The total nitrogen in urban sewage treatment can be calculated as 25. I will give you a water quality table with CODcr ≤ 500 mg/L.

BOD5 ≤ 200mg/L.

SS ≤ 200mg/L.

Total phosphorus ≤ 3mg/L.

Ammonia nitrogen ≤ 30mg/L.

Total nitrogen ≤ 40mg/L.

Design effluent quality:

Codcr ≤ 50mg/l

BOD5 ≤ 10/0mg/L.

SS ≤ 10/0mg/l

Total phosphorus ≤ 0.5mg/L.

NH3-N ≤ 5 mg/l (8mg/L when the water temperature is ≤ 12 in winter)

Total nitrogen ≤15mg/l