Removal of nitrates from ground water by a hybrid process of biological denitrification and microfiltration membrane

Removal of nitrates from ground water in a hybrid process of biological denitrification and microfiltration is discussed. The most favourable parameters for a culture of denitrifying bacteria with respect to organic carbon/nitrate nitrogen (C/N) ratio and nitrate loading have been determined. A capillary module was selected on the basis of the amount of biomass retained during microfiltration. The optimum operational parameters of microfiltration on the selected membrane module were determined. The installation used for denitrification consisted of a bioreactor and a membrane module made of capillary fibres. This was fed continuously for several months with a fluid medium containing organic carbon (methanol), nitrates and biogenic elements.