Phytoremediation of Wastewater From Oil Well Drilling: Potential of Different Plant Species

This study evaluated the removal of contaminants present in wastewater from oil well drilling in the presence of three plant species: water hyacinth (Eichhornia crassipes), cattail (Typha domingensis), and purple fountain grass (Cenchrus setaceus "Rubrum"). The synthesized wastewater contained potentially toxic metals (Zn, Cu, and Cr) and representative hydrocarbons (naphthalene, hexane, and hexadecane) and it was applied in hydroponic systems operating in sequential batches. Agronomic, biochemical, and water quality variables were monitored periodically. The results indicated that C. setaceus had the best overall performance, indicating its absence of mortality, agronomic stability, and statistically significant removal of color, biochemical oxygen demand, total organic carbon, total carbon, and metals. The kinetics of chemical oxygen demand removal were faster in the presence of C. setaceus, with a higher reaction coefficient and better fit of the first-order model with residual (plateau) to the data. Although they promoted the removal of some pollutants, the performance of the treatments in the presence of T. domingensis and E. crassipes was inferior to that of the treatment with C. setaceus in terms of stability, vigor, and consistency of the results. It was concluded that C. setaceus has high tolerance to contaminated environments and potential for application in constructed wetland systems for the treatment of wastewater from well drilling and is a promising alternative for sustainable phytoremediation strategies.