Design a denitrification unit for a separate stage nitrification$/$ denitrification process. The

average wastewater flow is $10$ MLD and it has been determined that the effluent from the

nitrification will contain $55$ mg$/$L nitrate nitrogen, $2$ mg$/$L dissolved oxygen and $3$ mg$/$L nitrite

nitrogen. A $95\%$ nitrogen removal efficiency is desired at a operating temperature of $150$ C

and pH$=7\mathrm{.}0.$ Also, calculate the amount of sludge produced, and the amount of external carbon

required.