Question

In water treatment plants, settling basins are used to remove suspended contaminants. Consider asettling basin that is 6.0 ft deep, 6.0 ft wide, and 32 ft long (in the direction of flow). Part A If the water flows at 1.2 ft/s, how long will it take the water pass through the basin? [s] Part B Consider a worst-case scenario where a suspended contaminant enters the basin at the water surface. To be removed, it must settle to the bottom before it is flushed out of the basin. What settling velocity is required to capture this worst-case suspended contaminant? [m/s] Part C Assuming the suspended contaminant has a density of p = 1,200 kg/m³, how big must the contaminant be in order to settle in time? Report your result as a diameter [mm]. Assume water density pr = 1000 kg/m³ and dynamic viscosity µ =0.001518 Ns/m².

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