The correct answer is: A. Used to remove the grease and oil.
Skimming tanks are used to remove grease and oil from wastewater. They are typically rectangular tanks with a sloped bottom that allows the grease and oil to float to the surface. The grease and oil are then skimmed off the surface and disposed of.
Option B is incorrect because sludge is not skimmed out of skimming tanks. Sludge is a solid waste that is produced during the treatment of wastewater. It is typically composed of organic matter, bacteria, and other solids. Sludge is removed from wastewater treatment plants and disposed of in landfills or incinerated.
Option C is incorrect because skimming tanks are not provided with self-cleaning screens. Self-cleaning screens are used to remove
large objects, such as rags and paper, from wastewater. They are typically made of metal or plastic and have a series of openings that allow water to flow through but trap large objects.Option D is incorrect because skimming tanks are not improved versions of grit chambers. Grit chambers are used to remove sand and grit from wastewater. They are typically rectangular tanks with a sloped bottom that allows the sand and grit to settle to the bottom. The sand and grit are then removed from the tank and disposed of.