Performance, mechanism and stability of nitrogen-doped sewage sludge based activated carbon supported magnetite in anaerobic degradation of coal gasification wastewater

In current study, the UASB reactor was enhanced by nitrogen-doped sewage sludge based activated carbon supported Fe3O4 (Fe3O4/N-SBAC) for coal gasification wastewater treatment. The results showed that COD removal efficiency was increased to 64.4% with Fe3O4/N-SBAC assistance and the corresponding methane production rate achieved up to 1093.6 mL/d. Fe3O4/N-SBAC promoted microbial growth and enzymatic activity, leading to high extracellular polymeric substances and coenzyme F420 concentrations. Fe3O4/N-SBAC also facilitated the sludge granulation process with high particle size, substantial interspecific signal molecules and low diffusible signal factor. Microbial community analysis revealed that Fe3O4/N-SBAC might support direct interspecies electron transfer process, in which the enriched Geobacter was likely to communicate with Methanothrix via electrical connection, improving anaerobic degradation of coal gasification wastewater. Total phenols shock and pH impact revealed that reactor stability was enhanced in the Fe3O4/N-SBAC-supplemented system. [Display omitted] •Fe3O4/N-SBAC improved pollutant removal and methane production rate.•Fe3O4/N-SBAC facilitated microbial accumulation and sludge granulation.•Enriched Geobacter might perform DIET with Methanothrix.•Reactor with Fe3O4/N-SBAC assistance could resist Tph shock and acidic impacts.