Optimization of Soil Aquifer Treatment by Chemical Oxidation with Hydrogen Peroxide Addition

Trace organic compounds (TrOCs), mostly found in secondary effluents, have a potential impact on the environment, affecting surface water, groundwater, and especially aquatic ecosystems. The present study focuses on oxidation of five selected TrOCs in column experiments, by simulating Soil Aquifer Treatment (SAT) integrated with Fenton-like reaction, using Granular Ferric Hydroxide (GFH) as a catalyst. In order to determine the effectiveness of TrOCs removal from water with this approach, some experiments have been carried out with ultrapure water, containing different target compounds at pH = 6, using different dosages of hydrogen peroxide and catalyst. In this study the optimal concentration of H2O2 for TrOCs removal has been found to be 200 mg/L; however, observed overall removal has been low for each target compound. Moreover, little increase has been observed in chemical oxidation of micro-pollutants through raising the catalyst's dosage. For an optimum concentration of hydrogen peroxide,the removal of 33%, 34%, 28%, 29%, and 35% has been observed for benzotriazole, carbamazepine, phenytoin, primidone, and meprobamate, respectively in 5 h with a hydraulic retention time of 3 h. Therefore, this treatment scheme might not be a promising option for oxidation of secondary effluents. Thus, other treatment options, such as pH decrease, recirculation of effluent through columns to increase the hydraulic retention times, other types of catalyst, and higher dosage of hydrogen peroxide need to be considered for more efficient removal of TrOCs within SAT, integrated with Fenton-like reaction.