The spring 2009 plate settler spacing experiments were run using the process controller software developed by Dr. Weber-Shirk. Our experimental apparatus consisted of four peristaltic pumps, two electric stirrers, one stir-plate, two turbidimeters, one pressure sensor, one solenoid valve, and one pinch valve: all of which were directly controlled by process controller.
The process controller method for the flow rate experiments can be found here.
The following is an overview of how we utilized this software for our apparatus.
States, Set points, and Rules
The process controller software runs based on states, set points, and rules that are inputted by the user: states define the general activity of the system at any given moment; set points are parameters that define the state of the system in greater detail; and rules define the circumstances under which a state occurs.
For example, our process controller method defined two states: "Mix" and "Floc Blanket Formation". The "Floc Blanket Formation" state was characterized by certain flow rates for the influent, alum, and water through the upflow clarifier. These flow rates were the set points. An example of a rule would be:
If the time spent in "Mix" is greater than "x", go to "Floc Blanket Formation".
This rule facilitates a switch from the "Mix" state to the "Floc Blanket Formation" state based on the time set point "x".