What process is considered the opposite of gravity separation in wastewater treatment?

In the context of wastewater treatment, the process that is considered the opposite of gravity separation is floatation. Gravity separation relies on the principle that heavier particles settle to the bottom of a container due to gravity, facilitating the removal of solids from liquids. In contrast, floatation involves the rising of suspended particles to the surface of the liquid, allowing them to be removed as scum or foam.

Floatation typically utilizes air or gas bubbles that adhere to the particles, causing them to become buoyant and rise. This method is particularly effective for removing lighter materials, such as oils, fats, and certain types of solids that may not settle easily by gravity. The combination of bubble attachment and the reduction of density allows these materials to be separated from the wastewater efficiently.

This contrasts with processes like filtration, absorption, and oxidation, which are different in function and application within the realm of wastewater treatment. Filtration primarily involves the physical barrier that allows liquid to pass while trapping solids, and absorption refers to a chemical interaction where substances adhere to each other. Oxidation is a process involving the chemical transformation of compounds, often to break down pollutants, rather than separating them based on density or buoyancy. Thus, floatation stands alone as the mechanism directly opposing gravity separation