Biological denitrification of groundwater

Nitrate concentrations in groundwater have increased in many areas of the world. This causes serious concerns because of the link found between nitrate and the blue-baby syndrome, and of the possible formation of carcinogenic compounds in the digestive tract. Biological denitrification, bacteria-mediated reduction of nitrate to nitrogen gas, is a method used in the treatment of nitrate contaminated groundwater. The denitrifying microorganisms require carbon and energy substrates which may be organic or inorganic compounds. Treatment can take place in the aquifer (in situ treatment) or in above ground reactors. Numerous biological denitrification processes have been reported; this paper reviews some of this work and studies in progress in the author's laboratory. The choice of a biological denitrification system has to be considered on an individual basis. Although preventive measures are curbing the problem in some developed countries, nitrate pollution is still on the rise in many other countries. Innovative, low-cost biological denitrification processes are specially needed in developing countries.