Eco-Friendly Floating Bio-Island for Cadmium Removal from Polluted Water Using Aquatic Macrophytes
Minhyo Tae
Canterbury School, New Milford, United States
Publication date: July 10, 2026
Canterbury School, New Milford, United States
Publication date: July 10, 2026
DOI: http://doi.org/10.34614/JIYRC2026I09
ABSTRACT
This study investigates an eco-friendly floating bio-island system using aquatic macrophytes for cadmium removal from polluted water. A small-scale hydroponic platform was constructed and planted with Eichhornia crassipes (water hyacinth), Hydrocotyle verticillata (water coin), and Hygrophila difformis (water wisteria). Synthetic wastewater containing nitrate as a background nutrient condition and 10 mM Cd²⁺ was used to evaluate cadmium-detection sensitivity, temporal removal kinetics, and tissue-specific accumulation. A colorimetric strip assay first established a cadmium detection limit of approximately 1 µM, indicating that the commercial kit is suitable for monitoring moderate to high contamination but not trace levels. Visual color changes after seven days confirmed that all three species could lower cadmium concentration, with water coin producing the greatest decolorization. Quantitative measurements over 8–20 days showed steadily increasing cadmium removal efficiencies, reaching roughly 82–90% for water coin, 78–82% for water hyacinth, and 72–78% for water wisteria by day 20. Tissue-distribution analysis revealed that more than three-quarters of accumulated cadmium was retained in roots, with stems and leaves containing only minor fractions. Mechanistic interpretation based on prior literature suggests that water coin’s superior performance may be related to dense root systems, phytochelatin-mediated detoxification, vacuolar sequestration, and restricted shoot translocation. Overall, the results demonstrate that a simple, low-cost floating bio-island can effectively sequester cadmium while confining most of the metal to root biomass. These findings highlight Hydrocotyle verticillata as a promising candidate for nature-based cadmium remediation of contaminated agricultural and urban water bodies. Future studies should directly measure nitrate, phosphate, and other nutrient parameters to evaluate whether this platform can also support nutrient removal.
This study investigates an eco-friendly floating bio-island system using aquatic macrophytes for cadmium removal from polluted water. A small-scale hydroponic platform was constructed and planted with Eichhornia crassipes (water hyacinth), Hydrocotyle verticillata (water coin), and Hygrophila difformis (water wisteria). Synthetic wastewater containing nitrate as a background nutrient condition and 10 mM Cd²⁺ was used to evaluate cadmium-detection sensitivity, temporal removal kinetics, and tissue-specific accumulation. A colorimetric strip assay first established a cadmium detection limit of approximately 1 µM, indicating that the commercial kit is suitable for monitoring moderate to high contamination but not trace levels. Visual color changes after seven days confirmed that all three species could lower cadmium concentration, with water coin producing the greatest decolorization. Quantitative measurements over 8–20 days showed steadily increasing cadmium removal efficiencies, reaching roughly 82–90% for water coin, 78–82% for water hyacinth, and 72–78% for water wisteria by day 20. Tissue-distribution analysis revealed that more than three-quarters of accumulated cadmium was retained in roots, with stems and leaves containing only minor fractions. Mechanistic interpretation based on prior literature suggests that water coin’s superior performance may be related to dense root systems, phytochelatin-mediated detoxification, vacuolar sequestration, and restricted shoot translocation. Overall, the results demonstrate that a simple, low-cost floating bio-island can effectively sequester cadmium while confining most of the metal to root biomass. These findings highlight Hydrocotyle verticillata as a promising candidate for nature-based cadmium remediation of contaminated agricultural and urban water bodies. Future studies should directly measure nitrate, phosphate, and other nutrient parameters to evaluate whether this platform can also support nutrient removal.
