The Method Study On Remediation Of TCE DNAPLs By Fenton-like Oxidation

Trichloroethylene (TCE) is one of chlorinated solvents and the most extensive contaminants in soil and groundwater. So source area of TCE widely exists and dissolves constantly in the groundwater. For the problem, some treatment methods of TCE`s source area were compared and fenton-like oxidation in-situ chemical oxidation was studied in the proposed thesis.In the proposed thesis, , the relationship between the speciation of ferreous mineral and the removal rate of TCE was discussed by the batch experiments and column experiments, and the quantity and concentration of oxidant were studied. Finally, the catalysis mechanism of natural ferreous mineral in the fenton-like oxidation was induced.In the batch experiments, the fenton-like oxidation experiments were designed by using minerals as the catalyst, such as hematite, hematite, siderite, natural sand, quartz, FeSO4 and glass beads. The results showed that any morphology of ferreous mineral can be used as catalysts in the fenton-like oxidation system. The catalytic efficiency of Fe(â…¡) was better than that of Fe(â…¢), and natural sand containing ferreous mineral was also a kind of catalysts. Then FeSO4 can be replaced with natural sand in the fenton-like oxidation. Additionally, the catalytic efficiency of ferreous mineral depends on percentages (mass) of Fe(â…¡) in the fenton-like oxidation.In the column experiments glass bead, river sand collected from Tong Zhou and Shen Yang were used as the filling materials. Simulation of the contaminated source area in the groundwater was studied by injecting TCE. The fenton-like oxidation was carried on by injecting H<sub>2</sub>O<sub>2</sub> as oxidant. By analyzing the relationship between different concentrations of H<sub>2</sub>O<sub>2</sub> solution and removal rates of TCE, the results indicated that removal rate of TCE reached more than 90% when the percentage of H<sub>2</sub>O<sub>2</sub> solution is 1% (g/mL). The relationship between different concentrations of H<sub>2</sub>O<sub>2</sub> solution and removal rate of TCE is that average reaction rate is 0.27gTCE/(gH<sub>2</sub>O<sub>2</sub>*h) for Tong Zhou`s river sand and 0.21gTCE/(gH₂O₂*h) for Shen Yang`s river sand. Cl- mol mass balance and the chromatogram of samples demonstrated TCE was degraded to CO2 and H2O.In conclusion, ferreous mineral could be not only as catalyst, but also as ractant in the degradation of TCE. Under the natural condition and with enough oxidation, 1g Fe(â…¢) could be sustainable used as the catalyst about 1104 hours ( 46 days), and could remove 2.60g TCE. On the other hand, 1g Fe(â…¡), can be sustainable used ) as the catalyst about 2720 hours (113 days), and 12.34g TCE was removed.