What type of process is a sedimentation tank primarily considered?

A sedimentation tank is primarily considered a physical process because it relies on the principles of gravity to separate solid particles from liquid wastewater. In this process, the heavier solids settle to the bottom of the tank due to gravitational forces, forming a sludge layer, while the clearer water remains at the top. This effective separation does not involve any chemical reactions, biological activity, or significant changes in temperature, which are characteristics of chemical, biological, and thermal processes, respectively. Therefore, the operation of sedimentation tanks is fundamentally grounded in physical properties and mechanisms.