ABSTRACT
Manual measurements of process control variables are often infrequent, may lack the desired precision, and often cannot be made within the short span of time necessary for proper operation of the facility. The subject of instrumentation and controls is very complex, requiring an extensive background for those involved in design, analysis, and selection of instrumentation for wastewater treatment facilities. This chapter presents process control strategies, physical and chemical measuring elements and instruments, computers, and final control elements that are integral parts of the process control systems for a wastewater treatment facility. It also presents the type of instrumentation and control devices and simplified control loop diagrams selected for various treatment processes in the design example. The benefits of installing a sophisticated instrumentation and control system in wastewater treatment may be in process improvement, equipment performance, and convenience to personnel. In continuous process control, there are two types of process variables: the uncontrolled variable and the controlled variable.
