Simultaneous addition of surfactant and oxidant to remediate a polluted soil with chlorinated organic compounds: Slurry and column experiments

The inadequate management of wastes associated with chlorinated organic compounds (COCs) has become a huge environmental problem. Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) was studied as a successful technique to remediate polluted sites. This work investigated the reaction between an aqueous solution of nonionic surfactant (Emulse-3 (R)) and an oxidant (sodium persulfate activated with NaOH) with a real polluted soil with a complex mixture of COCs from lindane liquid wastes. Two experimental setups were used. In the first one, the reactions were carried out in batch mode under slurry conditions using different surfactant concentrations (0-10 g center dot L-1), 210 mM of persulfate and 420 mM of NaOH with an aqueous to soil ratio VL/W = 10 L center dot kg-1. The runs were carried using a column loaded with the soil in the second experimental setup. The solution of surfactant, oxidant and activator was put in contact with soil in four pore volumes with a ratio aqueous to soil ratio VL/W = 0.2 L center dot kg-1. Under these experimental conditions, the surfactant addition improved the reduction of COCs compared with the application carried out without surfactant, from 40.1% to values of conversion of 64.8 - 90.4%. However, an excess of surfactant hindered the COCs oxidation and increased the unproductive consumption of the oxidant, resulting in an optimal value of surfactant in the aqueous phase (1-2 g center dot L-1). A remarkable drop in the surfactant concentration in the aqueous phase and COCs solubilized was noticed in column runs due to the surfactant adsorption.

Automated summary

This study investigated the application of Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) technique for the remediation of polluted soil with chlorinated organic compounds (COCs). The results showed that the addition of an appropriate amount of surfactant improved the reduction of COCs, while an excess of surfactant hindered the oxidation reaction and increased the unproductive consumption of the oxidant.