Journal of Global Ecology and Environment

The activities of crude oil exploration and production have led to severe contamination of the soil and water environment in the Niger-Delta area of Nigeria. This study aimed to investigate the efficiency of pollutant removal and phytokinetic of crude oil-contaminated wastewater (COCW) using water hyacinth (Eichhornia crassipes). Crude oil-contaminated wastewater was treated for 6 weeks. The tested samples were collected weekly for physicochemical analysis, and the control sample was analysed at the beginning and end of the study. The following parameters were analysed, biological oxygen demand (BOD₅), chemical oxygen demand (COD), dissolved oxygen (DO), total petroleum hydrocarbon (THC), lead (Pb²⁺), iron (Fe²⁺), total suspected solids (TSS), and total dissolved solids (TDS) using American Public Health Association (APHA) standard methods.

The results showed that, the percentage reduction ranged from 87.8% for COD to 99.1% for Fe²⁺, while the percentage improvement was 14.7% for pH and 96.6% for DO. Also, the maximum percentage reduction in BOD₅, COD, THC, Fe, and Pb was 86.3%, 87.8%, 93.9%, 99.1%, and 88%, respectively. The first-order kinetic model best fit the experimental data, and R² ranged from 0.97 to 0.99. Besides, the kinetic rate k of COD, BOD₅, Fe, Pb, and THC reduction ranged from 0.03 wk^-1 to 0.89 wk^-1, and the order is Fe²⁺>BOD₅>Pb>THC>COD. The water quality parameters of the treated COCW after 6 weeks of phytoremediation were within or below the acceptable water quality standards for discharged effluent specified by WHO, 2006 and NESREA as maximum permissible limits. The water hyacinth (Eichhornia crassipes) has excellent potential in remediating crude oil-contaminated wastewater. The first-order kinetic model gave a good fit and adequately described the kinetics of pollutants removal for the phytoremediation process.