BACKGROUND An innovative microbial fuel cell (MFC) using Cupriavidus sp. S1 as the biocathode catalyst was developed to improve nitrogen removal from low carbon/nitrogen (C/N) wastewater. RESULTS The desirable external resistance was 100 omega in this study, with an optimal total nitrogen (TN) removal efficiency of 95.71%, and a maximum current density and power density of 7583.89 +/- 318.11 mA m(-3) and 932 mW m(-3) at C/N = 2, respectively, which initially confirmed the ability of Cupriavidus sp. S1 to obtain electrons from the electrode. The maximum tolerance of the system at R-ext of 100 omega was C/N = 1, with a TN removal efficiency of 90.87%. Compared with the open circuit, the TN removal increased by approximately 21.60% and 52.02% at C/N = 2 and 1, respectively, which expanded the application area for the dominant denitrifying bacteria S1. Additionally, the system exhibits the obvious merits of less sludge production, low energy consumption and the recovery of some energy. CONCLUSION Based on these results, domesticated Cupriavidus sp. S1 possesses electrochemical activity. Thus, the system has great potential for efficient and cost-effective nitrogen removal from nitrate-containing low C/N wastewater and energy recovery. (c) 2019 Society of Chemical Industry