Effect of start-up strategies with functionally redundant and efficient acetoclastic electroactive bacteria on the performance of microbial electrolysis cells fed with domestic wastewater

Different start-up strategies were investigated for enriching efficient acetoclastic electroactive bacteria (EAB) in wastewater-fed microbial electrolysis cells (MECs). Wastewater-fed MECs bioaugmented (B-MECs) at time zero with pure cultures of Geobacter sulfurreducens and Desulfuromonas acetexigens or pre-enriched anode biofilm (PEA-MECs) with G. sulfurreducens and D. acetexigens performed better than wastewater-fed MECs started with wastewater (WW-MECs) as the sole inoculum. The highest peak current (1575 ± 157 mA/m²), coulombic efficiency (70.3 ± 9 %), and CH₄ production (0.27 ± 0.02 L/g-COD) was observed in PEA-MECs. The relative abundance of acetoclastic EAB was influenced by start-up strategies (Geobacter: 23.9 ± 2.6 % and Desulfuromonas: 13.7 ± 6 % for B-MECs; Geobacter: 29.6 % ± 5.1 % and Desulfuromonas: 0.45 ± 0.2 % for PEA-MECs; Geobacter: 7.9 ± 0.5 % for WW-MECs). These results provide a novel insight for enriching the anode with functionally redundant and efficient acetoclastic EAB, which is crucial for resource recovery from wastewater.