Application of X-ray diffraction for studies on microbially induced metal corrosion
Alicja Hryniszyn, Beata Cwalina* – Department of Environmental Biotechnology, Faculty
of Energy and Environmental Engineering, Silesian University of Technology, Gliwice, Poland

Please cite as: CHEMIK 2015, 69, 8, 455–462

Metals and their alloys often undergo corrosion. In some cases it is related to activity of microorganisms forming biofilm on the metal surface. Such a situation is also typical for drinking water supply system. Cells and the organic matter they produce collect in a places, where water continuously acts on pipe walls. Such conditions promote the growth and proliferation of microbes [1 – 3]. Microbes present in water mains are adapted to low content of nutrients in drinking water (less than 2 mg of organic matter per 1 l of water) and are very hard to manage [4]. The presence of bacteria in water supply networks brings a number of problems, e.g. increased consumption of disinfectants, which means higher water treatment costs [5, 6]. The biofilm may also serve as a reservoir of pathogenic microbes [7], including coliforms. Search for their potential source has lead to the conclusion they must have been present in biofilms formed on pipe walls of drinkable water supply system. When released from the biofilm, they entered the water and were detected as suspended (planctonic) bacteria [7]. The bacteria also contribute to the corrosion of piping [8, 9]. This results in decrease of their strength, as well as generation of favourable conditions for growths of other microorganisms on the surface of the corroded porous surfaces [3, 6]. Pipe corrosion among others leads to releasing iron compounds into water, which causes its turbidity and deterioration of organoleptic properties [10, 11]. Bacteria may have direct effect on the quality of supplied water by changing its colour related to the content of compounds containing iron and/or other metals (their presence may be a result of bacterial metabolic activity, e.g. Galionella genus) as well as unpleasant odour and taste (e.g. due to the presence of hydrogen sulphide produced by sulphate reducing bacteria; RBS) [3, 10, 12]. Biofilm generation in water supply network may also lead to hydraulic losses due to the increase of pipe wall roughness and deposition on them insoluble compounds of iron and other metals [5, 12, 13].

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