Mikrobielle Werkstoffzerstörung — Biofilm und Biofouling. Simulation mikrobiell beeinflußter Metallkorrosion (MIC) zur Prüfung von Gegenmaßnahmen

Simulation of metal-MIC for evaluation of countermeasures Microbiologically influenced corrosion (MIC) of metals is generally associated with the existence of a biofilm. To simulate and monitor these processes a mobile test apparatus was developed offering the possibility to simultaneously test the resistance of different metallic materials. Up to now biofilm development on metal surfaces and corrosion resistance of metal samples (St 37 and 1.4301-steel) were examined. The strongest attack on St 37 steel was obtained with a biogenic sulfide film at the metal surface as a result of the metabolism of sulfate reducing bacteria being exposed to oxygen. A continuous change between anaerobic and aerobic conditions in the presence of sulfate reducing bacteria resulted in a maximal penetration of about 1 mm/year in the case of St 37-steel. Under strict anaerobic conditions penetration amounted to 0.7 mm/year. Furthermore, a microcalorimetric test was developed to determine microbial activity of biofilm samples. The test offers a certain advantage for measuring the efficiency of biocides. It could be demonstrated that the concentration of a commercial biocide had to be increased considerably to be effective.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Umweltrechtliche Belange

Microbial deterioration of materials – case histories and countermeasures: Legal aspects of environmental protection Biofouling is a natural process. Usually, it does not cause too much harm if taken care of properly. If biofouling is fought by special means, problems may arise. The waste water does not meet the due standards. Sometimes the recipe of the treatment agent is not known. If the treatment causes more problems than it can solve help is needed quickly. Yet, it is advisable to keep one's mind clear. Wrong help can become very expensive. In addition, legal punishment will follow, if environmental legislation is hurt. Damages of the environment will be payed by an insurance company only, if the risk is covered by the insurance contract in advance. The best way to be sure is to have a good lawyer, a good expert in environmental techniques and environmental legislation, a good insurance, and to anticipate possible risks.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Anwendung von Mikrobiziden. Mikrobizid-Wirkungsmechanismen

Microbial deterioration of materials – case histories and countermeasures: Application of microbicides – Mechanisms of functioning of microbicides Microbicides are defined as a subgroup of the biocides. Such microbicides are discussed here which are appropriate for the protection of materials, additionally active ingredients for disinfectants and agents able to prevent disturbances and damage caused in industrial processes by formation of algae and slime. The effective use of microbicides presupposes knowledge of the materials and production processes to be protected, of the microbe species responsible for the biodeterioration and of the properties and mechanisms of action of the active agents conditional on their structure. This knowledge enables one to select an appropriate microbicide for the solution to the problem. Different modes of action are described basicly and adjuncted to certain substance classes. It is differentiated between membrane-active and electrophilically active agents and those which are able to form chelates. The differences in mechanisms of action result in different consequences for the application of microbicides.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen für Kunst- und Naturstoffe: Mikrobielle Zerstörung von Kunststoffen

Microbial deterioration of materials – case histories and countermeasures for plastics and organic and natural materials: Microbial deterioration of plastics Large-scale production of synthetic plastics began in the thirties. The versatility of the new materials was enhanced by new processing technologies and above all by designing special formulations tailored to the different fields of applications. Their increasing universal application was, however, also accompanied by growing records of documented microbial attack. The mechanisms of attack have largely been identified. Damage is commonly caused by surface growth, discolourations and changes of mechanical and electrical properties. National and international test standards have been developed to predict the service life of certain plastics or to evaluate the protection afforded by certain biocides. Several standard methods of test are presented and the criteria for evaluation are critically examined. Finally, the activities of the Plastics Project Group are represented, wich has carried out several international co-operative tests to evaluate the reproducibility of the results of different test methods and has worked out recommendations and improvements.     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen: Mikrobielle Vielfalt auf Werkstoffen und Besiedelungswege

