水流紊动特性对活性污泥沉降性能的影响

为优化活性污泥处理系统的设计和运行,在SBR反应器中通过改变搅拌浆的转速,调整水流的紊动条件,借助粒子图像测速技术分析了反应器内水流的紊动特性,研究了反应器内不同区域紊动强度对活性污泥沉降性能的影响.结果表明,搅拌浆叶周围15mm的范围内,紊动强度远高于距桨叶更远的区域,距离浆板5mm的1-1断面和距离浆板60mm的3-3断面搅拌轴心处的紊动强度值分别反映了反应器搅拌主体区和其他区的紊动特征.随搅拌浆转速的增加,反应器内各区域的紊动强度逐渐增加,活性污泥的沉降性能表现出先改善后恶化的规律.当反应器搅拌主体区紊动强度1.51%,其他区紊动强度0.31%时,本试验条件下形成的活性污泥沉降指数(SVI)达到最小值67mL/g,界面沉降速率(ZSV)达到最大值0.20mm/s,活性污泥的沉降性能最佳.搅拌主体区范围较小,紊动强度较高,增强该区的紊动强度会加剧污泥的侵蚀破坏;其他区范围较大,紊动强度较低,增强该区的紊动强度对改善污泥的沉降效果作用明显.工程中可通过降低搅拌主体区的紊动强度,选择其他区适当的紊动强度,改善活性污泥的沉降性能.

Influence of Hydrodynamic Turbulence Characteristics on the Sedimentation of Activated Sludge

For the optimization on design and function of active sludge system, the influences of hydrodynamic turbulence characteristics on the sedimentation of active sludge were studied. Hydrodynamic turbulence conditions were changed by adjustment of stirring paddle in sequencing batch reactor (SBR). With the technology of particle image velocimetry (PIV), the distribution of turbulence intensity under different parts in sequencing batch reactor (SBR) was analyzed. The results show that the turbulence intensity in area within the 15 mm distance around stirring paddle was higher than other areas. The characteristics of turbulence were reflected by the turbulence intensity of string axis in 1-1 section and 2-2 section. With increasing of rotate speed of stirring paddle, the turbulence intensity of different parts in SBR increased gradually, and the sedimentation performances of active sludge improved first and then deteriorated. The best sedimentation performance of active sludge in the experiment, which the smallest sedimentation volume index(SVI) was 67 mL/g,and the largest sedimentation velocity was 0.20 mm/s, occurred when the turbulence intensity of the main part in stirring zone was 1.51% and other part 0.31%. The area of main part in stirring zone was smaller than other parts, and the turbulence intensity of main part in stirring zone was higher than other parts. The hydrodynamic turbulence characteristics of main part had remarkable function on the breaking up of active sludge, while the hydrodynamic turbulence characteristics of other part had higher influence on sedimentation performances of active sludge. Decreasing the hydrodynamic turbulence intensity of main part in stirring zone and increasing the hydrodynamic turbulence intensity of main part in stirring zone can be performed to improve the sedimentation of activated sludge in practice.