Enhancing carbon and nitrogen removals by a novel tubular bio-electrochemical system with functional biocathode coupling with oxygen-producing submerged plants

Abstract A kind of tubular bio-electrochemical system (BES) with functional biocathode coupling with oxygen-producing submerged plants was developed to remove pollutants from polluted surface water and sediment. The coupled system showed an excellent performance in comparison with normal BES without plants (NP-BES), only plant system (PS) and control system only containing sediment and water (CS). The average removal efficiency of TOC and TN in water of P-BES were 30.3% and 44.7%, which was 2.9 and 2.4 times higher than that of CS. The rate coefficient k of nitrate (2.602) of P-BES was 26.2% lower than that of PS (3.525). The untransformed nitrogen in P-BES accounted for 14.6%, which was 8.0%, 65.2% and 81.0% lower than that in PS, CS and NP-BES. The maximum power density of the coupled system was 20.8 mW/m2, which was 16.8% higher than NP-BES. The microbial community structure analysis indicated that submerged plant altered the structure and abundance of microbial community on cathode, where Pseudomonas, Arthrobacter, Bacillus and Acinetobacter were mainly responsible for the higher pollutant removal and power density than that in NP-BES. This research provided a novel technology for in situ remediation of polluted surface water body.