Problem $1$

Using the following water quality analyses,

a$)$ Assume all alkalinity is $HC{O}_3^{-}$and pKa$=6\mathrm{.}35$ of the following reaction $(*H_{2}C{O}_4^{+}{H}^{+}+HC{O}_3,),$ determine the $C{O}_2$ content

$($hint: $1$ mole of $H2CO3=1$ mole of $CO2$ since

$($:$C{O}_2(oq)+H_{2}O{H}_{2}C{O}_4^{+}\}$

b$)$ determine the lime and soda ash dose, in $m\frac{g}{l}$ as $CaC{O}_3$ to soften the water to a total hardness of $90m\frac{g}{l}$ as $CaC{O}_3.$

$\backslash$table$[[$Thames RIver, London$],[\backslash$table$[[$Constituent$],[$Total hardness$]],$Expressed as Mililgrams per IIte!$],[CaC{O}_3,260\mathrm{.}0],[$Calcium hardness,$CaC{O}_3,235\mathrm{.}0],[$Magnesium hardiness,$CaC{O}_3,25\mathrm{.}0],[$Total iron,$Fe,1\mathrm{.}8],[$Copper$,Cu,0\mathrm{.}05],[$Chromium$,Cr,0\mathrm{.}01],[$Total alkalinity,$CaC{O}_3,130\mathrm{.}0],[$Chloride$,Cl,52\mathrm{.}0],[$Phosphate $($total$),P{O}_4,1\mathrm{.}0],[$Silica$,Si{O}_2,14\mathrm{.}0],[$Suspended solids,,$43\mathrm{.}0],[$Total solids,,$495\mathrm{.}0],[p{H}^a,,7\mathrm{.}4]]$