Excessive nitrogen fertilization leads to a high nitrate concentration in plants (vegetables). Nitrates enter the human body via food and convert to nitrites which have a toxic effect. With the aim of preserving biodiversity, plant health, human health and a series of other ecological factors, microbial processes; denitrifications, Dissimilatory Nitrate Reductions to Ammonium (DNRA) and the anaerobic ammonium oxidation (annamox) will be presented in this paper. These are the three key processes for reducing nitrates in the soil with the goal of maintaining balance.