REMOVAL OF NITRATES FROM DRINKING-WATER BY BIOLOGICAL DENITRIFICATION

Biological methods for drinking water denitrification are reviewed. The review is focussed on biotechnologies which have been applied on a full-scale (both autotrophic and heterotrophic). The possibility of autotrophic denitrification on mixed bed of elemental sulphur and limestone, and denitrification using hydrogen bacteria is briefly outlined. The major part of the paper is devoted to technologies which utilize heterotrophic denitrifying microorganisms. The technologies are divided into three groups, according to the heterotrophic denitrification process design: (1) fixed bed reactors, (2) fluidised bed reactors, and (3) in-situ process. Advantages and disadvanteges of the processes are discussed. The authors' full-scale experimental experience with fixed bed reactors and in-situ denitrification are presented.