湖泊底泥絮凝沉降试验研究

Experimental studies of flocculaton settling of sediment from three lakes

湖泊底泥的运动过程产生了内源污染,加剧了湖泊生态环境的恶化。研究湖泊底泥在风浪作用下悬浮后再沉降的运移规律,可为了解湖泊水质变化成因以及开展生态环境治理提供技术支持。本课题采用有机玻璃制作的沉降桶,在静水条件下对太湖、龙感湖、巢湖的底泥进行了沉降试验,研究3个湖泊的水体在不同初始含沙浓度和不同水深条件下含沙浓度的变化,分析了3个湖泊淤泥的沉降规律,近似代表天然湖泊的底泥运动状态。试验研究表明3个湖泊水体中悬浮泥沙的沉降均为絮凝沉降,其沉降过程和沉速与单颗粒泥沙相比均发生了量和质的变化,悬浮泥沙絮凝平均沉速随沉距、含沙浓度的增大而增大。最后得出3个湖泊底泥的沉降速度,其研究结果可为采用絮凝沉降法改善水质环境提供参考依据。

Autogenic pollution sources coming from lake sediment motion process aggravate ecological environment deterioration of lakes. A study of settlement law of lake sediment after suspension by the action of water wave provides a reference for understanding causes of water quality change and ecological environment governance of lakes. Settlement experiments of sediment from the Taihu Lake,Longgan Lake and Caohu Lake under hydrostatic conditions were performed in an organic glass cylinder. The changes in sediment concentrations under the conditions of different initial sediment concentrations and different water depths have been studied,and the laws of the sediment settlement of three lakes have been analyzed,which can approximately represent the dynamic state of the lakes＇ sediment. The analysis results show that the settlement of sediment from three lakes is charactorized by the flocculating settling,and that the settlement process and velocities have quantitative changes and fundamental changes comparing with a single particle sediment. The average flocculating settling velocities increase with the increment of settling height and sediment concentration. The flocculating settling velocities of the sediment from three lakes have been obtained. The experiment results can give a good basis for improving water quality by the flocculation settling method.