Phytoremediation Potential of Free Floating Plant Species for Chromium Wastewater: The Case of Duckweed, Water Hyacinth, and Water Lilies

Abstract

Chromium is the second most toxic metal in groundwater, soil, and sediments. Due to its large scale industrial utilization, it exist in various forms in the environment. The present technologies used to eliminate chromium are too expensive and not eco-friendly. Phytoremediation, which is low cost and eco-friendly technology for wastewater treatment was analyzed via Aquatic free-floating plants. This study was conducted to check the phytoremediation capability of three free-floating aquatic plants: Duckweed, Water lilies, and Water hyacinth for the removal of chromium (III) and (VI) in aqueous solutions. The aquatic plants were put in 15 L solution containing 1, 5, and 10 mg/L of Cr (III) and Cr (VI) for 14 days after two weeks acclimation period. The relative growth, tolerance index and chromium uptake by the three plants were measured. The concentrations of chromium in the samples were analyzed using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The results showed a significant increase (P < 0.05) in accumulation of chromium in the plant’s tissues. Maximum total accumulation of 322.57 and 82 mg/kg for plant treated with 10 mg/L for both solution of Cr (III) and Cr (VI) were obtained in Water hyacinth as compared to Duckweed with maximum accumulation of 169.43 and 37.29 mg/kg at 10 mg/L for both Cr (III) and Cr (VI) respectively. Water lilies show a relatively low removal performance with a maximum uptake of 160.82 and 28.78 mg/kg at 5 mg/L for both Cr (III) and Cr (VI) respectively. The relative growth of all plants increase with time but decrease for an increase in concentration of chromium. The study showed that Water hyacinth as an efficient candidate for phytoremediation of chromium compared with Duckweed and Water lilies.