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Biomedical subjects

B H Olesen

Publications and source records attributed to B H Olesen.

4 recordsLinked to original sources
PubMed2005

Microbial diversity in biofilms from corroding heating systems.

Culture-independent investigations of the bacterial diversity and activity in district heating systems with and without corrosion did not make it possible to relate one group of microorganisms with the observed corrosion. Fluorescence in situ hybridization by oligonucleotide probes revealed the dominance of beta-proteobacteria, sulphate reducing prokaryotes and alpha-proteobacteria. Analysis of a clone library from one Danish heating (DH) system showed that the most sequences formed two clusters within the alpha-proteobacteria affiliated to the families Rhizobiaceae and Acetobacteraceae and two clusters within the beta-proteobacteria belonging to the family Comamonadaceae. Functional groups were determined by microautoradiography showing aerobic and anaerobic bacteria (sulphate reducing and methanogenic bacteria). The corrosion study showed that pitting corrosion rates were five to ten times higher than the general corrosion rates, suggesting the presence of biocorrosion. The results indicate that several bacterial groups could be involved in corrosion of DH system piping including sulphate reducing prokaryotes, Acidovorax (within the beta-proteobacteria), methanogenic bacteria and others.

Bacteria↗
PubMed2004

MIC mitigation in a 100 MW district heating peak load unit.

During inspection of AISI316 stainless steel plate heat exchangers in a district heating peak load unit, localised corrosion attacks along with indications of microbiological activity were found on the boiler side beneath patches of sturdy black deposits. Bacteria and sulphide were detected within black deposits. Thorough investigation of the boiler system revealed several incidents of localised corrosion on low alloy steel along with deposits of organic matter and bacteria primarily in places with stagnant water or places operating at a low flow rate. A relatively large amount of bacteria was detected within the system, primarily in deposits and around corrosion sites. The observations suggested the combination of deposits and bacterial activity, being the major reason for the observed corrosion. Prior to the investigation, the boiler system had operated with cat-/anion-exchanged, de-aerated water for 3 years, during which the water fulfilled strict chemical limits set to minimise corrosion. Based on these findings, the system has been modified in order to minimise the risk of microbiologically influenced corrosion and a monitoring program for fouling and corrosion has been established.

Bacteria↗
PubMed2003

Monitoring and characterisation of bacteria in corroding district heating systems using fluorescence in situ hybridisation and microautoradiography.

Presence of biofilm and biocorrosion has been observed in Danish district heating (DH) systems despite very good water quality that was expected to prevent significant microbial growth. The microbiological water quality was investigated in order to identify the dominating bacterial groups on surfaces with corrosion problems. Water samples from 29 DH systems were investigated for the total number of bacteria and presence of sulphate reducing bacteria (SRBs). SRBs were found to be present in more than 80% of the DH systems. The microbial population in samples from 2 DH system (biofilm from a test coupon and an in situ sample from a heat exchanger) was investigated with fluorescence in situ hybridisation, and the results showed significant differences in population composition. Betaproteobacteria was the dominant population in both samples. SRBs were present in both samples but were most numerous in the biofilm from the test coupon. Examination of functional groups based on uptake of radiolabelled acetate (microautoradiography) showed presence of both aerobic and anaerobic bacteria despite the fact that oxygen is not anticipated in DH systems.

Bacteria, Aerobic↗