Quorum sensing signals from sludge improving the self-assembly of electrode biofilms in microbial fuel cells for chloramphenicol degradation

The requirement of efficient and robust electrode biofilms is critically important to bioelectrochemical systems (BESs), especially for antibiotic wastewater treatment. In this study, different stratified extracellular polymeric substances (ALL-EPS, SEPS, LB-EPS and TB-EPS) extracted from sludge and the corresponding EPS with N-acyl-homoserine lactones (AHLs) removed (ALL-EPS-1, SEPS-1, LB-EPS-1 and TB-EPS-1) were added with increasing concentrations of chloramphenicol (CAP) to investigate their effects on the acclimation of anode biofilms in CAP-degrading microbial fuel cells (MFCs). The results revealed that AHLs in stratified sludge EPS played a key role in facilitating the self-assembly of anode biofilms, causing elevated power production and CAP elimination. The highest power density (498.17 mW m⁻²) and CAP removal rate (1.21 ± 0.04 mg L⁻¹ h⁻¹) were attained in the TB-EPS MFC, which were 2.57 and 2.03 times higher than those in the TB-EPS-1 MFC, respectively. The superior physicochemical characteristics (3D porous structure, more biomass, stronger cell viability and more conductive substances in biofilm EPS) and mutualistic microbial community (richer biodiversity, higher average microbial ratios, more bifunctional microbes and stronger positive microbial interactions) of the biofilms regulated by AHLs led to the outstanding performances. The findings provide new insights from quorum sensing into the rapid start-up and stable operation of BESs for recalcitrant pollutant degradation.