Effect of biocides and corrosion inhibitors on SRB-mediated MIC under flow conditions

摘要

Biocides and corrosion inhibitors can decrease corrosion in stagnant and flowing systems, like storage tanks and pipelines. We have used 1 ml syringe columns packed with 60 carbon steel beads (55 mg each), which were continuously injected with the effluent of an SRB continuous culture chemostat, to monitor corrosion under flow conditions. A constant flow rate of 0.5 ml/hr was maintained throughout. General corrosion rates (CRs) were determined after 45 days of flow by measuring the weight loss of acid-treated beads. Medium entering the chemostat contained sulfate (10 mM) and formate (20 mM) for the growth of SRB. Effluent of the chemostat with 5 mM sulfate, 5 mM sulfide and high numbers of SRB was then continuously injected into the syringe columns. CRs of beads in these columns were 0.1 mm/yr. Periodic biocide treatment (2 h of 300 ppm every 5 days at the same flow rate) decreased CRs on average by 60% for two of five biocides tested, indicating control of corrosion in the system. In contrast, a single exposure of the carbon steel beads to a water-dissolved corrosion inhibitor at the start of the experiment decreased CR by 50%, whereas single exposure to two diesel-dissolved corrosion inhibitors decreased CR by 90-98%.