Enhanced degradation of phenolic compounds in coal gasification wastewater by activated carbon-Fe3O4 nanoparticles coupled with anaerobic co-metabolism

Abstract

The aim of our research was to investigate the enhanced anaerobic degradation process of coal gasification wastewater (CGW) by conductive material activated carbon and Fe3O4 nanoparticles (Fe3O4 NPs) with the assistance of co-substrate. The optimal ratio of activated carbon to Fe3O4 NPs (3:1) and the optimal addition of co-substrate (glucose concentration =1500 mg/L) were explored through batch tests. During the long-run reactor experiments, 1500 mg/L glucose was mixed into the influent, and activated carbon-Fe3O4 NPs in a ratio of 3:1 were mixed into the anaerobic sludge. The concentration of total phenols in the effluent was kept around 50 mg/L, with a removal rate of 96% and an increase in methane production to 226 mL/day in the experimental reactor. Compared with the control reactor, the methane yield was increased by 64.6%. Toxicity analysis indicated that the toxicity of CGW can be greatly alleviated by conductive material activated carbon and Fe3O4 NPs coupled with anaerobic co-digestion conditions. Microbial community analysis demonstrated that direct interspecies electron transfer (DIET) may have occurred between exoelectrogens (Clostridium, Anaerolinea, Mesotoga, Synergistia) and methanogenic endoelectrogens (Methanobacterium, Methanothrix) for syntrophic metabolism through activated carbon-Fe3O4 nanoparticles coupled with anaerobic co-metabolism.