Sulphate-reducing bacteria associated with biocorrosion: a review

Abstract

Biocorrosion means any process of corrosion in wich microorganisms are somehow involved. As far as the petroleum industry is concerned, the anaerobic type is the more important, with Sulphate-Reducing Bacteria (SRB) accouting for half of the described processes. SRB are obligate anaerobs that use sulphur, sulphate or other oxidized sulphur compounds as oxidizing agents when decomposing organic material. A typical product of SRB metabolism, hydrogen sulphide -H2S-, is extremely toxic. In the present work we review the literature on mechanisms underlying biocorrosive process in wich SRB are involved and summarize some of the ultrastructural and eletrochemical work developed using SRB obtained from water injection flow in wells located on PETROBRAS offshore marine plataforms, sampled directly in the field over metallic probes, or cultured under laboratory conditions. Biofilms develop when SRB adhere to inert surfaces. A high diversity of morphological types is found inside these biofilms. Their extracellular matrix is highly hydrated and mainly anionic, as shown by its avid reaction with cationic compounds like ruthenium red. We have noted that variations in iron contet lead to interesting changes in the ultrastructure of the bacterial cell coat and also in the rate of corrosion induced in metallic test cupons. Since routine methods to prevent and treat SRB contamination and biodeterioration involve the use of biocides that are toxic and always have some environmental impact, an accurate diagnosis of biocorrosion is always required prior to a treatment decision. We developed a method that detects and semi-quantifies the presence of living or dead SRB by using free silver potentials as an indicator of corrosive action by SRB-associated sulphides. We found a correlation between sulphide levels (determined either by spectrophotometry, or using a silver electrode -E(Ag)- that measured changes in free potentials induced by the presence of exogeneously added sulphide) and SRB concentration (enumerated by a culturing method). E (Ag) was characterized under a variety of conditions andwas found to be relatively immune to possible interference resulting from aeration of media or from the psence of iron corrosion products. The method offers a simple, rapid, and effective means of diagnosing biocorrosive processes prior to their control

Thermotoga hypogea sp. nov., a Xylanolytic, Thermophilic Bacterium from an Oil-Producing Well

“…Studies of these organisms may be useful in the development of microbeenhanced oil recovery processes (4, 29). In addition, members of the order Thermotogales and Themzoanaerobacter species, which have the ability to reduce thiosulfate during growth on carbohydrates (14, 36), may be involved in biocorrosion of oil field facilities (8,10,12,16,27). Strain SEBR 7054T is an anaerobic, rod-shaped thermophile with an outer sheathlike structure (toga) similar to that described for the members of the genera Thermosipho, Geotoga, Petrotoga, and Thermotoga.…”

IRON PIPE corrosion IN DISTRIBUTION SYSTEMS

“…Microorganisms are present in many distribution systems (Holden et al, 1995;LeChevallier et al, 1993;De Araujo-Jorge et al, 1992;Emde et al, 1992;Victoreen, 1984;Allen et al, 1980;Lee et al, 1980;Tuovinen et al, 1980;O'Conner et al, 1975;Larson, 1939), and they can influence iron corrosion in a number of ways. Bacteria have been found in iron tubercles Allen et al, 1980;Tuovinen et al, 1980;Victoreen, 1974).…”

Radiorespirometric assays for the detection of biogenic sulfides from sulfate-reducing bacteria

“…The resulting environment favours bacterial growth, offering anaerobic conditions with sulfate and nutrients. In this particular case, during the production and storage of petroleum, there are many points at which biocorrosion is a problem (Ara ujo-Jorge et al 1992). In the case of growth of a consortium of microbes, SRB adhere to inert surfaces with subsequent development of biofilms, which mediate the interaction between metal surfaces and the environment (Videla 1989).…”