Question

Consider a typical settling tank of 10 m diameter and 10 m height. Inlet pipe is approximately 2 m deep from the top of the tank. Perform following preliminary calculations. a. For a water-sand flowrate of 1500 m 3 /hr with 1000 ppm of sand, calculate sand particle size than can be settled in the tank. (Water: density = 1000 kg/m3 , viscosity = 1 cP; Sand: density = 2500 kg/m3 ) (6-marks) b. Consider settling of different sizes (50, 100, 200, 300 µm), calculate required tank size for settling of each particle size at a constant inlet flow rate of 1500 m3 /hr. (4-marks) c. Now consider settling of 50 µm size particles in the tank with diameter of 10 m and height of 10 m, calculate inlet flow rate required, (2-marks) d. For fine particles ( 50 µm), if tank size required to operate at 1500 m3 /hr is very large, suggest design modification to settle the fine particles. (4-marks)

Answer 1