Enhanced the treatment of antibiotic wastewater and antibiotic resistance genes control by Fe0-catalyzed microalgal MFCs in continuous flow mode

Abstract

In this study, we propose to operate Fe0-catalyzed microalgae-based MFCs in continuous flow operation mode to explore their antibiotic removal and related biological mechanisms in response to the problems of anode acidification, secondary contamination of cathode electrolyte, and accumulation of antibiotic resistance genes (ARGs) and low efficiency of nitrogen and phosphorus removal in MFCs. The results showed that the removal rates of COD, NH3-N and TN were improved by 14.24 %, 20.27 % and 32.27 %, respectively, in the algae cathode MFC (AC-MFC) compared with the intermittently operated MFCs. The addition of Fe0 not only significantly improved the removal of Chlortetracycline (P < 0.05), but also significantly reduced the risk of transmission of ARGs and mobile genetic elements (MGEs). The addition of Fe0 formed an anaerobic ammonia oxidation and Feammox coupled denitrification mechanism in the anode to achieve enhanced denitrification. At Fe0 = 20 mg/L, the highest output voltage of AC-MFC was 420 mV, corresponding to a power density of 13.39 W.m−3, which was twice as high as when Fe0 was not injected. The dominant phylum mainly included Firmicutes, and the second dominant phylum included Bacteroidota and Proteobacteria. Anaeroarcus spp. with Fe reduction function became the dominant genus in MFC after the addition of Fe0. This study demonstrated that the Fe0-catalyzed microalgal MFCs in continuous flow operation mode not only significantly enhanced antibiotic removal and promoted nitrogen and phosphorus removal, but also effectively controlled the transfer of ARGs. The results can provide a reference for antibiotic wastewater treatment and the control of ARGs.