Promoting direct interspecies electron transfer and acetoclastic methanogenesis for enhancing anaerobic digestion of butanol octanol wastewater by coupling granular activated carbon and exogenous hydrogen.

Abstract Butanol octanol wastewater (BOW) generated from syngas conversion of coal contained abundant toxic organic pollutants. Anaerobic digestion is a promising technology for BOW, but abundant toxic substances would inhibit the activity of anaerobic microorganisms. Granular activated carbon (GAC) and exogenous hydrogen (EH2) were employed to enhance anaerobic digestion of BOW. The results indicated that methane production increased to 289.55 ± 17.43 mL CH4/g COD in EH2/GAC group, which was 1.07, 2.04, and 1.98 times of that in GAC, EH2, and control groups, respectively. In EH2/GAC group. The relative abundance of Geobacter and Methanosaeta increased rapidly to 25.36% and 52.81%, respectively, and the relative abundance of Clostridium was 9.78%. The underlying mechanism might be that GAC promoted the enrichment of Geobacter, and EH2 changed metabolic mechanism of Clostridium, stimulating the enrichment of Methanosaeta. Direct interspecies electron transfer was promoted by EH2/GAC, thus improving the methane production rate of BOW.