WATER POLLUTION AND ITS TREATMENT TECHNOLOGIES PROBLEMS $($II$)$

Problem $5.-$ A wastewater treatment plant treats an average daily flow of $91500m^3$ from a residential area. In this plant there is disused channel that could be exploited as a sand removal unit. It has the following dimensions: $9\mathrm{.}10m($length$)1\mathrm{.}50m($width$)2\mathrm{.}10m($height$).$

Particles size distribution is given in the table below. Determinations indicate that these particles' specific relative mass is $2\mathrm{.}65.$

$\backslash$table$[[\%$ mass,$40,2,20,10,5],[$diameter $(mm),2\mathrm{.}0,1\mathrm{.}0,0\mathrm{.}5,0\mathrm{.}3,0\mathrm{.}2]]$

a$)$ This unit is expected to remove at least $80\%$ of the sand. Is this channel adequate to fulfill this requirement?

b$)$ Determine the mass of particles $($in $\%)$ that would be removed in this channel.

Assume that the efficiency of collection is the ratio between the real length and the theoretical length to capture $100\%$ of the particles of a specific diameter.

DATA Viscosity $H_{2}O={9\mathrm{.}9510}^{-4}Pa*S$