Nitrogen eutrophication (nitrogen has to be removed from the Urban Waste Water Treatement plants belonging to agglomeration of more than 10 000 p.e.) Phosphorus eutrophication (phosphorus has to be removed from the Urban Waste Water Treatement plants belonging to agglomeration of more than 10 000 p.e.) Nitrogen drinking water (nitrogen has to be removed from the Urban Waste Water Treatement plants belonging to agglomeration of more than 10 000 p.e.) Areas where further treatment than that prescribed in Article 4 of the UWWTD is necessary to fulfil Council Directives