Oxidation by Fenton's reagent combined with biological treatment applied to a creosote-comtaminated soil

J Hazard Mater. 2009 Jul 30;166(2-3):594-602. doi: 10.1016/j.jhazmat.2008.11.108. Epub 2008 Dec 6.

Abstract

In this study, we investigated the feasibility of using Fenton oxidation to remove sorbed polycyclic aromatic hydrocarbons (PAHs) in aged soil samples with creosote oil from a wood preserving site. The optimal dosage of reagents was determined by a statistical method, the central composite rotatable experimental design. The maximum PAH removal was 80% with a molar ratio of oxidant/catalyst equal to 90:1. In general low molecular weight PAHs (3 rings) were degraded more efficiently than higher molecular weight PAHs (4 and 5 rings). The hydrogen peroxide decomposition kinetic was studied in the presence of KH(2)PO(4) as stabilizer. The kinetic data were fitted to a simple model, the pseudo-first-order which describes the hydrogen peroxide decomposition. The PAH kinetic degradation was also studied, and demonstrated that non-stabilized hydrogen peroxide was consumed in less than 30 min, whilst PAH removal continued for up to 24h. In a second part of the work, a combined chemical and biological treatment of the soil was carried out and shown to be dependent on the pre-oxidation step. Different reagent doses (H(2)O(2):Fe) were used (10, 20, 40, 60:1) in the pre-treatment step. An excess of hydrogen peroxide resulted in a poor biological removal, thus the optimal molar ratio of H(2)O(2):Fe for the combined process was 20:1. The combined treatment resulted in a maximum total PAH removal of 75% with a 30% increase in removal due to the biodegradation step. The sample with highest PAH removal in the pre-oxidation step led to no further increase in removal by biological treatment. This suggests that the more aggressive chemical pre-oxidation does not favour biological treatment. The physico-chemical properties of the pollutants were an important factor in the PAH removal as they influenced chemical, biological and combined treatments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Creosote / chemistry*
  • Feasibility Studies
  • Hydrogen Peroxide / chemistry*
  • Indicators and Reagents
  • Iron / chemistry*
  • Oxidation-Reduction
  • Polycyclic Aromatic Hydrocarbons / isolation & purification*
  • Soil Pollutants / chemistry
  • Soil Pollutants / isolation & purification*

Substances

  • Fenton's reagent
  • Indicators and Reagents
  • Polycyclic Aromatic Hydrocarbons
  • Soil Pollutants
  • Creosote
  • Hydrogen Peroxide
  • Iron