Direct interspecies electron transfer stimulated by coupling of modified anaerobic granular sludge with microbial electrolysis cell for biogas production enhancement

The magnetite nanoparticle-anaerobic granular sludge complex (Fe-AnGS) was formed by a biologically induced mineralization method, then applied in microbial electrolysis cells (MEC) to enhance the direct interspecies electron transfer (DIET) pathway via selective enriched electrogenic microorganisms for biogas production. Results showed with the highest Fe loading amount of 325.03 +/- 8.40 mg/gVS, the magnetization and conductivity of Fe-AnGS were improved by 30.94 % and 29.16 %, respectively. The MEC with Fe-AnGS enriched the specific electrogenic microorganisms in the anode and cathode chambers. Simultaneously, genes coding for carbon dioxide reduction [M00567] increased by 29.40-43.54 % and 34.29-43.43 %, respectively. Inoculation of Fe-AnGS in MEC with glucose as substrate enhanced the experimental methane production of the cathode chambers (EMPC), and theoretical methane production of the cathode chamber (TMPCE) by 8.00-14.10 %, and 11.83-29.30 %, respectively. Consequently, inoculation of Fe-AnGS in MEC could establish and enhance the DIET pathway for methane production.

Automated summary

The magnetite nanoparticle-anaerobic granular sludge complex (Fe-AnGS) was used in microbial electrolysis cells (MEC) to enhance the direct interspecies electron transfer (DIET) pathway for biogas production. Fe-AnGS improved magnetization and conductivity, and enriched specific electrogenic microorganisms. It also increased the gene expression for carbon dioxide reduction and enhanced methane production. Inoculation of Fe-AnGS in MEC established and enhanced the DIET pathway for methane production.