Phytoremediation of Cadmium, Nickel and Lead from Wastewater by Limna gibba using Response Surface Methodology: Optimization Study

Abstract

Water pollution caused by toxic heavy metals remains a critical global issue, driving the search for sustainable and low-cost treatment technologies. This study explores a approach for removing cadmium (Cd), nickel (Ni), and lead (Pb) from industrial wastewater using phytoremediation with aquatic plants. Aquatic species Lemna gibba (Limna G.) was selected for its availability and potential as green remediation agent. In the phytoremediation experiments, synthetic wastewater solutions containing Cd, Ni, and Pb were exposed to the aquatic plant. Metals concentrations were monitored daily, while the percentage removal, was calculated to assess uptake efficiency. Optimization using response surface methodology (RSM) and central composite design (CCD) identified conditions that achieved high removal efficiencies across biomass load, exposure time, and initial concentrations. The plant, Limna G. exhibited the highest and fastest removal rates, particularly for Pb and Cd, classifying it as a hyperaccumulator. Overall, results demonstrate that the combined use of Limna G. for phytoremediation provides an effective, low-cost, and environmentally sustainable strategy for removing heavy metals from industrial wastewater. The dual use of biomass not only maximizes remediation efficiency but also reduces plant waste, offering a circular and eco-friendly treatment solution. The data was analyzed using the response surface methodology (RSM) in order to support activities that optimize the phytoremediation process. Three variables were included in a central composite design (CCD), which included 20 trials with 6 axial points and 6 repetitions at the center point. The most significant component in each experimental design response was determined by the analysis of variance (ANOVA). The prediction error between the experimental and predicted results for the removal of Cd, Ni, and Pb was 2.4, 1.8 and 0.3, respectively. This study recommended to use Limna gibba for the removal of Cd, Ni, and Pb from wastewater.