Assessment of the Phytoremediation Potential of Water Hyacinth (Eichhornia crassipes) for the Removal of Heavy Metals from Spent Oil-simulated Polluted Water
Peter Okpagu Abua
University of Cross River State, Calabar, Nigeria.
Peter O. Etinosa-Okankan
University of Cross River State, Calabar, Nigeria.
Jeremiah Chukwuebuka Anigbo *
University of Cross River State, Calabar, Nigeria.
Deborah Praise Abua
University of Cross River State, Calabar, Nigeria.
Akinsheye Joshua Akinsheye
University of Cross River State, Calabar, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Heavy-metal contamination of aquatic environments poses persistent ecological and public-health concerns because metals can remain in water and accumulate in biological systems. Conventional treatment methods may be costly and generate secondary waste, creating interest in plant-based remediation approaches. Water hyacinth (Eichhornia crassipes) has potential for phytoremediation because of its capacity to absorb and accumulate dissolved heavy metals from contaminated water. This study assessed the potential of water hyacinth (Eichhornia crassipes) in the phytoremediation of heavy metals (HMs) from simulated spent-oil-contaminated water under controlled experimental conditions. The study determined the concentrations of nickel (Ni), iron (Fe), lead (Pb), cadmium (Cd), and chromium (Cr) in slightly, moderately, and highly polluted water after treatment with E. crassipes. Healthy E. crassipes plants were obtained from Anagthigha in Calabar South LGA, Cross River State, and acclimatised before being introduced into simulated contaminated water. Water samples were collected on days 0, 7, and 14, while the plant samples were collected at the end of the experiment. Heavy metal concentrations were determined using an atomic absorption spectrophotometer (AAS) following appropriate sample preparation and acid digestion procedures. The data obtained were subjected to statistical analysis, specifically one-way analysis of variance and Tukey’s post hoc test, with significance accepted at p < 0.05. The results showed a decline in the concentrations of Ni, Fe, Pb, Cd, and Cr across the simulated polluted water test groups, demonstrating the phytoremediating ability of E. crassipes to bioaccumulate heavy metals. After 14 days, Ni removal efficiencies were 9.34%, 13.11%, and 31.07% in slightly, moderately, and highly polluted water, respectively, while Fe removal efficiencies were 11.90%, 16.78%, and 29.48%. Pb removal efficiencies were 8.70%, 28.89%, and 28.26%, whereas Cd recorded 7.35%, 12.31%, and 33.06%. Chromium removal efficiencies were 9.35%, 14.15%, and 31.48%, respectively. Metal accumulation was also detected in the leaf, stalk, and root tissues of E. crassipes. The findings demonstrate that Eichhornia crassipes has the potential as a low-cost, environmentally friendly phytoremediation agent for reducing Ni, Fe, Pb, Cd, and Cr in polluted water.
Keywords: Water hyacinth, Eichhornia crassipes, phytoremediation, heavy metals, spent-oil contamination, bioaccumulation, polluted water