Search

The role of red mud in the improvement of methanogenesis during sludge anaerobic digestion was innovatively investigated in this study. The results demonstrated that the addition of 20 g/L red mud resulted in a 35.5% increase in methane accumulation. Red mud effectively promoted the hydrolysis-acidification of organic compounds in the sludge, which resulted in the increase of protein, polysaccharide, and VFAs by 5.1–94.5%. The activities of key enzymes were improved by 41.4–257.3%. Electrochemical measurements presented direct evidence that the electrical conductivity was significantly improved with red mud. More conductive magnetite was formed during the secondary mineralization after Fe(III) reduction by Fe (III)-reducing genes such as Clostridiaceae and Ruminococcaceae . The higher conductivity enhanced the electron transfer between the syntrophic bacteria ( Geobacteraceae ) and methanogens ( Methanosaeta and Methanosarcina ), and then improved the methanogenesis. This research provides a novel perspective on the synergism between sludge and red mud for methane production. [ABSTRACT FROM AUTHOR]