$(6)($i$)$ A metal coating industry is located adjacent to Mudd Creek that flows at $300\frac{L}{s}.$

The industry uses zinc cyanide $Zn(CN{)}_2$ for plating brass and discharges $100\frac{L}{s}$

of $Z{n}^{2+}$ contaminated process wastewater. Estimate the maximum concentration of

$Z{n}^{2+}$ in the wastewater that can be discharged in order to meet the required

maximum concentration of $0\mathrm{.}010mgZ\frac{n^{2+}}{L}$ in the stream. Assume that the

upstream $Z{n}^{2+}$ concentration is $0m\frac{g}{L}$ and that we have steady state conditions

throughout.