To remove nitrogen (28 mg/L NH4+ as N) from raw wastewater, a WWTP implement nitrification-denitrification treatment to treat 106 m3/d of sewage.

(a) Write down the nitrification reactions occurring in the nitrification tank, and the overall denitrification reaction (using methanol, CH3OH, as the organic carbon) occurring in the denitrification tank.

(b) How much organic carbon in the form of methanol (mg/L) is needed for the denitrification?

(c) To save energy and lower the cost, the plant is going to run a short-cut nitrification- denitrification. Calculate O2 and methanol required per day to treat the same influent.

(d) If the plant implements partial nitritation and anammox process, how much O2 and methanol would be needed for treating the same influent?