This work includes experimental examination of the hypothesis, affirming that bacteria’s, oxidising iron and manganese can grow in some Lithuanian water treatment and can increase the removal of iron and manganese substances from the water. The novelty is that the method of identification and cultivation of iron bacteria’s presented in the foreign scientific publications was improved and adapted to research of such micro-organisms existing in the quartz sand filter media in the Lithuanian equipment of water treatment plant. For the first time in Lithuania there was examined quantitative distribution of iron and manganese oxidising micro-organisms in the sand thin coating in filters of drinking water purification and were found regularity and dependency of iron bacteria’s activities on the main technological parameters in removal of iron and manganese substances from the water.

Iron and manganese – the main components in Lithuanian groundwater, not following requirements of norms regulate the water quality. Now the most advanced method for removal of the mentioned substances is non-reagent technologies, where the important role is the on biological oxidation. This work includes experimental examination of the hypothesis, affirming that bacteria’s, oxidising iron and manganese can grow in some Lithuanian water treatment and can increase the removal of iron and manganese substances from the water. The novelty is that the method of identification and cultivation of iron bacteria’s presented in the foreign scientific publications was improved and adapted to research of such micro-organisms existing in the quartz sand filter media in the Lithuanian equipment of water treatment plant. For the first time in Lithuania there was examined quantitative distribution of iron and manganese oxidising micro-organisms in the sand thin coating in filters of drinking water purification and were found regularity and dependency of iron bacteria’s activities on the main technological parameters in removal of iron and manganese substances from the water.