Oxidation by Fenton's reagent combined with biological treatment applied to a creosote-comtaminated soil.
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.
Valderrama
C
C
Mining Engineering and Natural Resources Department, EPSEM, UPC, 08240 Manresa, Spain. cesar.alberto.valderrama@upc.edu
Alessandri
R
R
Aunola
T
T
Cortina
J L
JL
Gamisans
X
X
Tuhkanen
T
T
D000327:Adsorption; D003407:Creosote / Q000737:chemistry*; D005240:Feasibility Studies; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007202:Indicators and Reagents; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification*; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification*
C045076:Fenton's reagent; D007202:Indicators and Reagents; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; D003407:Creosote; D006861:Hydrogen Peroxide; D007501:Iron