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FLOCCULATION OF FINE-GRAINED LAKE SEDIMENTS DUE TO A UNIFORM SHEAR STRESS
Citation:
Tsai, C., S. Iacobellis, AND W. Lick. FLOCCULATION OF FINE-GRAINED LAKE SEDIMENTS DUE TO A UNIFORM SHEAR STRESS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-87/526.
Description:
Experiments were performed to investigate the effects of fluid shear on the flocculation of fine-grained lake sediments in fresh water. In these experiments, a Couette viscometer was used to apply a uniform shear stress to a sediment suspension. he sediments were from the Detroit River inlet of Lake Erie. hey were prepared such that the initial (unflocculated) size distribution contained approximately 90% of its mass in particles less than 10 um in diameter with the average diameter being about 3.5 um. Experiments were performed at shear stresses of 1,2, and 4 dynes/cm2 and sediment concentrations of 50, 100, 400, and 800 mg/L, values which are characteristic of those found in the Great Lakes. ata in the form of floc size distribution as a function of time were obtained. For steady-state conditions, the median diameters of the flocs formed were typically 20 to 100 um depending on shear stress and sediment concentration. uantitative results for the decrease in the steady-state floc size with increasing shear stress and with increasing sediment concentration were obtained. he times required for flocculation to occur under different conditions were also determined and were typically on the order of 1 hour.