Microbial Corrosion (EFC 15) PDF

Preface

This publication contains the papers from the third European Federation of Corrosion workshop on microbial corrosion organised by the Instituto Superior Tecnico, Lisbon, Portugal in collaboration with the EFC working party on microbial corrosion. The purpose of the workshop was to summarise the actual European experience in this field while also drawing on the recent experience from other countries. It represents the current concerns of the problems associated with corrosion induced by the activity of a wide range of microorganisms and, as such, encompasses a spectrum of interest from aerobic and anaerobic situations to the control and prevention of the problem or the assessment of new on-line monitoring techniques.

Microbially influenced corrosion (MIC) is by definition, corrosion associated with the action of microorganisms present in a system. MIC is, therefore, an interdisciplinary subject that embraces the fields of materials science, chemistry, microbiology and biochemistry. Since the first reports of MIC at the end of the 18th century in the UK much has heen done to understand the role of microorganisms in the corrosion of materials. However, the mechanisms by which microorganisms enhance corrosion of many materials still remains unclear.

This workshop was broadly divided into four main topic areas: (i)an interdisciplinary approach to MIC, (ii) mechanisms and general studies in the laboratory and in the field, (iii) case studies, and (iv) prevention and control. Experience with a variety of environments and materials is a feature of the reports in this volume. Thus, data are reported from potable water, river water, seawater and soils; the materials considered include stainless and carbon steels, copper, aluminium brass, fibre reinforced composites, etc.

The best example of the interdisciplinary approach which is required to understand the problem is given in the first section of the volume which is concerned with the MIC of copper in potable water systems. The model which has been developed to explain the mechanism by which copper is corroded includes the role of the biofilm and its permselectivity. During the workshop new theories were proposed for the anaerohic corrosion of iron and stainless steel by the sulphate-reducing bacteria involving the role of the thiosulphate ion.

It is also interesting to note that several new experimental techniques have been developed and used to characterise the nature of the biofilm which forms on the metal surface. Atomic Force microscopy and mass transport measurements using a spinning disc electrode have heen particularly successful in this respect.

New biosensors have been developed for the control and prevention of MIC and these should become commercially available in the near future. However, the use of biocide and cathodic protection still remain the standard approaches even if their overall efficiency may occasionally be questioned.

The case histories that are reported illustrate the wide and diverse range of materials that are susceptible to the problem of MIC including some of the newer materials such as plastic/metal composite matrices.

From the data presented during the workshop it was obvious that the mechanism of MIC remains a major concern and that there is still a considerable amount of Rand D to be undertaken. Nevertheless, this kind of workshop has continued to improve the general awareness of the subject to industrialists and to academia.

Improved communications between microbiologists, corrosion scientists and engineers will eventually result in a better comprehension of the mechanisms of microbial corrosion.

Edited by: A.D. Mercer