METHANOGENIC AND CARBON SEQUESTRATION PROCESS FACILITATED BY GOETHITE AND HEMATITE IN THE PRESENCE OF DISSIMILATORY IRON-REDUCING BACTERIA

The conversion of waste organic matter to methane is an important bioenergy strategy, and a similar microbial metabolism of complex organic matter in anaerobic soils and sediments plays an important role in the global carbon cycle. There has been increasing concerns about renewable energy and carbon sequestration in recent years. This study demonstrated that methanogenic and carbon sequestration process can be facilitated by goethite and hematite in the presence of dissimilatory iron reducing bacteria. Methanogenic microbes were enriched from anaerobic sludge with acetate as a substrate in the absence of iron oxides (hematite or goethite). Batch tests showed that the supplementation with either of these iron oxides resulted in the acceleration of methanogenesis in terms of lag time and production rate. Meanwhile, the content of methane in the biogas was increased above 10% since that part of carbon dioxide produced was fixed in situ with the formation of siderite. Furthermore, the amount of soluble ferrous was promoted in the presence of dissimilatory iron reducing bacteria with the supplementation of either iron oxide. Methanogens can be syntrophic associated with goethite and hematite in the presence dissimilatory iron-reducing bacteria. Given the ubiquity of these minerals in nature, these results provided new evidence on the bio geochemistry of iron minerals and methanogenesis in the environment and can be used to develop efficient bioenergy processes.