Chemical Oxidation by Sodium Persulphate for the Treatment of Contaminated Groundwater. Laboratory Tests

Abstract

This study was focused on the remediation of groundwater contaminated by 1,4-dichlorobenzene (DCB), 1,2-dichloropropane (DCP), benzene and iron. The aim of the research project was to evaluate the feasibility of chemical oxidation by sodium persulphate through laboratory tests. On the basis of previous results obtained by the authors on artificially contaminated groundwater, some batch tests have been carried out on water samples from the site. It was observed that high values of chemical oxygen demand (COD) and low content of dissolved iron led to decreasing removal efficiencies, due to the competition for the persulphate exerted by the natural organic matter in groundwater and to the lack of the catalyst, respectively. Further tests have been performed by varying the concentration of iron in order to determine the influence of the catalyst on the removal process. Such tests allowed to set the optimal iron dosage under the experimental conditions adopted. Moreover, the Vibrio fisheri ecotoxicity test have been conducted, suggesting that the addition of persulphate and the reaction by-products did not lead to an increase of the toxicity level.