According to the definition of septic tanks, what is NOT a function listed?

The correct answer highlights that filtration of nutrients from the wastewater is not a primary function of septic tanks. Septic tanks are designed to treat wastewater through the processes of settling, anaerobic digestion, and storage of solids and liquids.

The process begins when wastewater flows into the septic tank, where heavier solids settle at the bottom, forming a layer of sludge. Lighter materials, like scum, float to the surface, and the middle layer consists of clarified effluent.

The key functions of septic tanks include clarification of effluent, where the separated liquid can be further treated or absorbed into the ground; subsurface absorption, where the effluent is dispersed into a leaching field for final treatment by the soil; and the storage of scum and solids, which are decomposed over time but require periodic pumping.

While nutrients may be broken down in the tank, they are not filtered in the conventional sense. Instead, the role of a septic tank is more about separation and settling rather than specifically filtering nutrients. This distinguishes the primary functions of septic tanks from nutrient filtration, which is not part of their intended operation.