Coupling electrokinetic remediation with phytoremediation for depolluting soil with petroleum and the use of electrochemical technologies for treating the effluent generated

This work aims to investigate the enhancement of the efficiency of phytoremediation (phytoR) by electrokinetic remediation (ER) by using graphite electrodes to depollute soil contaminated with petroleum. It was focused on the effects of electric fields (by applying direct current (DC) of reversal polarity (RP)) as well as the growth of sunflower plants after soil remediation. In this case, five experimental setups were used, phytoR, ER and electro-phytoremediation (ER-PhytoR) by supplying DC (ER-PhytoR-DC) or RP (ER-PhytoR-RP). Regarding the total petroleum hydrocarbon (TPH) removal, it was more efficient for the ER-phytoR-RP carried out at 1 V cm(-1) after 20 d where microbial degradation in the rhizosphere and organic compounds transport through the soil associated to the RP (contributing to avoid the acidity and alkaline fronts in the soil), were the key operating parameters. Results clearly showed that the application of RP favoured the germination, growth of plants and high TPH removal after 20 d. It was also demonstrated by higher biomass production achieved at different treatments; 5.22 g for phytoR, 1.137 g for ER-phytoR-DC and 5.89 g for phytoR-ER. Finally, two diamond based-electrochemical technologies (anodic oxidation (AO-H2O2) and electro-Fenton (EF)) have been used for treating the effluents generated by soil decontamination to eliminate the dissolved organic matter.