Application of in situ permeable reactive barrier technology for the remediation of nitrate contaminated groundwater

Groundwater is one of the most available resources in Iran and other parts of the world. Nitrate contamination ofgroundwater resources due to consumption and improper management of nitrogenous fertilizers, is one of the importantenvironmental and agricultural problems in present. Removing nitrates from contaminated water is one of the mostimportant environmental issues. Denitrification methods of groundwater are divided into two general categories: In-Situand Ex-Situ. In-Situ methods, treatment pollution in the site (eg, aquifer) and Ex-Situ methods extract pollution fromthe site and perform filtration out of site (eg the earth surface). Pumping and feeding system is one of the most commonmethods of treating Ex-Situ. In this system, after pumping water from wells, water filtered by using methods such asreverse osmosis and electrodialysis, and then injected through well into the groundwater. But this process requiressophisticated equipment, skilled operators and high energy consumption, which lead to an expensive treatment process.But In-Situ remediation methods are more economical compared to Ex-Situ methods and do not have the In-Situmethods problems. So the extention of groundwater nitrate pollution and expensive Ex-Situ method, lead to moretendency for using of In-Situ methods. Permeable reactive barrier (PRB) is one of the best technologies of In-Situremediation technique. The general concept of this technology, is putting the permeable barrier in the direction ofground water that contaminated with nitrate. So the mass of contaminants passes under the influence of naturalhydraulic gradient, and permeable barrier can treatment it. For building permeable barrier, a trench drill deep enoughunderground and then fill with reactive materials. During passing of water from the Permeable reactive barrier (PRB),contamination reacts with the material located within the barriers and purified water comes out the other side of thebarrier. In this study, the Permeable reactive barrier (PRB) technology for groundwater denitrification is discussed. Thisstudy included introduction of groundwater pollution sources, technology PRB, how do groundwater in situdenitrification, and reviewing the studies in the field of PRB, design and installation of the PRB, advantages andlimitations of the PRB.

Keywords:

Groundwater pollution , Nitrate removal , Permeable Reactive Barrier , In situ denitrification