What process is used to remove oils and grease from wastewater?

Skimming is the process used to remove oils and grease from wastewater. This technique is effective because oils and greases tend to float on the surface of water due to their lower density. During the skimming process, specific equipment, such as skimmers or a surface skimming device, operates to separate these lighter substances from the wastewater.

This method is commonly employed in primary treatment stages of wastewater treatment facilities, where the removal of floating materials is crucial for maintaining the quality of the water and facilitating further treatment processes. Skimming helps to prevent potential issues caused by the oils and greases, such as blocking pipes or hindering the performance of biological treatment stages downstream.

In contrast, the other processes listed serve different purposes. Evaporation is primarily utilized for concentrating solutions or recovering water through the phase change from liquid to vapor. Centrifugation is a process that separates components of different densities within a liquid, and while it can be used in certain contexts in wastewater treatment, it is not specifically for removing oils and grease from the surface. Oxidation is a chemical process used to reduce or neutralize contaminants in wastewater, but it does not actively remove floating substances like oils and grease.