Accomplishing a N-E-W (nutrient-energy-water) synergy in a bioelectrochemical nitritation-anammox process

This study reports an investigation of the concept, application and performance of a novel bioelectrochemical nitritation-anammox microbial desalination cell (MDC) for resource-efficient wastewater treatment and desalination. Two configurations of anammox MDCs (anaerobic-anammox cathode MDC (AnA(mox)MDC) and nitration-anammox cathode MDC (NiA(mox)MDC)) were compared with an air cathode MDC (CMDC), operated in fed-batch mode. Results from this study showed that the maximum power density produced by NiA(mox)MDC (1,007 mW/m(3)) was higher than that of AnA(mox)MDC (444 mW/m(3)) and CMDC (952 mW/m(3)). More than 92% of ammonium-nitrogen (NH4+-N) removal was achieved in NiA(mox)MDC, significantly higher than AnA(mox)MDC (84%) and CMDC (77%). The NiA(mox)MDC performed better than CMDC and AnA(mox)MDC in terms of power density, COD removal and salt removal in desalination chamber. In addition, cyclic voltammetry analysis of anammox cathode showed a redox peak centered at -140 mV Vs Ag/AgCl confirming the catalytic activity of anammox bacteria towards the electron transfer process. Further, net energy balance of the NiA(mox)MDC was the highest (NiA(mox)MDC-0.022 kWh/m(3) > CMDC-0.019 kWh/m(3) > AnA(mox)MDC-0.021 kWh/m(3)) among the three configurations. This study demonstrated, for the first time, a N-E-W synergy for resource-efficient wastewater treatment using nitritation-anammox process.