A power supply system has a power storage device and an ECU, and supplies driving electric power to a load device. The method describes the control of return activated sludge rates, and the operation of partitioned aeration and reaeration zones according to measured properties of the mixed liquor to achieve the claimed benefits. The system is further designed to meet or exceed the Common Criteria EAL-5 or higher rating through incorporation of required security features, as well as a very high level of assurance for handling data at a wide range of sensitivity levels in a wide range of operational environments. The DCPI values include water marks in case of an MPEG stream, Copy Generation Management System codes, EMI in case of an IEEE1394-1995 interface, and user defined DCPI values.