2. The flocculation process in one treatment train at a surface water treatment plant is to be designed to treat a flow rate of 12 ML/d (million litter/d) with a hydraulic detention of 30 min. The flocculation basin should be divided into 4 equally sized stages with successively lower velocity gradients in each stage (that is, tapered flocculation). The velocity gradients in stages 1, 2, 3 and 4 should be 80, 65, 50 and 35 s-1, respectively. The water temperature is 15C. Calculate the volume of the flocculation basin, the volume of each stage, and the power required for the flocculator in each stage