Microbial electrochemical technologies (METs) uses electro-bioremediation systems that can treat groundwater contaminated with nitrate and arsenite simultaneously. A continuous-flow bioelectrochemical reactor has been developed that reduces nitrate into harmless dinitrogen gas while oxidizing toxic arsenite into less harmful arsenate. The system can achieve high nitrate removal rates and over 95% arsenite oxidation efficiency under groundwater-like conditions. This works as the internal recirculation significantly improves treatment performance by enhancing mass transfers and microbial activity of denitrifying and arsenite-oxidizing bacteria like Sideroxydans sp and Achromobacter sp. Thus, electro-bioremediation as a sustainable, low-chemical, and energy-efficient solution for complex groundwater contamination challenges.