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51316-7278-Molecular Microbiological Methods to Investigate Microbial Influenced Corrosion in Fully Integrated Kraft Pulp and Paper Mills

Corrosion in modern paper mills accounts for 30+% of maintenance expenses. Molecular microbiological methods (MMM): • Quantitative polymerase chain reaction (qPCR) and QuantArray were employed to examine MIC at four paper mills each with unique process characteristics and construction materials in the affected areas. 

Product Number: 51316-7278-SG
ISBN: 7278 2016 CP
Author: Dora Ogles
Publication Date: 2016
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Corrosion in the modern paper mill accounts for as much as 30% of maintenance expenses. Although not always recognized as the dominant mechanism MIC is a significant contributor to corrosion related deterioration and eventual loss of equipment despite the seemingly inhospitable conditions for microbial growth. Molecular microbiological methods (MMM) including quantitative polymerase chain reaction (qPCR) and QuantArray were employed to examine MIC at four paper mills each with unique process characteristics and construction materials in the affected areas. Despite demonstrating effective treatment of raw process water qPCR quantification of total bacteria and specific MIC associated microbial groups revealed at times growth of substantial and diverse microbial populations within the system which had not been identified with traditional cultivation based methods. Moreover while microbial populations differed considerably between locations and facilities qPCR quantification of several microbial groups highlighted their roles in MIC. At most facilities including one experiencing corrosion of 6% molybdenum stainless steel iron oxidizing bacteria were detected at times at concentrations as high as 1.00E+08 cells/g. The actions of iron oxidizing bacteria were confirmed x-ray diffraction (XRD) analysis that demonstrated substantial production of iron oxyhydroxides including hematite maghemite goethite and akaganeite. Fermenting bacteria were also routinely detected at substantial concentrations. In addition to more direct impacts volatile fatty acids (VFAs) and hydrogen produced during fermentation can support growth of other anaerobic microorganisms linked to MIC including sulfate reducing bacteria (SRB) and methanogens. Consistent with biofilm maturation and growth of anaerobic bacteria SRB and methanogens were detected in some solid phase samples. Overall the qPCR results suggest biomass growth within the system biofilm formation the actions of iron oxidizing bacteria and tubercle formation followed by proliferation of fermenters and eventually SRB and methanogens.

Key words: MIC, MMM, qPCR, iron oxidizing bacteria, pulp and paper, downloadable

 

Corrosion in the modern paper mill accounts for as much as 30% of maintenance expenses. Although not always recognized as the dominant mechanism MIC is a significant contributor to corrosion related deterioration and eventual loss of equipment despite the seemingly inhospitable conditions for microbial growth. Molecular microbiological methods (MMM) including quantitative polymerase chain reaction (qPCR) and QuantArray were employed to examine MIC at four paper mills each with unique process characteristics and construction materials in the affected areas. Despite demonstrating effective treatment of raw process water qPCR quantification of total bacteria and specific MIC associated microbial groups revealed at times growth of substantial and diverse microbial populations within the system which had not been identified with traditional cultivation based methods. Moreover while microbial populations differed considerably between locations and facilities qPCR quantification of several microbial groups highlighted their roles in MIC. At most facilities including one experiencing corrosion of 6% molybdenum stainless steel iron oxidizing bacteria were detected at times at concentrations as high as 1.00E+08 cells/g. The actions of iron oxidizing bacteria were confirmed x-ray diffraction (XRD) analysis that demonstrated substantial production of iron oxyhydroxides including hematite maghemite goethite and akaganeite. Fermenting bacteria were also routinely detected at substantial concentrations. In addition to more direct impacts volatile fatty acids (VFAs) and hydrogen produced during fermentation can support growth of other anaerobic microorganisms linked to MIC including sulfate reducing bacteria (SRB) and methanogens. Consistent with biofilm maturation and growth of anaerobic bacteria SRB and methanogens were detected in some solid phase samples. Overall the qPCR results suggest biomass growth within the system biofilm formation the actions of iron oxidizing bacteria and tubercle formation followed by proliferation of fermenters and eventually SRB and methanogens.

Key words: MIC, MMM, qPCR, iron oxidizing bacteria, pulp and paper, downloadable

 

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