河湖淤泥絮凝沉降特性试验研究

絮凝沉降性能是河湖疏浚淤泥资源化处理中重要且未完善的研究课题。以武汉沙湖、官桥湖及南湖3种淤泥为研究对象,通过沉降筒试验,利用清浑交界面沉降速度和上清液浊度研究了粒径分布、初始含沙量及高分子聚合物对河湖淤泥絮凝沉降特性的影响规律,并探讨了沉降筒尺寸对试验结果的影响。试验结果表明:河湖淤泥粒径越小,淤泥絮凝沉降越慢,上清液浊度越小;随初始含沙量的增加,河湖淤泥整体沉降速度变小,但当初始含沙量增加到一定值后,初始含沙量的影响作用开始变弱;高分子聚合物会促进河湖淤泥絮凝沉降;沉降筒尺寸虽然对试验结果略有影响,但对于分析河湖淤泥絮凝沉降特性无较大影响。研究河湖淤泥絮凝沉降特性对于河湖通航、蓄洪、水质修复、疏浚淤泥的处理均有重要意义。

Experimental Research on Flocculation-Settling Property of Silt in Rivers and Lakes

Flocculation-settling property is an important research subject to be improved in the treatment of river and lake dredging silt. The effects of particle size distribution, initial sediment concentration, and high-molecular polymer on flocculation and settling property of dredging silt were examined through settling experiments with the settling velocity of interface between clear and turbid liquid and turbidity of supernatant as indexes. The dredging silts from the Shahu Lake, Nanhu Lake, and Guanqiao Lake in Wuhan were taken as research object. Besides, the influence of settling column size on experiment result was also investigated. Results reveal that the smaller the particle size is, the slower the silt flocculates and settles, and the clearer the supernatant fluid is. The settling velocity decreases with the increase of initial sediment concentration; but the influence of initial sediment concentration weakens when it reaches a threshold value. High-molecular polymer promotes the flocculation-settling property of dredging silt. In addition, the size of settling column has little impact.