壳聚糖改性黏土作用下湖泛致黑悬浮物的沉降特性研究

Study on deposition of algal bloom-induced black suspended matter using chitosan-modified clay

为了探讨湖泛致黑物质在壳聚糖改性黏土作用下的絮凝沉降以及再悬浮的规律,利用柱状水槽再悬浮发生模拟装置,选取壳聚糖改性黏土(1 g/L硅藻土+0.2 g/L壳聚糖)作为絮凝剂,进行了风浪扰动作用下太湖湖泛的絮凝及再悬浮过程的室内模拟试验。结果表明:当模拟流速产生的切应力超过0.042 N/m^2时,低浊度组中的黏土絮体产生了明显的再悬浮现象;当流速产生的切应力超过0.109 N/m^2时,高浊度组发生再悬浮。对比太湖不同风速所产生的切应力,发现4 m/s以下的太湖风情产生的湖流切应力不会使黏土絮体发生再悬浮。研究旨在为太湖湖泛的应急处置提供参考。

In order to study the regularities of flocculation,settlement,and resuspension of algal bloom-induced black suspended matter in Taihu Lake when using chitosan-modified clay,an indoor experiment was conducted to simulate the flocculation and resuspension processes under the effects of wind and wave disturbances. A cylindrical tank was used in the experiment,and chitosan-modified clay with doses of 0. 2 g / L of chitosan and 1 g / L of diatomite was selected as the flocculant. The experimental results show that,when shear stress exceeded 0. 042 N / m^2,resuspension occurred in the low-turbidity group; when shear stress exceeded 0. 109 N / m^2,resuspension occurred in the high-turbidity group. Comparison of shear stresses induced by different wind velocities shows that a wind speed of below 4 m / s would not cause floc resuspension. This study aims to provide references for disposal of algal blooms in emergencies in Taihu Lake.