ABSTRACT
The subject of instrumentation and automation techniques represents a very small segment of the total technology of the engineering profession. The most important issue to be resolved concerning automation and instrumentation of an industrial wastewater system is how much instrumentation is necessary. The waste treatment process is to remove solids, to reduce the biochemical oxygen demand of the waste to a suitable level, and to remove any other regulated pollutants. The two most commonly used controllers on flow control in the waste treatment field are the proportional-speed floating controller and the proportional plus reset controller. Controllers are receivers because they respond to a set point input and a report back input. Proportional plus reset controllers are also used in flow control loops. In the floating control system described, proportionality exists between error, pilot valve position, and therefore butterfly valve speed.
