Biofouling

This book covers the field of biofouling in its widest sense by bringing together a suite of reviews that deal with basic and applied research, the industry of paints and coatings and environmental law and governance. It devotes serious attention to the subject of corrosion of metallic surfaces caused by macroand micro-organisms, in particular by microbial fouling. Adhesion of bacteria and microalgae is mediated by secretion of glue-like substance of extracellular polymers (EPS). Microbial induced corrosion (MIC) occurs by cathodic and anodic depolarisation and production of corrosive metabolites such as organic acids and exopolymers. Biofouling causes severe operational and maintenance problems to the cooling water towers of powers plants, which are colonised by bacteria. The resulting slime layer reduces heat exchange efficiency and corrosion increases under the anaerobic slime layer. Chemical controls by injection of biocides and application of corrosion inhibitors are the preferred biofouling control technology of industrial water treatment. Antifouling paints containing active biocides are used to avoid the settlement by fouling organisms and their growth on ships, aquaculture equipment and other structures in marine environment. Techniques are employed to prevent the biocides release into the surrounding waters to minimise the impact on the environment and damaging its quality. The physical properties of the immersed structure surfaces such as roughness, texture, chemical composition, wettability, interfacial alkalinity affect the settlement of a variety of marine organisms during biofouling community development; these parameters also determine the type of corrosion and its extent. The complex environmental, physical, chemical and biological interaction during the initiation of corrosion and the damage to the fixed structures, e.g. oil and gas platforms, and to the mobile structures, e.g. ships. The control of marine fouling is realised, essentially, by application of paints and coatings containing special biocides such as copper compounds which liberate cupric ions when they come into contact with seawater. Antifouling paints and coatings are described in chapters 13, 16, 25 and 27. They introduce environmentally benign coatings copying natural control to fouling based on defense mechanisms against biofouling: behavioural, mechanical, physical and chemical; this natural control is diverse, complex and antifunctional as detailed in chapter 8. The surface of submerged equipment, such as ships hulls, water intake pipes, heat exchangers, reverse osmosis membranes, sensors, food preparation, teeth, arteries and implants in humans deteriorate, degrade and corrode by the aggressive attack of attached biofouling. Existing commercial solutions to biofouling require a compromise between fouling management, corrosion and environmental conservation. As corrosion professionals with activities and publications on marine and fluvial corrosion of structures: fixed (ports, shipyards, oil and gas platforms and mobile (merchant ships, naval vessels); we enjoyed reading chapter 15 about the consequences of fouling on shipping. It gives a brief history of ships biofouling, from ancient times to the modern era, including aspects of corrosion and the drag effect on the ship velocity and its consumption of fuel. The biofilm modifies the interface: steel hullseawater influencing the electrochemistry at the metal surface. This chapter concludes that biofilms enhance corrosion but good quality coatings and electrochemical system con prevent, or at least retard corrosion. Chapter 23, on biofouling and climate change, arouses our interest too. Increase of greenhouse gases, mainly CO2, and the rise of global surface temperature promotes CO2 dissolution into the sea, slightly elevating its acidity and, consequently, altering the life of the fouling organisms. Recently the Institute of Materials, Minerals and Mining (IOM3), London, published a special issue of its journal: Corrosion Engineering, Science and Technology [Vol. 45, (1), 2010], which brings together papers examining climate change induced corrosion. This is a book a with multiple authors: 42, coming from a broad spectrum of universities, R&D institutes, marine, biology and ecology laboratories but, unfortunately only two or three industrial producers of antifouling paints and coatings participate. Nevertheless it offers the authors scientific knowledge and practical experience, with significant, different approaches and views, which certainly enrich this volume. With so many authors, it suffers from minor repetitions which, on the other hand, are difficult to avoid in such a large, profuse book with 27 chapters and 42 authors! However, a professional editor should have devoted more effort and time to eliminate theses slips. The economic importance of the antibiofouling activities, in particular in the shipping industry, is demonstrated by the involvement of national and international organisations, which regulate the industry, such as: International Maritime Organization (IMO), Integrated Pollution and Control (European Commission); International Antifouling System (IAFS); International Chamber of Shipping; International Convention for the Control and Management of Ships Ballast Water and Sediments; International Council for the Exploration of the Sea and more.... All these agencies cooperate between them and supply information to the public.