Enhancing High Solid Anaerobic Digestion of Kitchen Waste with Red Mud Addition: Performance and Microbial Community

High solid anaerobic digestion (HSAD) can not only produce methane-rich biogas for energy recovery but also treat kitchen waste (KW). However, HSAD of kitchen waste was of poor methane production due to its high organic compounds. Red mud (RM) is an alkaline conductive material that holds the potential to alleviate acidification and mediate the direct interspecies electron transfer (DIET) process when added to AD rectors. In this study, effects of different RM dosage addition (10, 30, 50, 70, 90 g/L) on high solid kitchen waste anaerobic digestion (KWAD) was evaluated. The results showed that the cumulative biogas production and methane production of reactor with 50 g/L RM addition reached 362.36 ± 7.42 mL/g VS and 75.31 ± 2.41 mL/g VS, which were 45.98% and 210.04% higher compared with the control group, respectively. The abundance of bacteria and the methanogens ( Synergistota , Methanosaeta ) which potentially participated in DIET were enriched. In addition, RM addition might be beneficial to establish the syntrophic metabolic relationship between bacteria ( Synergistota , Syntrophomonadaceae ) and methanogens ( Methanosaeta , Methanospirillum ). This study provided initial scientific evidence to evaluate the role of RM in high solid KWAD system, with important implications for enhancing HSAD at economic cost.