Nitrogen transformations during soil-aquifer treatment of wastewater effluent - Oxygen effects in field studies

Jennifer H. Miller, Wendell P. Ela, Kevin E. Lansey, Peter L. Chipello, Robert G. Arnold

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Depth-dependent oxygen concentrations and aqueous-phase total ammonia and nitrate/nitrite ion concentrations were measured in the field during the infiltration of wastewater effluent. Measurements illustrated the dependence of nitrogen fate and transport on oxygen availability. Infiltration basins were operated by alternating wet (infiltration) and dry periods. During infiltration periods, ammonia was removed within the top few feet of sediments via adsorption. Biochemical activity rapidly eliminated residual molecular oxygen in the infiltrate, making the soil profile anoxic. During dry periods, oxygen reentered the basin profile and sorbed ammonia was converted to nitrate via nitrification. Oxygen penetrated to a depth of about 0.6 m (2 ft) within the first few days of dry periods. At greater depths, oxygen levels increased more slowly due to a combination of slow transport kinetics and biochemical (nitrogenous) oxygen demand. During normal wet/dry basin cycles consisting of about 4 wet and 4 dry days, the local vadose zone remained anoxic at depths greater than about 1.5 m (5 ft) below land surface. As a consequence, conditions for denitrification were satisfied in the deeper sediments. That is, the nitrate nitrogen produced in near surface sediments moved freely downward with infiltrating water where it encountered an extensive anoxic zone before reaching local monitoring or extraction wells. The relative importance of dissolved organics and sorbed ammonia as electron donors for denitrification reactions remains to be established.

Original languageEnglish (US)
Pages (from-to)1298-1306
Number of pages9
JournalJournal of Environmental Engineering
Volume132
Issue number10
DOIs
StatePublished - Oct 1 2006

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Keywords

  • Denitrification
  • Ground-water recharge
  • Nitrification
  • Oxidation
  • Oxygen
  • Wastewater management

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Environmental Chemistry
  • Environmental Science(all)

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