Which of the following is considered a primary treatment method in wastewater management?

The primary treatment method in wastewater management focuses on the initial removal of solids and large contaminants from wastewater. Settling tanks, also known as sedimentation basins or clarifiers, are specifically designed to facilitate this process. In settling tanks, wastewater is allowed to sit undisturbed, enabling heavier solids to settle to the bottom and form sludge, while lighter materials such as grease and scum float to the surface, where they can be removed. This treatment is crucial as it reduces the concentration of solids and organic matter before the wastewater undergoes secondary treatment processes that typically involve biological treatment methods.

In contrast, the activated sludge process and biological nutrient removal are considered secondary treatment methods since they rely on biological processes to further degrade organic matter. Filtration can be part of primary or secondary processes but is not classified as a primary treatment method on its own, as it is more about polishing the effluent rather than the initial stage of waste removal.