Microbial deterioration of materials – simulation, case histories, and countermeasures: Microbial variety on materials and means of contamination Different types and varying mixtures of microorganisms (bacteria, fungi, algae) were normally found living at the surfaces of different materials and several centimeters inside of porous locations. The inoculation of freshly exposed, as well as of already contaminated, surfaces occurs by immission (air, rain, dust), by excrements (birds, insects etc.), or by direct contact, e.g., wood boring insects, or from running water. An air transport of fungal spores, e.g., has been shown to occur over hundreds of kilometers. Growth and multiplication of cell numbers of these “settlers” depends on the presence of a proper mixture of organic and inorganic nutrients, especially of a sufficient supply of water. This indicates that not all microorganisms will multiply in any case nor corrode all the materials they have reached. Some of them will die and may serve as nutrients, others will grow without attacking the materials but may support growth of corroding types. A substantial attack of materials by microorganisms is normally brought on only by a greater number of potent and active cells.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Allgemeine Schutzmaßnahmen vor biogener Materialzerstörung

Microbial deterioration of materials – case histories and countermeasures: General measures for protection against biogenic destruction of materials Many materials are adversely affected or even destroyed by microorganisms. In the cases where the causes of biogenic damage are known, specific protective measures can be taken. Depending on the material in question, these measures can be of a constructional, physical or chemical nature, and all three procedures are frequently used in combination. Constructional measures are to be found in the “buildings” sector. Examples to be mentioned are water being led off at windows and buildings being ventilated in order to prevent mould invasion in particular. Treating surfaces by applying adhesive coatings or water-repellent products can prevent attack by microorganisms on e.g. wood and metals. Physical measures are also used in protecting buildings. In addition to insulating the building, which then has few bridges of heat, the sorption behaviour of the surfaces and the heat transfer coefficients on the surfaces also influence the growth conditions for microorganisms. Materials with a high sorption capacity have particularly adverse effects on poorly insulated buildings. As chemical protective measures, use is made of preservatives and products for microbistatic treatment and also impregnating agents. These measures are applied in the paint, paper, and wood industries, among others. In addition, the choice of raw materials and the use of “rot-proof” materials in textiles and plastics can reduce microorganism-induced biodegradability and, thus, prolong the life. Not least, on the majority of production sites good production hygiene is urgently necessary as a concomitant measure.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen für Kunst- und Naturstoffe: Beschichtungssysteme

Microbial deterioration of materials – case histories and countermeasures for plastics and natural materials: Coating systems As all other organic materials, coating films as well (e.g. paints, varnishes, plasters) are exposed to corrosion phenomenons as a result of environmental conditions. Thus, high moisture and temperature are promoting conditions for microbial growth on diverse coating materials: Microbial colonization is favoured by structural engineering faults. Microorganisms and their metabolites do not just lead to discolourisation but also to the disfigurement and finally the destruction of the structural integrity of the film. The protection of exposed and endangered coating systems from potentially harming microbial colonization is achieved by the use of fungicidal and algicidal film microbiocides well adapted to the type of coating and the application area (indoor or outdoor use). Compatibility with the coating, comprehensive efficacy, stability as well as low toxicity are main criteria for their application. In respect to efficacy, both the type and the amount of microbiocide are determined by biovalidation through testing either in the laboratory by contaminating the test panels with fungal spores and algae or in long-term field studies. In case of laboratory tests, to obtain reliable results practical conditions are created by artificial weathering such as watering and UV irradiation.     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen: Metallische Werkstoffe – Überblick

Microbial deterioration of materials – simulation, case histories and countermeasures: Metallic materials Overview Microbially induced deterioration of construction metals has been encountered in many industrial processes and installations. Corrosion failures of technical equipment often occur under operational conditions which do not appear to be conducive to microbial growth. Although, many different types of microorganisms can be implicated in corrosion processes, most widespread and distinctive is the corrosion resulting from the activities of the sulfate-reducing bacteria, further sulfur-oxidizing and various acid-producing bacteria. This paper deals mainly with case histories which occurred in energy producing installations and industrial waste-water treatment plants. An attempt was made to describe in detail the investigations which had hen performed in order to elucidate the cause of corrosion failures. Relatively simple diagnostic procedures can be helpful in explaining such cases; the condition is that microbial activity is included in considerations concerning potential contributors to the failure mechanism. Discussion of remedial measures includes methods based on the use of biocides as well as alternative procedures.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen für Kunst- und Naturstoffe. Kohlenwasserstoffe

