$2-2.$ Determine the required width of the paddle blade and recommend a motor

power $($in watts$)$ and rotational speed $($in rpm$)$ for the horizontal shaft of a cross$-$flow

paddle flocculator for the first compartment of a three$-$compartment flocculation

basin shown in the following Figures $($Figure $1$a and b$).($Note: there are three paddle

wheels on one shaft.$)$ The Figures information and the following assumptions are to

be used in the design:

Figure $1$a:

Figure $1$b:

Assumptions:

Liquid volume $=257\mathrm{.}2m^3$

Velocity gradient $=40s^{-1}$

Motor efficiency $=80\%$

Paddle velocity $=0\mathrm{.}5\frac{m}{s}$

Water temperature $=15C$

Drag coefficient $=1\mathrm{.}8$