What role does a clarifier play in a wastewater treatment plant?

A clarifier plays a crucial role in a wastewater treatment plant by allowing solids to settle out of the wastewater after treatment processes. During this stage, the wastewater containing suspended solids flows into the clarifier where, due to gravity, the heavier solids settle to the bottom, forming a sludge layer. This separation is critical because it helps to remove impurities from the water, leading to cleaner effluent that is less harmful when discharged into the environment or further treated.

While the other options relate to important functions within a wastewater treatment facility, they do not accurately describe the primary function of a clarifier. Adding chemicals for disinfection is a process that takes place later in treatment, while storing wastewater before treatment and aerating for biological processes refer to different stages in the treatment chain. Hence, the clarifier's specific function in settling out solids is essential for effective wastewater treatment and improving overall water quality.