Unique roles of conductive/redox additives on humification in electric field-assisted composting

Electric field-assisted composting (EC) is a novel technology for enhancing compost humification. Elucidating the role of electric field application in promoting humification and identifying enhancement strategies remains a key challenge. This study investigated the role of conductive and redox pathways in enhancing the humification efficiency of EC systems through the incorporation of conductive graphite and sodium lignosulfonate. Compared with EC, the conductive graphite treatment (EGPC) and sodium lignosulfonate treatment (ESLC) increased current intensity by 2.5- and 1.8-fold, respectively. Additionally, humic acid (HA) content increased by 62.34 % in EGPC and 60.86 % in ESLC. EGPC treatment increased the abundance of Bacillus and enhanced synergistic interactions among core bacteria. Conversely, ESLC treatment significantly altered β-diversity and increased the abundance of Flavobacterium during composting. Correlation analysis and partial least squares path modeling indicated that EGPC treatment promoted direct electron transfer and bacterial interactions, thereby enhancing organic matter humification. ESLC treatment improved bacterial community diversity and facilitated the conversion of furanic acid into HA. These findings provide a theoretical basis for optimizing EC and highlight its potential for large-scale application.