College of Environmental Science and Engineering, Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing 100083, China.
Water Res. 2011 Jul;45(13):3871-82. doi: 10.1016/j.watres.2011.04.042. Epub 2011 May 4.
The rheological and fractal characteristics of raw (unconditioned) and conditioned water treatment residuals (WTRs) were investigated in this study. Variations in morphology, size, and image fractal dimensions of the flocs/aggregates in these WTR systems with increasing polymer doses were analyzed. The results showed that when the raw WTRs were conditioned with the polymer CZ8688, the optimum polymer dosage was observed at 24 kg/ton dry sludge. The average diameter of irregularly shaped flocs/aggregates in the WTR suspensions increased from 42.54 μm to several hundred micrometers with increasing polymer doses. Furthermore, the aggregates in the conditioned WTR system displayed boundary/surface and mass fractals. At the optimum polymer dosage, the aggregates formed had a volumetric average diameter of about 820.7 μm, with a one-dimensional fractal dimension of 1.01 and a mass fractal dimension of 2.74 on the basis of the image analysis. Rheological tests indicated that the conditioned WTRs at the optimum polymer dosage showed higher levels of shear-thinning behavior than the raw WTRs. Variations in the limiting viscosity (η(∞)) of conditioned WTRs with sludge content could be described by a linear equation, which were different from the often-observed empirical exponential relationship for most municipal sludge. With increasing temperature, the η(∞) of the raw WTRs decreased more rapidly than that of the raw WTRs. Good fitting results for the relationships between lgη(∞)∼T using the Arrhenius equation indicate that the WTRs had a much higher activation energy for viscosity of about 17.86-26.91 J/mol compared with that of anaerobic granular sludge (2.51 J/mol) (Mu and Yu, 2006). In addition, the Bingham plastic model adequately described the rheological behavior of the conditioned WTRs, whereas the rheology of the raw WTRs fit the Herschel-Bulkley model well at only certain sludge contents. Considering the good power-law relationships between the limiting viscosity and sludge content of the conditioned WTRs, their mass fractal dimensions were calculated through the models proposed by Shih et al. (1990), which were 2.48 for these conditioned WTR aggregates. The results demonstrate that conditioned WTRs behave like weak-link flocs/aggregates.
本研究考察了原水（未处理）和处理后水 处理污泥（WTR）的流变性和分形特征。分析了随着聚合物剂量的增加，这些 WTR 系统中絮体/聚集体的形态、大小和图像分形维数的变化。结果表明，当用聚合物 CZ8688 对原 WTR 进行调理时，在 24kg/吨干污泥的最佳聚合物剂量下观察到最佳效果。随着聚合物剂量的增加，WTR 悬浮液中不规则形状的絮体/聚集体的平均直径从 42.54μm 增加到数百微米。此外，调理后的 WTR 系统中的聚集体显示出边界/表面和质量分形。在最佳聚合物剂量下，形成的聚集体具有约 820.7μm 的体积平均直径，基于图像分析，具有一维分形维数 1.01 和质量分形维数 2.74。流变学测试表明，在最佳聚合物剂量下调理后的 WTR 表现出比原 WTR 更高的剪切稀化行为。调理后的 WTR 随污泥含量变化的极限粘度（η(∞)）可以用线性方程来描述，这与大多数城市污泥常见的经验指数关系不同。随着温度的升高，原 WTR 的 η(∞)比原 WTR 的 η(∞)下降得更快。用阿伦尼乌斯方程对 lgη(∞)∼T 之间的关系进行良好拟合，表明 WTR 的粘度活化能比厌氧颗粒污泥（2.51 J/mol）（Mu 和 Yu，2006）高得多，约为 17.86-26.91 J/mol。此外，宾汉塑性模型充分描述了调理后的 WTR 的流变性，而原 WTR 的流变性仅在某些污泥含量下符合赫谢尔-布尔克利模型。考虑到调理后的 WTR 的极限粘度与污泥含量之间的良好幂律关系，通过 Shih 等人提出的模型（1990 年）计算了它们的质量分形维数，这些调理后的 WTR 聚集体的质量分形维数为 2.48。结果表明，调理后的 WTR 表现为弱键合絮体/聚集体。
