DISTRIBUTION OF MICROORGANISMS IN THE COURSE OF ARTIFICIAL RECHARGE OF GROUNDWATER AT BALTEZERS WATERWORKS, RIGA / Fördelning av mikrorganismer vid Baltezers anläggning för konstgjord infiltration i Riga
Artifcial recharge of groundwater is being used for drinking warer production in Latvia. The ultimate removal of organic matter from the surface water during artificial recharge of groundwater is accomplished by microrganisms living in the subsurface. In order to predict changes of water quality, more information about the disribution of microorganisms between infiltration ponds and producrion wells is necessary. During one year samples of the filrer sand below the infiltration ponds and water samples from the ponds and from the lake used for arificial recharge of groundwater were collected and analysed for the numbers of different heterotrophic bacteria, the total bacterial number and several sankary-bacteriological parameters. The results showed that most ofthe bacteria were attached to the filter sand material panicles. The discribution ofbacreria in the filter sand was heterogeneous.