Nitrogen and carbon dynamics beneath on-site wastewater treatment systems in Pitt County, North Carolina.

Published

Journal Article

On-site wastewater treatment systems (OWS) are a potentially significant non-point source of nutrients to groundwater and surface waters, and are extensively used in coastal North Carolina. The goal of this study was to determine the treatment efficiency of four OWS in reducing total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) concentrations before discharge to groundwater and/or adjacent surface water. Piezometers were installed for groundwater sample collection and nutrient analysis at four separate residences that use OWS. Septic tank effluent, groundwater, and surface water samples (from an adjacent stream) were collected four times during 2012 for TDN and DOC analysis and pH, temperature, electrical conductivity, and dissolved oxygen measurements. Treatment efficiencies from the tank to the groundwater beneath the drainfields ranged from 33 to 95% for TDN and 45 to 82% for DOC, although dilution accounted for most of the concentration reductions. There was a significant positive correlation between nitrate concentration and separation distance from trench bottom to water table and a significant negative correlation between DOC concentration and separation distance. The TDN and DOC transport (>15 m) from two OWS with groundwater saturated drainfield trenches was significant.

Full Text

Duke Authors

Cited Authors

  • Del Rosario, KL; Humphrey, CP; Mitra, S; O'Driscoll, MA

Published Date

  • January 2014

Published In

Volume / Issue

  • 69 / 3

Start / End Page

  • 663 - 671

PubMed ID

  • 24552742

Pubmed Central ID

  • 24552742

Electronic International Standard Serial Number (EISSN)

  • 1996-9732

International Standard Serial Number (ISSN)

  • 0273-1223

Digital Object Identifier (DOI)

  • 10.2166/wst.2013.765

Language

  • eng