$(25$ points$)$ You have been asked to evaluate the ability of a horizontal flow gravity grit

chamber to remove particles having a diameter of $1\mathrm{.}31{10}^{-4}m.$ The depth of the grit

chamber is $1\mathrm{.}0$ m $.$ The detention time $(t_o)$ of the liquid in the grit chamber is $60$ s $.$ The particle

density is $1\mathrm{.}83\frac{g}{c}{m}^3.$ The water temperature is $12C.$

Assume the density of water is $1,000k\frac{g}{m^3}.$

The dynamic viscosity of water at $12C$ is $1\mathrm{.}235$mPa$*s$

The kinematic viscosity at $12C$ is $1\mathrm{.}236*({10}^{-6})*\frac{m^2}{s}.$

$($a$)$ Determine the settling velocity of particles $($Vs$)$ and the Reynolds number. Using the

Reynolds number, define the flow pattern among laminar, transition and turbulent.

If you need to use the Newton's equation for particle settling velocity calculation,

$v_s=[\frac{4g({}_s-)d}{3C_{D,}}{]}^{\frac{1}{2}}$

please repeat calculation twice using the Newton's equation and present settling velocity.

$($b$)$ What is $\%$ removal of particles

$(10$ points$)$ You have been asked to evaluate the ability of a grit chamber to remove particles

having a settling velocity of $0\mathrm{.}0008\frac{m}{s}.$ The surface area of the grit chamber is $520m^2.$ The

flow rate $(Q)$ entering to the grit chamber is $8200$ gallons$/$minute$.$

What is the percent removal of particles? gallon