Microbial deterioration of materials – case histories and countermeasures for plastics and natural materials: Hydrocarbons A wide range of bacteria, yeasts and filamentous fungi utilize hydrocarbons as their sole energy and carbon sources. Microbial degradation of hydrocarbons has economic implications when spoilage of crude oils and petroleum products such as fuels, hydraulic oils, lubricating oils, and cutting oil emulsions will occur. As a consequence of microbial infection the oil product changes chemically and functionally and some components may disappear completely. Metabolic products may cause severe corrosion or may be used as substrates by other microorganisms, e.g. sulfate reducers, which for this part will cause corrosion. In consequence of biomass production screens and filters may be blocked and plugging of pores and pipeline-systems may occur. As spoilage can only, occur in the presence of free water, good housekeeping is a prerequisite to prevent microbial hydrocarbon degradation. In cases free water cannot be excluded or removed completely, biocides can he added. The growth of anaerobic bacteria (sulfate reducers) is inhibited by introducing oxygen into the system. Coatings can be used to protect metal surfaces from corrosion.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen für Kunst- und Naturstoffe. Biotransformation und Kompostierbarkeit von Folien

Microbial deterioration of materials – case histories and countermeasures for plastics and natural materials: Biotransformation and cornposting of foils     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen: Untersuchung der Beständigkeit von keramischen Werkstoffen

Microbial deterioration of materials – simulation, case histories and countermeasures: Testing of the resistance of ceramic materials Testing of microbiologically influenced corrosion of ceramic materials by biogenic sulphuric and nitric acid corrosion is well described and applied for constantly moist buildings like sewage pipelines and cooling towers. The complex situation on historical buildings of natural sandstones has not yet been investigated in the laboratory. A double-chamber cabinet and a test system for the simulation of chemically (gaseous pollutants), combined chemically and microbiologically (gaseous pollutants plus nitrifying bacteria) and solely micro biologically (nitrifying bacteria) influenced corrosion of 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 (1,065 μg/m³ sulphur dioxide, 850 μg/m³ nitric oxide, and about 450 μg/m³ nitrogen dioxide): in the simulated smog atmosphere. The mean metabolic activities of ammonia oxidizers were 11 times and those of nitrite oxidizers 30 times higher than mean values of samples from historical buildings. The microbiologically, influenced nitric acid corrosion alone was 8 times stronger than the chemically influenced corrosion by the simulated smog atmosphere. If sulphur dioxide was added, the microbiologically produced nitrite was removed by chemodenitrification. Thus, the combined attack of nitrifying bacteria and gaseous pollutants did not result in an increased corrosion, but the nitrifying biofilm promoted the formation of gypsum.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Anwendung von Mikrobiziden. para-Chlor-meta-Kresol (PCMK) – Ein klassisches Mikrobizid mit Zukuntt

Microbial deterioration of materials – case histories and countermeasures: Application of microbicides. Para-chloro-meta-cresol (PCMC)

1 Preventol®CMK.

– A classic microbicide with a future     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen für anorganische nichtmetallische Werkstoffe: Korrosion von Modellgläsern durch mikrobielle Stoffwechselprodukte

Microbial deterioration of materials – simulation, case histories and countermeasures for inorganic nonmetallic materials: Corrosion of glass samples by microbial metabolites The behaviour and the corrosive action of moulds was investigated on alkali silicate glass samples. The glasses were contaminated with selected fungi in liquid phase. The structure and extent of surface layers was measured by X-ray diffraction analysis, X-ray fluorescence, light microscopy and scanning electron microscopy (SEM/EDX, microprobe analysis). In the presence of moulds corrosion layers were formed at a 5 to 30 times bigger extent in comparison with the not contaminated samples. They correspond to leached hydrated layers.     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen für anorganische nichtmetallische Werkstoffe: Keramik

