This study is a state-of-art of nitrate removal using nanoscale zero valent iron in groundwater. In this paper, the options to remediate groundwater contamination are reviewed : biological denitrification by heterotrophs and autotrophs bacteria. Moreover, the advantages and drawbacks of nZVI are mentionned and explained. Indeed : nZVI are very efficient to remove nitrate from groundwater, but tend to agglomerate or to be oxidized into ferrous oxides that create a layer of passive barrier onto iron surface. Consequently, the nitrate removal rate is decreasing due to a low mass transfer. But nZVI can be stabilized to improve their performances. Some studies worked on associate microbial denitrification and chemical nitrate removal. A synergy can exist between these two mechanisms and increase the nitrate removal efficiency. To reach the in-situ denitrification and chemical nitrate removal, it is necessary to understand the mechanisms in continuous flow. That is why several studies worked in packed columns. However, this domain is quite new and it requires more researches.