Efficacy of permeable reactive barrier with different structures for the simultaneous removal of nitrate and MTBE from polluted water

Groundwater quality is essential for water supply, and the threat of groundwater pollution poses significant risks to society and the economy. This study investigates the removal of two common pollutants, nitrate and MTBE, using chemical reduction with zero-valent iron (ZVI) and adsorption with ZSM-5, respectively, within a permeable reactive barrier (PRB). Specifically, the research evaluates the performance of two structures: a material composition system that integrates reactive materials into a single barrier and a sequential barrier system with separate layers of ZVI and ZSM-5 for the simultaneous removal of these pollutants. The study investigates the effects of four variables: initial concentrations of nitrate and MTBE and dosages of ZVI and ZSM-5, each analyzed at five levels. The results demonstrate that the material composition system was more effective at nitrate removal, with an efficiency increase from 88% (using ZVI alone) to approximately 97%. However, this system exhibited a reduced MTBE removal efficiency, decreasing from over 99% (achieved with ZSM-5 alone) to around 86%, likely due to nitrate interference. Conversely, the sequential barrier structure outperformed the material composition system in MTBE removal, achieving a maximum efficiency of 95%. However, its nitrate removal efficiency was lower, at around 92%, which, while still acceptable, was less effective than that of the material composition system. In summary, the material composition system is more suitable for nitrate removal, whereas the sequential barrier system is better suited for MTBE removal. This study provides valuable insights into optimizing PRB designs for the simultaneous remediation of groundwater contaminants.