Health & Environmental Research Online (HERO)


Print Feedback Export to File
4299995 
Journal Article 
Application of chemical oxidation to remediate HCH-contaminated soil under batch and flow through conditions 
Usman, M; Tascone, O; Rybnikova, V; Faure, P; Hanna, K 
2017 
Yes 
Environmental Science and Pollution Research
ISSN: 0944-1344
EISSN: 1614-7499 
24 
17 
14748-14757 
English 
28470496 
This is the first study describing the chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soil under water saturated and unsaturated flow through conditions. Soil contaminated with β-HCH (45 mg kg-1) and γ-HCH (lindane, 25 mg kg-1) was sampled from former lindane waste storage site. Efficiency of following treatments was tested at circumneutral pH: H2O2alone, H2O2/FeII, Na2S2O8alone, Na2S2O8/FeII, and KMnO4. Experimental conditions (oxidant dose, liquid/solid ratio, and soil granulometry) were first optimized in batch experiments. Obtained results revealed that increasing dose of H2O2improved the oxidation efficiency while in Na2S2O8system, maximum HCHs were removed at 300 mM. However, oxidation efficiency was slightly improved by FeII-activation. Increasing the solid/liquid ratio decreased HCH removal in soil samples crushed to 500 μm while an opposite trend was observed for 2-mm samples. Dynamic column experiments showed that oxidation efficiency followed the order KMnO4 > Na2S2O8/FeII > Na2S2O8whatever the flow condition, whereas the removal extent declined at higher flow rate (e.g., ~50% by KMnO4at 0.5 mL/min as compared to ~30% at 2 mL/min). Both HCH removal and oxidant decomposition extents were found higher in saturated columns than the unsaturated ones. While no significant change in relative abundance of soil mineral constituents was observed before and after chemical oxidation, more than 60% of extractable organic matter was lost after chemical oxidation, thereby underscoring the non-selective behavior of chemical oxidation in soil. Due to the complexity of soil system, chemical oxidation has rarely been reported under flow through conditions, and therefore our findings will have promising implications in developing remediation techniques under dynamic conditions closer to field applications.