A fluid treatment apparatus comprises an electrochemical cell having fluid orifices to receive input fluid and release output fluid, the input fluid having a first level of a microorganism. First and second electrodes are about a water-splitting membrane in the electrochemical cell. A valve controls the flow of fluid through fluid orifices of the electrochemical cell. A power supply supplies a current to the first and second electrodes. A control module comprises program code to operate the valve to flow the input fluid into a fluid orifice of the electrochemical cell and provide a residence time of the fluid in the cell of at least 0.05 minutes, while controlling the power supply to supply to the first and second electrodes, a current having a current density of from about 0.01 to about 20 mA/cm2.