The project considers the worldwide and local increase of nitrate concentrations observed in groundwater, as a result of the intensification of large scale animal farming in addition to fertilizer use and the application of residue of manure-fed biogas production plants on agriculturally used soils. Research is carried out towards nitrate removal from water resources, whereas the most promising approach, biological denitrification, is being studied. A combination of biological denitrification reactions with abiotic transformation processes is suggested to be an economically efficient strategy and possess a high efficiency in the framework of the self-purification of porous aquifers. In the frame of this project we also want to improve our understanding on the ecophysiology of microbes driving specific autotrophic denitrification. Based on this data we want to develop novel approaches for nitrate removal from groundwater systems making use of the functional traits of autotrophic denitrifiers in laboratory experiments and in field studies.