LAUSR

Abstract A new type of membrane ecosystem (MES) was constructed by combining the artificial floating ecosystem (AFES) with microfiltration (MF) and nanofiltration (NF) membranes to investigate the removal of 4 antibiotics and 7 antibiotic-resistance genes (ARGs) during 15 days in urban rivers. Two groups of experiments were set, namely no algae/plant group and algae/plant group in which Microcystis aeruginosa and Acorus calamus were planted in the ecological floating island. In no algae/plant group, the removal rate of antibiotics at the outlet of the AFES was 50–78%. However, the abundance of ARGs decreased by less than one order of magnitude. After the combination with algae and plants, the removal of each antibiotic increased by 10–20%, and the ARGs decreased by one order of magnitude or two. MF reached an overall removal rate of 70–95% for antibiotics, while NF was able to achieve over 96%. The log removal rate of each ARGs was 1–4.5, and sul1 decreased most. Quinolones ARGs (qnrD and qnrS) were below the detection limit after MF. In the AFES, sul1, sul2 and qnrS were mainly removed. ermB was always lowest level of all ARGs. After MF and NF, the relative abundance of ARGs changed irregularly, and ermB, qnrS, sul1, sul2 and tetX remained in the NF permeation solution. Conventional indicators (COD, TP, TN, NH4+-N), antibiotics and ARGs except ermB and tetM were correlated with each other. In brief, the MES could control conventional pollution and effectively remove antibiotics and ARGs from river water.