A Decade of Simultaneous Nitrification and Denitrification Experience in Over 60 Conventional and MBR Applications – Lessons Learned

Across the country serious efforts are underway to protect sensitive waterways and to implement sustainable water management plans. The strategies and related policies include discussions about wastewater reuse and the promulgation of increasingly stringent nutrient limits (nitrogen and phosphorus) for wastewater treatment plants (WWTPs). As stakeholders struggle with the cost and benefit of various options to achieve higher levels of nitrogen removal there is a renewed focus on a concept called simultaneous nitrification and denitrification or SND. The ability to promote and benefit from SND is not new but is gaining traction as a cost effective method for achieving total nitrogen concentrations of less than 3.0 mg/l. However alongside obvious benefits attributed to SND, such as energy savings, there have been concerns such as sludge bulking and process control. In this paper we will present the “lessons learned” from over 60 plants by focusing on several ditch, extended aeration and membrane bioreactor (MBR) WWTPs commissioned during the last decade.