Coupled Effects of Electrical Stimulation and Antibiotics on Microbial Community in Three-Dimensional Biofilm-Electrode Reactors

Antibiotics are often misused or overused, resulting in large residue inputs in the environment. Electricity and antibiotics were regarded as potentially important factors, which impact on the microbial community during treatment of antibiotics in three-dimensional biofilm-electrode reactors (3D-BERs). Unfortunately, only a few studies have been reported yet. Four 3D-BERs and one 3D-BR (reactor with biological sludge and no voltage) were designed to assess the effect of low current, sulfamethoxazole (SMX), and tetracycline (TC) on microbial populations. The 3D-BERs achieved excellent removal efficiencies of 72.20–93.52 and 82.61–95.80% for SMX and TC, respectively. Microorganisms were classified into 58 phyla, 125 classes, 166 orders, 187 families, and 220 genera. Proteobacteria held the overwhelming predominance, followed by Bacteroidetes, Chloroflexi, Actinobacteria, Verrucomicrobia, Firmicutes, and Acidobacteria. The 3D-BERs achieved higher richness of microbial composition compared with the 3D-BR. Microbial communities and relative abundance at the phyla level were affected by low current. The microbial communities in the 3D-BERs were similar at the genus level, even with different antibiotic concentrations. However, the relative abundances and compositions of the microbial communities decreased during the treatment of antibiotics. To increase the performance of 3D-BERs, the function of microorganisms should be investigated in future studies.