Nitrification in Premise Plumbing: Role of Phosphate, pH and Pipe Corrosion

Yan Zhang, Allian Griffin and Marc Edwards*
418 Durham Hall, Civil and Environmental Engineering Department Virginia Tech, Blacksburg, Virginia 24061
Environ. Sci. Technol., 2008, 42 (12), pp 4280–4284
DOI: 10.1021/es702483d
Publication Date (Web): April 16, 2008
Copyright © 2008 American Chemical Society
* Corresponding author phone: (540)231-7236 ; fax: (540)231-7916; e-mail: edwardsm@vt.edu.
This article is part of the The Worlds Water special issue.

Abstract

Nitrification in PVC premise plumbing is a weak function of pH over the range 6.5–8.5 and is insensitive to phosphate concentrations 5–1000 ppb. Lead pipe enhanced nitrification relative to PVC, consistent with expectations that nitrifiers could benefit from ammonia recycled from nitrate via lead corrosion. Relatively new copper pipe (<1.5 years old) did not allow nitrifiers to establish, but nitrifiers gradually colonized over a period of months in brass pipes when copper concentrations were reduced by pH adjustment or orthophosphate. Nitrifiers were inhibited by trace copper, but not by lead levels up to 8000 ppb. In some systems using chloramines, brass in plastic plumbing systems might be more susceptible to lead/copper leaching, and accelerated dezincification, due to lower pH values resulting from nitrification.

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History

  • Published In Issue June 15, 2008
  • Article ASAPApril 16, 2008
  • Received: October 1, 2007
    Revised: February 18, 2008
    Accepted: February 20, 2008

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