What primary role does the lag unit serve in a lead-lag configuration?

In a lead-lag configuration, the primary role of the lag unit is to serve as a standby unit. This setup typically involves two units: one operating (the lead unit) while the other (the lag unit) is on standby. The lag unit is there to take over if the lead unit fails or requires maintenance, thus ensuring continuous operation without interruption. This redundancy is crucial in operations where consistent processing is necessary, such as in wastewater treatment, as it helps prevent downtime and maintain treatment efficiency.

While increasing reliability is an important aspect of having a lag unit, the explicit purpose of the lag is to be ready to perform when the lead unit is not operational. Similarly, the lag unit does not handle all wastewater inflow; that is primarily the function of the lead unit during normal operations. Additionally, while chemical treatment may benefit from the stable operation of the system, this is not the direct role of the lag unit itself. The primary function remains its capacity to act as a backup, ensuring seamless transitions and continuous processing.