Activated Carbon Facilitates Anaerobic Digestion of Furfural Wastewater: Effect of Direct Interspecies Electron Transfer

Abstract

Anaerobic digestion of furfural wastewater suffers from toxicity to microbes, which reduces its performance. The toxic effects may be eliminated by a sustainable way of conductive material supplementation. In this study, the effect on anaerobic digestion of furfural (0.5–4 g/L) was investigated by adding 0–40 g/L granular activated carbon (GAC) in batch tests. The innovation of this current study is to explore the potential direct interspecies electron transfer (DIET) for the first time in furfural degradation as the sole substrate in anaerobic digestion. The results demonstrated that when furfural was the sole substrate, in the presence of GAC, the peak methane production rate was increased by 46.0%, while the specific methane yield was improved by 24.7%, compared with the control. Additionally, the electroactive Geobacter sulfurreducens abundance in biofilms attached to the surface of GAC was 19.0 folds higher than that in the control. The abundances of the related genes of methane metabolism and furfural degradation in biofilms were 1.1 and 5.8 folds higher than the control by metagenomic analysis, respectively. These lines of evidence suggested that the pathway of furfural metabolism to methane among Moorella species, G. sulfurreducens, and Methanothrix species based on DIET was likely established.