Total Nitrogen Concentrations in Wastewater Treatment Plant Effluent in the Great Bay Estuary Watershed in 2008

Philip Trowbridge, New Hampshire Estuaries Project

Abstract

Nitrogen enrichment is a growing concern for the Great Bay Estuary. For the 2006 State of the Estuaries report (NHEP, 2006), the NHEP calculated the nitrogen load from wastewater treatment facilities (WWTF) using data on total dissolved nitrogen in WWTF effluent in 2002 from Bolster et al. (2003). The NHEP needs to update this indicator for the 2009 State of the Estuaries report. Not only is more recent data needed but also measurements of total nitrogen are needed to avoid assumptions about the ratio of dissolved to total nitrogen. Therefore, the NHEP allocated staff time to collect effluent samples from the major WWTFs in the Great Bay watershed and funded laboratory analysis of the samples for total nitrogen (TN) and total dissolved nitrogen (TDN).