Question $2$:

A settling column analysis was conducted on

wastewater containing TSS particles that

display type$-$II settling and yielded the results

shown in the table below $($entries are

concentrations at stated times, which can be

converted to percent removal by subtracting

the values given from the initial concentration,

at time $0).$

The wastewater is to be treated using a

horizontal settling tank with a depth of $2m$ and

an overflow rate of $2\frac{m}{h}r.$

$2.$a$)$ Determine the removal efficiency $(\%)$ of the

settling tank.

$2.$b$)$ If you needed to achieve $95\%$ removal

using the tank dimensions given, you would

need to change the flowrate. This results in a

change in residence time and overflow rate.

Without doing any calculations $($i$.$e$.,$ just by

looking at the graph$),$ give your best estimate of

an approximate new residence time to achieve

$95\%$ removal. Does this result in an increase or

a decrease to the overflow rate of the clarifier?