Mechanisms of floc formation in sludge conditioning with polymers
Mechanisms of floc formation in sludge conditioning with polymers
复制标题
DOI：
10.2166/wst.1994.0396
复制
发表时间：
1994-10
影响因子：
2.7
通讯作者：
S. Langer;R. Klute;H. Hahn
中科院分区：
文献类型：
--
作者：
S. Langer;R. Klute;H. Hahn
在稀悬浮液的絮凝中，需要一段时间的缓慢混合以增加絮凝发生所必需的颗粒碰撞的可能性。当污泥混合时，碰撞频率很高，以至于在快速混合后立即形成絮凝体。然而，絮凝污泥的受控混合一段时间确实改善了脱水性。所涉及的机制已被详细研究，本文的主题。结果表明，在快速混合和初始絮凝体形成后，溶液中可能仍有聚合物，这取决于聚合物剂量。长时间的混合导致大的聚集体的破裂和尚未被聚合物覆盖的颗粒/絮凝物表面。随后，过量的聚合物吸附到这些表面上。从污泥流变学的变化可以看出，在约半分钟至一分钟的时间内，整体性质发生显著变化。在初始絮凝体形成之后，悬浮液处于具有强烈相互作用的大量絮凝体的三维网络结构的状态。在混合阶段之后，有更多的离散和更少的相互作用的絮体。特别是来自加压过滤的滤饼的性质则更有利。
In flocculation of dilute suspensions a period of slow mixing is necessary to increase the probability of particle collisions that are necessary for flocculation to occur. When flocculating sludges, the collision frequency is so high that flocs are formed immediately after rapid mixing. However, controlled mixing of the flocculated sludge for some time period does improve dewaterability. The mechanisms that are involved have been studied in detail and the subject of this paper. The results show that after rapid mixing and initial floc formation there might still be polymer in solution, depending on polymer dose. Prolonged mixing results in breakage of large aggregates and in particle/floc surfaces that are not yet covered with polymers. Subsequently the excess polymer adsorbs onto these surfaces. From changes in sludge rheology one can see that within a period of about one half to one minute the bulk properties change dramatically. After the initial floc formation the suspension is in a state characterized by a three-dimensional network structure with strongly interacting, voluminous flocs. After the mixing period there are more discrete and less interacting flocs. Especially the properties of the filter cake from pressure filtration are then more favorable.