Optimizing planting density for enhancing the synergistic effect of electrokinetic-phytoremediation in...

Electrokinetic-phytoremediation is an environmentally sustainable technology with significant potential for remediating petroleum-contaminated soils. The integration of vegetation to enhance electrokinetic remediation has been extensively studied. However, the impact of planting density on this combined approach remains poorly understood. This study investigates the effect of varying planting densities of tall fescue (Festuca arundinacea) on the efficacy of electrokinetic-phytoremediation for petroleum-contaminated soil. Over a 60-day remediation period, the combined electrokinetic and phytoremediation treatments at planting densities of 0.5, 1, 2, and 3 plants/cm² resulted in increased petroleum removal rates of 2.37%, 6.75%, 6.15%, and 5.45%, respectively, compared to electrokinetic remediation alone. Additionally, as planting density increased, soil water-soluble ion concentrations and the degree of compression in the soil colloid double layer thickness progressively decreased during the electrokinetic-phytoremediation process, while soil zeta potential and water-holding capacity initially increased before stabilizing. Planting density had a significant impact on the synergy between the plants and electrokinetics; the synergistic effect initially increased with density but then declined. The optimal planting density for tall fescue in electrokinetic-phytoremediation was found to be 1 plant/cm². This study offers both theoretical insights and empirical data to support the application of electrokinetic-phytoremediation for petroleum-contaminated soil remediation.