One embodiment of the present invention provides a system that enables a guardian to monitor a financial account on behalf of an account owner, such as a senior citizen. The selectable torque transfer devices are engaged singly or in combinations to yield an EVT with a continuously variable range of speeds and up to four mechanically fixed forward speed ratios. When the bacteria of flocs within this stage show a switch to anaerobic condition via such coenzyme, the low dissolved oxygen level in the stage is maintained for a preselected period of time or to a preselected extent of the anaerobic condition, before oxygen is added.