STP1232: Simulation of Microbiologically and Chemically Influenced Corrosion of Natural Sandstone

    Mansch, R
    Biologist and professor of microbiology, Institut für Allgemeine Botanik, Hamburg,

    Bock, E
    Biologist and professor of microbiology, Institut für Allgemeine Botanik, Hamburg,

    Pages: 14    Published: Jan 1994


    Abstract

    A test system for the simulation of a combined chemically (gaseous pollutants) and microbiologically (nitrifying bacteria) influenced corrosion on natural sandstone is presented. A high stone moisture was essential for the growth of nitrifying bacteria on test stones. Under optimum conditions, a nitrifying biofilm developed on the calcareous Ihrlersteiner green sandstone, reducing the evaporation from the stone surface. Biofilm cells adapted well to high concentrations of gaseous pollutants.

    The mean metabolic activities of ammonia oxidizers were 11 and those of nitrite oxidizers 30 times higher than mean values of samples from historical buildings.

    The microbiologically influenced nitric acid corrosion alone was stronger than the chemically influenced corrosion by a smog atmosphere (1065-μg/m3 sulphur dioxide, 850-μg/m3 nitric oxide, and about 450-μg/m3 nitrogen dioxide). While 72 μmol of calcium were solubilized per week of exposure to the smog atmosphere, 161 μmol of calcium per week were solubilized by the nitric acid produced by nitrifying bacteria.

    If gaseous pollutants were added, the microbiologically produced nitrite and nitrate were removed by the action of sulphur dioxide. Thus, the combined attack of nitrifying bacteria and gaseous pollutants did not result in increased corrosion.

    Keywords:

    building, air pollution, stone deterioration, corrosion, simulation, acceleration, biodeterioration, endolithic microorganisms, nitrifying bacteria, nitrification, nitric acid


    Paper ID: STP12936S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP12936S


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