Bio-competitive exclusion of sulfate-reducing bacteria and its anticorrosion property

The bio-competitive exclusion (BCX) method is a practical, environment-friendly, and low-cost method of controlling sulfate-reducing bacteria (SRB) and focuses on research and preliminary applications. In this study, a nitrate-reducing bacteria (NRB) were screened and selected from oil-producing water and identified as heterotrophic Pseudomonas sp. through 16S rDNA. The NRB activation and the SRB inhibition systems were studied via the addition of the bio-activators NO3− and NO2−. In addition, the synergistic inhibitory effect of NRB and molybdate on SRB was studied. Results showed that the inhibitory effect of NO2− was better than that of NO3−. At NO3− to NO2− ratio of 1:4, the inhibitory effect was optimum. The addition of 5% activated NRB and a small amount of molybdic acid salt played a synergistic effect. The optimal inhibition system contained the following: 5% NRB, NO3−/NO2− of 1:4, and the amount of molybdate was 1/5 that of NO3−. In this inhibition system, S2− can maintain an extremely low content, and SRB activity was well inhibited. Static corrosion simulation experiments showed that SRB was the main cause of corrosion. The effects of biological inhibitors, fungicides, and corrosion inhibitors on the corrosion inhibition were investigated. Results showed that the corrosion rate of biological inhibitors was the lowest, and the best effect of corrosion inhibition was achieved. The surface morphology of the corroded steel sheet was analyzed via scanning electron microscope. In addition, the surface corrosion of the steel sheet was low, and no pitting was observed.