Phytoremediation as a promising tertiary treatment strategy using water hyacinth to mitigate pollutants from industrial wastewater

Current treatment practices for the contamination of water and soil by cyanide and phenol are not effective at completely removing these contaminants. To address this gap, the present study investigated the absorption and removal of phenol and cyanide from synthetic wastewater using water hyacinth (Eichhornia crassipes), mimicking treated effluent of the coke oven industry with 100–1000 ppm phenol and 10–100 ppm cyanide. Over a 30-day treatment period, we monitored plant growth, pollutant removal efficiency under varying pH and concentrations, and water quality parameters. Notably, the highest removal rates were observed at neutral pH and at lower initial concentrations. At pH 7, the plants removed up to 93.85% of phenol at 100 mg/L and 87.9% of cyanide at 10 mg/L. In the experiments with varying concentrations of cyanide and phenol at pH 8.5, the highest removal was observed at 10 mg/L (86.26%) and 100 mg/L (83.64%) after 30 days. FESEM micrographs revealed plant tissue damage during pollutant exposure, indicating physiological impacts. Importantly, water hyacinth proved effective at extracting both phenol and cyanide from synthetic wastewater, although the plant’s growth rate was negatively affected by these pollutants. These findings highlight the promising role of water hyacinth as a tertiary treatment measure for industrial wastewater, bridging a gap in practical, reproducible, long-duration outdoor studies.