Feasibility of Using Bio-denitrification for Contaminated Groundwater

On our project site, we are experiencing a high level of nitrate in water. I would like to know if someone has installed bio-denitrification system for treating nitrate-contaminated groundwater.  If you have experience of nitrifying groundwater, please tell me which method were you using ? Please share your experience, especially with the bio-denitrification systems, I would like to know about the limitations and restrictions of using these systems. A couple of years ago, my Spanish friends, professionals, told me about the progress they have had in the processes of denitrification of groundwater. It would be great to know what new has come up in the recent years.