Confirming the answer proceeded by Marta L, with considering to the concentration of DO , not less than 7 mg/l, and in stagnant or semi closed water body, authors suggest the concentration of P and N < 0.05 mg/l and 10 mg/l , respectively
Dear All it is unfortunately slightly more complicated. I.e. the regulation talks about sensible and non sensible areas. In the Non Sensible areas (i.e. the Mediterranean ocean via Sea outfall) Nutrient removal is not required.
The whole regulation can be red in the attached document:
Also the values that Bayan mention like a local low value of 0.05 mg P/l is to be defined by the local Country in dependency of what water quality they themselves has planned and announced to the EU-Commission for a given water body, and values like that is hence not general for the whole EU.