Dual-phase lead phytoremediation using <i>Nerium oleander</i> : integrating epuvalization hydroponics and soil systems for water-efficient decontamination

This study evaluates a dual-phase phytoremediation system integrating epuvalization hydroponics and potted soil cultivation for the concurrent remediation of lead (Pb) in water and soil. <i>Nerium oleander</i> was cultivated in two systems: a closed-loop hydroponic unit and potted soil, both irrigated with contaminated water (10 ppm Pb). In the hydroponic system, 99.8% of aqueous Pb was removed, reducing the concentration from 10 ppm to 0.02 ppb over 120 days. The soil system exhibited a 93.4% Pb retention (28.03 mg/kg), with significant root bioaccumulation (31.58 ± 9.93 mg/kg) and minimal translocation to shoots, confirming a phytostabilization mechanism. The plant demonstrated pronounced Pb tolerance, showing no significant (<i>p</i> > 0.05) inhibition of height, branch number, or biomass. This resilience is twice that of conventional species. Furthermore, the closed-loop epuvalization design reduced water consumption by 40% compared to conventional methods. These results validate the efficacy and water-saving advantage of this integrated system for the sustainable remediation of Pb-contaminated water and soil, highlighting the superior tolerance of <i>N. oleander</i>. This work establishes <i>Nerium oleander</i> as a robust candidate for dual-phase Pb remediation, combining hydroponic efficiency with soil stabilization, while offering a water-conserving solution for the treatment and agricultural reuse of wastewater in arid regions.