for the flocculation of activated sludge. Based on microscopy and image analysis, the 2D and 3D fractal dimension of aerobic activated sludge floc was determined to be 1.28-1.72 and 1.70-2.69, respectively. It was found that fractal dimension (2D and 3D)was decreased with increasing VSS/SS (or EPS content). For the same activated sludge, the 3D fractal dimension was decreased with increasing floc size, and the relationship between 3D fractal dimension and floc size could be approximately described by a power function.
絮体尺寸分布（FSD）和分形维数是活性污泥的重要参数。采用激光粒度分析仪测定了絮凝过程中好氧活性污泥的FSD，并研究了速度梯度、VSS/SS、EPS含量和zeta电位对FSD的影响。结果表明，絮体体积平均尺寸与速度梯度呈负相关（R>0.80），絮体体积平均尺寸的数量级与Kolmogorov尺度相当（两者差异取决于污泥VSS/SS、絮体强度等）。在固定速度梯度下，絮体体积平均尺寸与VSS/SS或EPS呈正相关（R2>0.85），而与zeta电位呈负相关。有机物和EPS通过增强絮体强度和改善絮凝效果，在活性污泥絮凝中发挥重要作用。与多糖相比，EPS中的蛋白质似乎对活性污泥的絮凝更有利。基于显微镜和图像分析，好氧活性污泥絮体的二维和三维分形维数分别确定为1.28 - 1.72和1.70 - 2.69。发现分形维数（二维和三维）随VSS/SS（或EPS含量）的增加而降低。对于相同的活性污泥，三维分形维数随絮体尺寸的增加而降低，三维分形维数与絮体尺寸之间的关系可用幂函数近似描述。
