A low-energy intensive electrochemical system for the eradication of Escherichia coli from ballast water: Process development, disinfection chemistry, and kinetics modeling

► Inactivation of Escherichia coli could be achieved within 60s. ► Inactivation of E. coli was obtained with low energy consumption of 0.009kWh/m3. ► Electro-chlorination was the major disinfection mechanism. ► Ozone and free radicals lead to 20% of killing in chloride-free electrolytes. ► Disinfection kinetics model was developed to describe the inactivation of E. coli. The invasion of biological organisms via ballast water has created threats to the environment and human health. In this study, a cost-effective electrochemical disinfection reactor was developed to inactivate Escherichia coli, one of the IMO-regulated indicator microbes, in simulated ballast water. The complete inactivation of E. coli could be achieved within a very short time (150, 120, or 60s) with an energy consumption as low as 0.0090, 0.0074 or 0.0035kWh/m3 for ballast water containing E. coli at concentrations of 108, 107 and 106CFU/100mL, respectively. Electrochemical chlorination was the major disinfection mechanism in chloride-abundant electrolytes, whereas oxidants such as ozone and free radicals contributed to 20% of the disinfection efficiency in chloride-free electrolytes. Moreover, a disinfection kinetics model was successfully developed to describe the inactivation of E. coli.