$1.$ How much $($in kg$/$day$)$ can a wastewater treatment plant of $5000$ m$3/$day discharge to a river with a drought flow of $137\mathrm{.}7$ m$3/$min if the BOD$5$ in the river after initial dilution must not exceed $1$ mg$/$L$?$ What degree of treatment $(\%$ satisfied$)$ does this represent, assuming the plant receives an influent wastewater of $250$ mg$/$L BOD$2.2.$ For the Problem $1$ above, the dissolved oxygen concentration $($DO$)$ and temperature $($T$)$ of the treated wastewater and the river are listed below:Treated wastewater: DOw $=2$ mg$/$L; T $=20$ CRiver upstream: DOr $=9$ mg$/$L; T $=15$ CDetermine the DOm, Tm$,$ and initial oxygen deficit $($Do$)$ after the complete mixing of the treated wastewater and the river. It is assumed that air pressure is $1$ atm and it contains $20\%$ oxygen and the saturated dissolved oxygen concentration $($DOs$)$ equals $9\mathrm{.}75$ mg$/$L$.$