Evaluation of organic matter and nitrogen removals, electricity generation and bacterial community responses in sediment microbial fuel cell coupled with Vallisneria natans

With the development of industrial civilization, a large amount of carbon and nitrogen compounds from industrial, agricultural, and human activities are discharged into the environment, which has seriously affected the quality of the surface water. The current remediation methods, such as aeration or chemical addition, not only exhibit high energy consumption but may also lead to secondary pollution. This study constructed a sediment microbial fuel cell system coupled Vallisneria natans (P-SMFC) to remove surface water and sediment pollutants, generate electricity, and reduce the demand for additional oxygen supply. P-SMFC demonstrated excellent pollutant removal and power generation performance under three different pollution loads. P-SMFC exhibited a COD removal efficiency of 80.48% at organic loading rate of 10.64 g/(m3d), which was 10.01%, 26.01%, and 41.77% higher than that of normal SMFC system without plants (SMFC), open-circuit control system with plants (C-P), and open-circuit control system without plants (C-S), respectively. P-SMFC exhibited a TN removal efficiency of 92.61% at nitrogen loading rate of 1.06 g/(m3d), which was 17.31%, 9.92%, and 40.58% higher than that of SMFC, C-P, and C-S, respectively. The maximum power density of the P-SMFC was 45.36 mW·m−3, which was 18.57 mW·m-3 higher than that of the SMFC. The oxygen release and root secretion of organic substances by Vallisneria natans promoted the enrichment of microorganisms with power generation and nitrogen removal functions, such as Geobacter, Acidovorax, Nitrosomonas, Pseudomonas, and Delftia. This study developed a novel, sustainable, and low-cost technology for the in-situ remediation of contaminated surface water.