Which processes are primarily responsible for the removal of BOD in wastewater treatment?

The removal of Biochemical Oxygen Demand (BOD) in wastewater treatment is primarily achieved through aeration and the action of microorganisms. BOD is a measure of the organic matter present in the water that can be broken down by biological processes. During aeration, air is introduced into the wastewater, which promotes the growth of aerobic microorganisms.

These microorganisms use the organic matter as a food source, effectively breaking it down and thus reducing the BOD levels in the treated water. This biological treatment is crucial because lower BOD levels indicate a cleaner effluent that will have less environmental impact when released into receiving bodies of water.

The other processes listed, such as filtration and chemical treatment, mainly serve different purposes, like removing suspended solids or disinfecting water. Settling and skimming are more focused on the physical separation of solids from liquids, while incineration and evaporation are methods used for different types of waste treatment and disposal rather than specifically targeting BOD removal in wastewater.