Intensifying anaerobic digestion of 5-hydroxymethylfurfural via granular activated carbon supplementation.

5-hydroxymethylfurfural (5-HMF) is typically found in hydrolysate produced by thermal pretreatment and wastewater streams, and its presence can significantly inhibit anaerobic digestion (AD) performance. This study comprehensively investigates the impact of adding 1–5 g/L granular activated carbon (GAC) on the AD of 0.5–4 g/L 5-HMF. The innovation of this study is to clarify the mechanism of direct interspecies electron transfer (DIET) in the AD system with 5-HMF as the sole source. Compared to the control group, adding 5 g/L GAC shows the most significant promotion effect, which increases the electron transfer activity of the sludge by 27.0%–75.0% and enhances the methane production peak rate by 27.5%–68.1%. GAC supplementation can rapidly reduce the concentration of 5-HMF by adsorption and alleviate its inhibition of microorganisms. SEM and microbial community analyses show that GAC enriches electroactive microbes and can promote AD by establishing the DIET pathway. [Display omitted] • First study to investigate the DIET potential in anaerobic digestion of 5-HMF. • GAC supplementation evidently intensified 5-HMF degradation and methane production. • The maximum methane yield by GAC addition was increased up to 36.7%. • Electron transfer activities of microbes increased by 27.0%–75.0% by GAC addition. • DIET connection was possibly established between exoelectrogens and methanogens. [ABSTRACT FROM AUTHOR]