$10\mathrm{.}35$ Perform a mass balance for a water treatment plant with the treatment sequence indicated in Figure $9\mathrm{.}1.$ Ignore screenings removed from the bar rack and traveling screen. Use the following information.

Influent flow $-235ML{d}^{-1},$ influent SS $-5\mathrm{.}0mg{L}^{-1}.$

Assume that the s$.$g$.$ of all chemical and other solids is $1\mathrm{.}00.$

Alum is the coagulant added to achieve a concentration of $22mg{L}^{-1}A{l}_2(S{O}_4{)}_3.$ The concentration of the alum feed is $10\%A{l}_2(S{O}_4{)}_3*14H_{2}O.$ There is sufficient alkalinity in the water to react with the alum and form the precipitate $Al(OH{)}_3,$ which does not hydrate.

The sedimentation basin removes $80\%$ of the SS$.$

The underflow from the sedimentation basin contains SS at $0\mathrm{.}55\%.$

The remainder of the suspended particles are removed in the rapid sand filter.

The filter backwash uses $2\%$ of the product water from the filter. The filter backwash water is returned ahead of the mixing unit. Assume that the backwash flow rate is continuous.

Chlorine is added at $1\mathrm{.}0mg{L}^{-1}$ to the effluent before discharge to the clear well. Fluoride is added as NaF from a dry feeder to achieve a concentration of $1\mathrm{.}0mg{F}^{-}{L}^{-1}$ in the effluent before discharge to the clear well.

The vacuum filter achieves a cake content of $35\%$ solids by weight. The vacuum captures $95\%$ of the influent solids. A polymer is added to the influent sludge at a dose rate of $5$ kg polymer$/$tonne of solids. The concentration of polymer in the polymer feed is $90g{L}^{-1}.$

Determine the flows and SS concentrations before and after each unit. Also determine the mass feed rates of chlorine and sodium fluoride to be added on a daily basis.

Figure $9\mathrm{.}1$ Rapid sand filtration water treatment plant.