泥沙颗粒生长生物膜后沉降的实验研究Ⅱ：沉降速度计算

Experimental study on the biofilm effects on sediment settling Ⅱ. Settling velocity calculation

泥沙生长生物膜后相应的物理特性会发生改变。本文主要探讨泥沙颗粒在微生物生命活动的影响下沉降特性的改变情况。将官厅水库的泥沙分为6组,使用天然水和营养液的混合液对泥沙进行培养,用来模拟富营养水体中泥沙颗粒特性的发展变化情况。对于生长生物膜后的絮体颗粒在各个不同培养时间的沉降运动,实验采用先进的图像采集观测系统进行拍摄采样,并利用图像分析测量颗粒大小和沉速的变化,推导了生长生物膜后的颗粒沉速计算公式。研究表明生物膜极大地改变了颗粒的表面特性,使得颗粒下沉阻力增大,与同等大小无生物膜黏连的泥沙颗粒相比沉速明显减小。

Freshwater systems, such as rivers, lakes, and reservoirs, are increasingly subjected to environmental stress due to pollution, and the sediment characteristics are greatly affected by the biofilm growth on the particle surface in the contaminated aquatic environments. Results are presented from laboratory ex- periments investigating the influences of biofilm colonization on the particle settling velocity. Sediment parti- cles, sampled from the Guanting Reservoir, were cultivated in a mixture of natural water and nutrition. Par- ticle tracking techniques were employed to record and analyze the particle sizes and settling movement. Experimental data show that the drag force exerted on a bio-particle is larger than that for a primary particle, and a fitting formula for the drag coefficient is proposed.