The effects of Tetrakis-hydroxymethyl phosphonium sulfate (THPS), nitrite and sodium chloride on methanogenesis and corrosion rates by methanogen populations of corroded pipelines

The effects of some biocides on methanogens associated with pipeline corrosions were investigated. The crude oil transporting pipeline showed higher methane production (60%) and corrosion rates (42%) than the water transporting pipeline. Higher concentrations of biocide (0.7% Tetrakis-hydroxymethyl phosphonium sulfate) and 40 mM nitrite were required for both pipelines to sufficiently inhibit methanogenesis and corrosion rates. A sudden increase in corrosion rate happened only in samples that produced higher than 1.5 mmole of methane. Pyrosequencing surveys shows dominance of acetotrophic, hydrogenotrophic and methylotrophic methanogens in the samples. The methane productions and corrosion rates were strongly correlated under all the conditions.