Degradation performance and microbial community analysis of microbial electrolysis cells for erythromycin wastewater treatment

Antibiotics represent a major environmental health concern worldwide. In this study, a high concentration of erythromycin (ERY) was degraded by using single-chamber MECs with carbon cloth anodes. The electrochemical characteristics of MECs and the correlation with ERY were analysed. High-performance liquid chromatography analysis showed that the removal of ERY reached 99% when the influent concentration of ERY was 20 mg/L. In addition, ermG was the most common antibiotic resistance gene, whether in the reactor effluent (3.37 x 10(5) copies/mu L DNA) or in the anode biofilm (0.21 x 10(5) copies/mu L DNA), while ermA was not detected. The SEM images indicated that the anodic and cathodic biofilm were mature and well-constructed. High throughput sequencing of 16S rDNA gene amplicons indicated that Geobacter, as a known genus of exoelectrogenic bacteria, is very dominant in the reactor anode biofilm, with a relative abundance of 77.0%. Acetoanaerobium was widely present in the biocathode. These results indicate that MECs can be considered to be a useful and reliable technology for improving ERY biodegradation efficiency in wastewater, thus providing a meaningful economic output and efficient operation in future scale-ups.