What is the process of settling in wastewater treatment?

The process of settling in wastewater treatment refers to the method where solid particles in the wastewater are allowed to sink to the bottom of a tank, separating them from the liquid. This is crucial in the treatment process because it helps to remove larger solids from the liquid waste, resulting in clearer water above the settled sludge.

During settling, the weight of the solid particles causes them to drop out of the wastewater due to gravity. This action not only aids in clarifying the water but also prepares it for further treatment processes, such as filtration or biological treatment. The tank used for this purpose is often called a sedimentation tank or clarifier.

In contrast, filtering out small particles would involve using a medium to capture those particles, which is a different process. Evaporating water from the system focuses on removing moisture rather than dealing with solids. Mixing chemicals into the wastewater often pertains to disinfection or altering the chemical properties of the water, rather than physical removal of solids through settling. Therefore, the correct answer effectively captures the essence of the settling process in wastewater treatment.