What category does NOT belong among types of control systems?

Project control does not belong among the types of control systems in the context of wastewater management and treatment processes. Wastewater control systems are primarily designed to manage processes directly related to the treatment and handling of wastewater. These control types include manual on/off control, proportional control, and ratio control, which are instrumental in ensuring that treatment processes are efficient and effective.

Manual on/off control is a straightforward control method where an operator physically controls the system, often as a way to manage equipment or processes in a binary manner. Proportional control adjusts the output based on the error signal, maintaining a balance in the system, which is crucial for processes requiring precise chemical dosing or flow management. Ratio control involves maintaining a specific proportion between two or more variables, critical for processes where the relationship between inputs can affect treatment outcomes.

In contrast, project control refers to managing the planning, execution, and monitoring of a project, which is not specifically a type of control system related to wastewater treatment. It encompasses broader aspects of project management such as timelines, budgets, and resource allocation, making it distinct from the operational control methods used in wastewater systems.