The use of magnesium peroxide for the inhibition of sulfate-reducing bacteria under anoxic conditions

Sulfate-reducing bacteria (SRB), which cause microbiologically influenced material corrosion under anoxic conditions, form one of the major groups of microorganisms responsible for the generation of hydrogen sulfide. In this study, which is aimed at reducing the presence of SRB, a novel alternative approach involving the addition of magnesium peroxide (MgO₂) compounds involving the use of reagent-grade MgO₂ and a commercial product (ORC™) was evaluated as a means of inhibiting SRB in laboratory batch columns. Different concentrations of MgO₂ were added in the columns when black sulfide sediment had appeared in the columns. The experimental results showed that MgO₂ is able to inhibit biogenic sulfide. The number of SRB, the sulfide concentration and the sulfate reducing rate (SRR) were decreased. ORC™ as an additive was able to decrease more effectively the concentration of sulfide in water and the SRB-control effect was maintained over a longer time period when ORC™ was used. The level of oxidation–reduction potential (ORP), which has a linear relationship to the sulfide/sulfate ratio, is a good indicator of SRB activity. As determined by fluorescence in-situ hybridization (FISH), most SRB growth was inhibited under increasing amounts of added MgO₂. The concentration of sulfide reflected the abundance of the SRB. Utilization of organic matter greater than the theoretical SRB utilization rate indicated that facultative heterotrophs became dominant after MgO₂ was added. The results of this study could supply the useful information for further study on evaluating the solution to biocorrosion problems in practical situations.