This study investigates the enhanced performance of a constructed wetland (CW) system composed of silty-sandy soil and Chrysopogon zizanioides (vetiver), integrated with electrokinetic treatment, for the simultaneous removal of lead (Pb) and doxycycline (DOXY) from wastewater. Preliminary batch adsorption experiments, designed using response surface methodology (Box–Behnken Design), were conducted to optimize soil dosage (10–40 g/L), contact time (30–120 min), and initial contaminant concentration (2–10 mg/L). These optimized parameters were subsequently applied in the CW experiments, demonstrating removal efficiencies of 95%–99% for Pb and 85%–96% for DOXY. Adsorption kinetics followed the pseudo-second-order model (R2=0.96), and equilibrium behavior fit the Freundlich isotherm (R2=0.98), indicating multilayer chemisorption on heterogeneous surfaces. Electrokinetic rejuvenation reduced residual concentrations in the wetland bed soil (Pb: 0.435 to 0.110 mg/g; DOXY: 0.296 to 0.103 mg/g) and increased uptake by vetiver, with maximum accumulation in stems (Pb: 0.189 mg/g; DOXY: 0.056 mg/g). Electrokinetic treatment induced an acidic shift in anode pH, while the cathode remained alkaline. The initial bed exhaustion time was 55 days for DOXY and 105 days for Pb. After rejuvenation, the system achieved removal efficiencies of 86.8% for Pb and 78.1% for DOXY. These results demonstrate that electrokinetic-enhanced vetiver-based CWs offer a sustainable and low-cost solution for long-term contaminant attenuation and wetland life span extension, with significant implications for wastewater treatment in resource-constrained settings.
Adhikary et al. (Sun,) studied this question.