Continuing the preparation of the proposal for the Eau Gaullie treatment plant (Problem...

Continuing the preparation of the proposal for the Eau Gaullie treatment plant (Problem 3-14), design the flocculation tank by providing the following for the first two compartments only:

1. Water power input in kW

2. Tank dimensions in m

3. Diameter of the impeller in m

4. Rotational speed of impeller in rpm

Use the following assumptions:

1. Number of tanks = 2

2. Tapered G in three compartments: 90, 60, and 30 s ^–1

3. Gt = 120,000

4. Compartment length = width = depth

5. Impeller type: axial-flow impeller, three blades, N_p = 0.31

6. Available impeller diameters: 1.0, 1.5, and 2.0 m

7. Assume B = (1/3) H

Problem 3-14

The town of Eau Gaullie has requested proposals for a new coagulation water treatment plant. The design flow for the plant is 0.1065 m³/s. The average annual water temperature is 19^oC. The following design assumptions for a rapid-mix tank have been made:

1. Number of tanks = 1 (with 1 backup spare)

2. Tank configuration: circular with liquid depth = 2 × diameter

3. Detention time = 10 s

4. Velocity gradient = 800 s ^{– 1}

5. Impeller type: turbine, 6 flat blades, N _p = 5.7

6. Available impeller diameters: 0.45, 0.60, and 1.2 m

7. Assume B = (1/3) H

Design the rapid-mix system by providing the following:

1. Water power input in kW

2. Tank dimensions in m

3. Diameter of the impeller in m

4. Rotational speed of impeller in rpm