title: Corrosion by bacteria of concrete in sewerage systems and inhibitory effects of formates on their growth.
abstract: Not only sulfur-oxidizing bacteria but also an acidophilic iron-oxidizing bacterium (or bacteria) were found in the corroded concrete from several sewerage systems in Japan. The surface pH of concrete test piece exposed to an atmosphere containing hydrogen sulfide of the concentrations more than 600 ppm in the systems was usually below 2 after a month. This was attributable to ability of the sulfur-oxidizing bacteria to grow in the thin water layer which contained hydrogen sulfide and covered the piece even when the surface pH of concrete was 12-13. When the sulfuroxidizing bacteria grew in the surface of concrete and produced sulfuric acid, the pH of the inner parts of concrete was lowered where the bacteria were hardly found. Probably, sulfuric acid formed by the bacteria in the surface parts penetrated into the inner parts. The different species of sulfur-oxidizing bacteria were found in different sewerage systems. The growth of the sulfur-oxidizing and acidophilic iron-oxidizing bacteria was completely inhibited by formates, especially by calcium formate of concentrations more than 50 mM. Calcium formate can protect concrete in sewerage systems from bacterial corrosion.
authors.affiliation: Department of Materials and Applied Chemistry, College of Sciences and Technology, Nihon University, Kanda-Surugadai, Tokyo, Japan. yamanaka@chem.cst.nihon-u.ac.jp
authors.forename: Tateo
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Iwao
authors.initials: I
authors.lastname: Aso
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Togashi
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanigawa
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shoji
authors.forename: Tsugumichi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Naoki
authors.initials: N
authors.lastname: Watanabe
authors.forename: Kazuo
authors.initials: K
authors.lastname: Maki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D001419:Bacteria; D002118:Calcium / Q000737:chemistry; D003252:Construction Materials; D003343:Corrosion; D005561:Formates / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D011157:Population Dynamics; D012722:Sewage
chemical_list: D005561:Formates; D012722:Sewage; C030544:formic acid; D002118:Calcium