Washing of Coastal Sediment from Mboppi River (Douala, Cameroon) Polluted by Polycyclic Aromatic Hydrocarbons (PAHs) using Sodium Dodecyl Sulfate (SDS)

Abstract

Because of their hydrophobic nature, polycyclic aromatic hydrocarbons (PAHs) have low solubility in an aqueous medium and strong adsorption on soils and sediments, resulting in their persistence in the environment. This work was undertaken with the goal of having enough data to set up a stirred reactor, which will be used in the treatment of soils and sediments polluted by hydrocarbons while preserving the environment. To this end, sediment samples from the Mboppi were taken successively during the rainy season and the dry season. Gas chromatography coupled with a flame ionization detector (CPG/FID) was used to carry out a preliminary analysis of the samples. Then, chemical washing treatment tests using sodium dodecyl sulfate (SDS) were carried out on the most polluted sediment sample using a complete factorial plan with three factors (temperature, speed, and duration of agitation) to determine the parameters that influence depollution yields. It appears that the temperature (80 °C), the speed (1000 rpm), and the stirring time (40 min) give a better desorption yield (85.79%). The results show that SDS can effectively and significantly reduce the content of PAHs in sediments. The reduction of HMW-PAHs was observed, with the highest percentage (82.69%) obtained for 6 ring PAH under the same conditions. The environmental health risk assessment was reduced from 74.34 to 24.41, thus showing how far the washing with SDS is satisfactory.