Microbial deterioration of materials – simulation, case histories and countermeasures for inorganic nonmetallic materials: ceramics During summer 1992 bacterial activity in ceramic caused disturbances in the production. Affected was the classical dinnerware production as well as sanitary ware and technical porcelain. For an undisturbed production constant parameters of all processing steps are required, especially constant parameters of batches. In the case of dinnerware and sanitaryware industries the hygienic quality of the process water could be detected as the source of microbiological activities. The pH-value and rheological properties of slurries and filtercakes and all dependent parameters were changed. This is demonstrated for several batches for the viscosity and pH value. In the case of technical porcelain recycled non fired material showed changes in pH-value and viscosity also, but the main damage was caused by gas evolution during storage of extruded rods of about 4 weeks. These preforms could not be further processed. The source for the microbiological impurity was an biodegradable oil, which was be used in shaping processes. The growth of the microbes occurred mainly under anaerobic conditions. As a first step aeration of the slurry was used to prevent the growth and, additionally, chemicals, as usually used in paper industry, were added to prevent the microbiological influence. During summer 1992 bacterial activity in ceramic caused disturbances in the production. Affected was the classical dinnerware production as well as sanitary ware and technical porcelain. For an undisturbed production constant parameters of all processing steps are required, especially constant parameters of batches. In the case of dinnerware and sanitaryware industries the hygienic quality of the process water could be detected as the source of microbiological activities. The pH-value and rheological properties of slurries and filtercakes and all dependent parameters were changed. This is demonstrated for several batches for the viscosity and pH value. In the case of technical porcelain recycled non fired material showed changes in pH-value and viscosity also, but the main damage was caused by gas evolution during storage of extruded rods of about 4 weeks. These preforms could not be further processed. The source for the microbiological impurity was an biodegradable oil, which was be used in shaping processes. The growth of the microbes occurred mainly under anaerobic conditions. As a first step aeration of the slurry was used to prevent the growth and, additionally, chemicals, as usually used in paper industry, were added to prevent the microbiological influence.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen für Kunst- und Naturstoffe: Papier und Füllstoffe

Microbial deterioration of materials – case histories and countermeasures for plastics and natural materials: Paper and additives During the production of paper and cardboard several aspects of microbiological attack may be observed. Paper raw materials, additives and the end product paper itself are attacked by microorganisms. The results are deterioriation and an alteration of the properties of valuable raw materials and a reduction of the paper quality. The greatest important economic loss arises from slime formation in the fiber preparation systems and in the paper machine itself. Biofilms are the reason for break-downs in production and affect the quality of the product. This article describes the sites where trouble during production occurs, the effects and value of the loss based on microbiological growth. Chemical and technical arrangements to reduce the origin of damages are discussed.     

Mikrobielle Werkstoffzerstörung – Simulation,Schadensfälle und Gegenmaßnahmen für anorganische nichtmetallische Werkstoffe: Biodeteriorationsprozesse an anorganischen Werkstoffen und mögliche Gegenmaßnahmen

Microbial deterioration of materials – simulation, case histories, and countermeasures for inorganic nonmetallic materials: Biodeterioration processes on inorganic materials and means of countermeasures Biodeterioration processes on inorganic materials such as natural stone, concrete, or glass can be subdivided into biogeochemical and biogeophysiological mechanisms according to their damage characteristics. In connection with the partial acidification and dissolving of components, biocorrosion as a result of biogenic release of inorganic and organic acids, as well as the biogenic oxidation of mineral forming cations, a certain weakening in the structure of the respective material can occur. The formation of biofilms on the surfaces of the inorganic materials impairs not only the aesthetical appearance of an object but also causes alterations in its humidity and temperature behaviour. In addition, due to the shrinking and swelling effects of biofilms, mechanical pressure to the mineral unit can occur (bioerosion, bioabrasion). Location and environmental factors which could lead to specific, biogenically determined weathering phenomena on these materials will be presented and elucidated. For controlling biodeterioration processes, the development and selection of environmentally-friendly, yet effective, inorganic and organic biocidal additives for stoneprotection agents as well as the use of gas (e.g. ethylene oxide) in their far-reaching significance for future material research will be presented here.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Anwendung von Mikrobiziden. Tebuconazole – ein neues Triazol-Fungizid für den Holzschutz

Microbial deterioration of materials – case histories and countermeasures: Application of microbicides. Tebuconazole

1 Preventol®A 8

– a new triazole-fungicide for wood protection