Biological Treatment of Groundwater in Basins with Floating Filters–II. The Role of Microorganisms in Floating Filters

The role of certain types of bacteria is quite decisive in the formation of iron and manganese precipitates. Bacteria and other organisms participate in the precipitation of soluble iron and manganese in many different ways. The production of hydrogen peroxide seems to be an important phase in the formation of the precipitates. Bacteria produce hydrogen peroxide as an intermediate or an end product of metabolic processes (Gorlenko etal., 1983).

Iron and manganese bacteria are typical gradient organisms, growing in a sharp gradient between oxidized and reduced environments. Iron precipitating types are oligotrophic and manganese precipitating types need higher concentrations of organic compounds. Manganese precipitating bacteria are eutrophic.

Iron bacteria are sessile, and grow attached to the solid surfaces of filter media. Typical iron and manganese precipitating bacteria in groundwaters are Gallionella, Leptothrix, and Metallogenium.