Northern Ireland Water (NIW) has been operating wastewater treatment plants to achieve the UWWTD population based standards of 15mg/l and 10mg/l TN for many years. Operating to these standards hasn’t achieved ‘good’ status in many of the waters on the coast and this has led to lower TN limits down to 8mg/l TN have being applied to a number of wastewater treatment works. Traditional solutions related to achieving TN limits of 8mg/l would normally involve the introduction of methanol dosing to new assets such as 4 stage Bardenpho or denitrifying sandfilter processes. With limited capital investment available, NIW have had to think ‘outside the box’ and through data gathering and understanding of how to operate assets at their optimum; lower opex focused solutions have been developed. Case studies of 3 sites will be presented to demonstrate how performance can be optimised to achieve TN limits down to 8mg/l whilst saving OPEX costs.