Low temperature soil petroleum hydrocarbon degradation at various oxygen levels

James Walworth, Paul Harvey, Ian Snape

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

A laboratory incubation study was conducted on a petroleum-contaminated soil from Macquarie Island in sub-Antarctic Australia to develop a target O2 level for bioventing. The soil was amended with NH4NO3 (175mg Nkg-1 soil) and 14C-hexadecane (250mgkg-1 soil) and placed in sealed respirometry chambers. The headspaces in the chambers were adjusted to 0, 1, 2.6, 5.2, 10.5, and 20.9% O2. Each chamber was connected to an NaOH CO2 trap and to an O2 feed line (except the 0% O2 chambers were connected to an N2 feed line). Chambers were supplied with O2 in response to pressure drop resulting from CO2 trapping. Soils were incubated at 6°C for 12weeks. O2 consumption and petroleum degradation were maximized in chambers with 10.4% O2. There was a slight decline in both O2 consumption and petroleum degradation at 20.9% O2. As O2 concentrations declined below 10.4% O2 both O2 consumption and petroleum degradation declined markedly. 14C collected in the CO2 traps did not follow this pattern, but was greater in the 1% O2 chambers than in 2.6 or 5.2% O2 chambers. Nitrogen remaining at the conclusion of the study indicated that nitrate was completely consumed in the 0, 1, 2.6, and 5.2% O2 chambers. nC17:pristane and nC18:phytane ratios in the soil at the conclusion of the incubation were significantly lower in the 10.4% O2 chambers than in those with 20.9% O2, and more petroleum hydrocarbons were consumed in the 10.4% chambers. Preferential degradation of pristane and phytane in the presence of limited O2 may be the result of denitrification, evidenced by lower residual nitrate levels in the 10.4 than the 20.9% O2 environment. Ten percent O2 is suggested as a target for O2 enhanced bioremediation.

Original languageEnglish (US)
Pages (from-to)117-121
Number of pages5
JournalCold Regions Science and Technology
Volume96
DOIs
StatePublished - Dec 1 2013

Keywords

  • Aeration
  • Anaerobic
  • Bioremediation
  • Denitrification
  • Nitrate
  • Nitrogen

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences(all)

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