What method is commonly used to remove emulsified oil from wastewater?

Dissolved air flotation is a widely accepted method for removing emulsified oil from wastewater due to its effectiveness in separating lighter-than-water contaminants. In this process, air is dissolved in water under pressure and then released into a flotation tank. As the pressure decreases, the dissolved air forms microbubbles that adhere to the oil droplets, causing them to rise to the surface. The buoyant oil can then be skimmed off, effectively separating it from the water.

This method is particularly beneficial when dealing with emulsions that are difficult to separate through other means, such as gravity settling. Unlike centrifugation, which relies on centrifugal force and may be more costly and energy-intensive, or filtration, which is often ineffective against small oil droplets, dissolved air flotation offers a more efficient solution for emulsified oils. Additionally, the activated sludge process focuses on bacterial treatment for organic matter rather than targeting oil removal, making dissolved air flotation the more appropriate choice for this specific application.