Biocorrosion, Biodeterioration, and Biofouling in Civil Engineering

Abstract

Prevention of biodeterioration, biocorrosion, and biofouling of the construction materials is a task of Construction Biotechnology. Almost all construction materials can deteriorate due to microbial oxidation/reduction of C-, Fe-, S-, and N-containing compounds, hydrolysis of cellulose and hemicellulose of timber, production of organic and inorganic acids or alkali, and generation of oxygen radicals. Wood and paper can be easily biodegraded by the microorganisms under humid conditions. Objects of art, sculptures, and historical buildings are also deteriorated by microorganisms in humid and polluted atmosphere. Such organic acids as formic, acetic, propionic, butyric, lactic, gluconic, and other acids produced by bacteria during fermentation and fungi during oxidation, as well as sulfuric and nitric acids produced by bacterial oxidation are active corrosive agents. Microorganisms can induce corrosion by stimulation of the anodic reaction; formation of acids, by stimulation of the cathodic reaction, microbial production of H₂S; by the biodegradation of protective films, and by increase of conductivity of the liquid environment. All microbially caused problems can be controlled by: (1) biocides; (2) maintenance of the conditions unfavorable for microbial growth and activity, for example, low humidity and water content, and absence of electron donors and acceptors; (3) conventional corrosion control methods. Chemical biocides and preservatives are widely used in all industries. Environmentally friendly biotechnological preservatives for timber are developing. Negative role of microorganisms in constructions is also formation of bioaerosol, which is a collection of airborne biological particles such as viruses, cells of bacteria, spores of fungi, cells of algae, with the size ranged from 0.1 to 30 μm. To prevent production of aerosols the selection of proper materials, humidity, ventilation, and air conditioning conditions must be made, and in the cases when infectious agent is present in air, disinfection of this air by UV light or purification of air by adsorption filtration through activated carbon of fine fibers must be made, and a source of pathogens has to be removed or eliminated.