Abstract

The molecular complexity and the low solubility of petroleum hydrocarbon residuals in weathered soil hinder bioremediation as a clean-up strategy. Pretreatment with advanced oxidation, such as with ozone gas (O3), is a means to transform recalcitrant organics to more biodegradable forms. The efficacy of gas-phase ozone for enhancing the biodegradability of heavy residual petroleum hydrocarbons in weathered soil was tested. Ozonating soil containing ~1% (w/w) residual petroleum hydrocarbons with a dose of 6 kg ozone/kg initial total petroleum hydrocarbons (TPHs) achieved nearly 50% TPH reduction, simultaneous with a >20-fold increase in soluble chemical oxygen demand, but with a ≤12% loss of total organic carbon. TPH molecules were converted to partly oxidised products, ten of which were identified as n-monocarboxylic acids, which were readily biodegraded, and ozonation resulted in a fourfold increase in 5-d biochemical oxygen demand (BOD5). BOD5 results after ozonation were the same with or without a microbial seed, which suggests that bioaugmentation is likely not necessary after ozonation. Deoxyribonucleic acid sequencing over the time course of the BOD5 tests showed increased diversity and changes in predominant genera, both of which underscore that ozonation made the heavy hydrocarbons readily biodegradable for soil bacteria.

Original languageEnglish (US)
Pages (from-to)7-17
Number of pages11
JournalJournal of Environmental Engineering and Science
Volume11
Issue number1
DOIs
StatePublished - Jun 1 2016

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Keywords

  • Environment
  • Pollution
  • Safety & hazards

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Environmental Science(all)

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