Permeable reactive barriers for in situ remediation of nitrate-contaminated groundwater: A review

Groundwater contamination by nitrate has become a global issue, mainly caused by the excessive use of fertilizers. Thus, several technologies, such as permeable reactive barriers (PRBs), have become appropriate, efficient, and sustainable in-situ technology for treating contaminated groundwater. Biological denitrification is the main mechanism for nitrate removal in groundwater. Therefore, temperature, pH, denitrifying bacteria, reactive material, and PRB design are critical factors for nitrate remediation in groundwater. Recently, agricultural residues have been proposed as novel reactive materials since they can be a source of organic carbon for the biostimulation of this process due to their cost, accessibility, and removal efficiency. In addition, PRBs behavior can be predicted by modeling and simulation before the in situ application. This review article analyzed the studies published during the past five years (2018–2022). It was found that 37.73% of the studies were laboratory-scale, employing leaching, batch, and column tests. However, 13.21% of the articles pertained to in situ PRB studies for nitrate remediation in groundwater. Therefore, work on the long-term performance of PRBs for nitrate removal and their in-situ performance is scarce.