Enhancement of anaerobic digestion of rice straw by amino acid-derived ionic liquid

This study proposes a novel method to enhance methane production from anaerobic digestion using an amino acid-derived ionic liquid, glycine hydrochloride, ([Gly][Cl]), as an exogenous additive. After 40 days of digestion with 5% [Gly][Cl], the cumulative methane production was 115.56 mL/g VS, which was 73% higher than that of the control group (without additive). Specifically, the peak activities of cellulase, xylanase, and lignin peroxidase were significantly higher than those of the control group. The addition of [Gly][Cl] increased bacterial diversity and reduced archaeal diversity. Synergistota represented by Syner-01, Fibrobacterota represented by BBMC-4, Bacteroides, and unclassified_f__Lachnospiraceae significantly increased in relative abundance. It suggested that [Gly][Cl] stimulated the activities of protein-hydrolyzing and acid-producing bacteria. [Gly][Cl] also increased the abundance of methanogens and archaea, converting more lignocellulose to methane. Methanobacterium, that metabolizes H2 and CO2 to CH4, was more abundant. Therefore, [Gly][Cl] can improve methane yield as an anaerobic digestion additive.

Automated summary

This study proposes a novel method of enhancing methane production from anaerobic digestion by using an amino acid-derived ionic liquid, glycine hydrochloride ([Gly][Cl]), as an exogenous additive. The study found that after 40 days of digestion with 5% [Gly][Cl], the cumulative methane production was 73% higher than the control group. The addition of [Gly][Cl] increased bacterial diversity, decreased archaeal diversity, and stimulated the activities of protein-hydrolyzing and acid-producing bacteria.