BIOLOGICAL WATER DENITRIFICATION - A REVIEW

Different methods of biological denitrification of drinking water as well as the microbiology and stoichiometry of the process are reviewed. Autotrophic bacteria oxidizing anorganic compounds or heterotrophic species oxidizing organic materials can perform denitrification. Generally, autotrophic bacteria grow slowly and denitrification rates are lower, whereas contamination of denitrified water with organic materials requires extensive posttreatment in the heterotrophic processes. Most full-scale applications make use of heterotrophic processes due to their efficiency, high specific denitrification rate, and operational simplicity. Both processes have been tried also in situ using soil infiltration, but underground phenomena remain difficult to control. In situ denitrification is applicable only under certain geological conditions.