|Ph.D Student||Belinsky Michael|
|Subject||Theoretical and Experimental Characterization of Suspended|
Particulate and Hydrophobic Pollutant Distribution
in Lakes and Reservoirs
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Hillel Rubin|
|Full Thesis text - in Hebrew|
This study incorporated performing experiments aiming to characterize the behavior of hydrophobic pollutants and Suspended Solid Particles (SSP - particulate) in water columns of lakes and reservoirs. Experiments were performed with a small scale water column and high-tech measuring facilities. The research clarifies the influence of the turbulence on the fate of hydrophobic pollutants reaching large water bodies, and its effect on the rate of hydrophobic pollutant absorption onto the SSP from the water phase. Absorption processes influenced by the turbulence due to two main reasons: dependence of the turbulence intensity on resuspension of the SSP and the effect of turbulence on the diffusion in the layer surrounding the particle.
Particular attention was dedicated to the flow field taking place at the bottom of the water column. The experiments showed that a critical shear stress leads to SSP resuspension at the water column's bottom. The critical shear stress causing resuspension is represented by the turbulent kinetic energy created by the oscillating grids. The experimental results indicated that a factor of constant value expresses the ratio of the critical shear stresses in open channel to its value in the water column of the lake.
For predicting the fate of hydrophobic pollutants reaching lakes, an experimental model composed of an absorbing agent and an absorbed material was selected. The study indicated that turbulence increases the absorption rate in tens of percents. This result may be useful in planning sewage water purification facilities and enable constructing smaller facilities or increase water discharges passing through purification facilities
The research work incorporated some sailings missions in Lake Kinneret, during which, we investigated the influence of the inner lakes flow on the water turbidity. Field experiments were conducted when the lake was stratified, and the presence of thermocline did not allow rising of SSP towards the water surface. The analysis indicated the main cause for SSP resuspension in this case was internal waves. However, the lake stratification did not prevent the SSP spreading from the lakeshore towards its canter. The increased water turbidity was observed at a distance of a few kilometres from the shore of Lake Kinneret.
The results of this study may lead to better understanding of various phenomena and provide some links between the parameters affecting directly and indirectly the water quality in lakes and reservoirs.