What type of receptacle receives discharge from a building's sanitary drainage system and helps in digesting organic matter?

The correct answer is a septic tank. A septic tank is specifically designed to receive discharge from a building's sanitary drainage system, effectively treating and digesting organic matter. The tank functions by utilizing bacteria to break down solids and allow lighter materials, such as fats and oils, to float to the top, forming a scum layer. The clarified liquid effluent is then discharged into a drainage field or leach field where additional treatment occurs through the soil.

The importance of a septic tank lies in its function as a passive treatment system that operates without the need for mechanical methods, allowing for the natural biological decomposition of waste. This makes it a widely utilized option in areas that are not serviced by municipal sewage systems.

While the grease trap does play a role in treating fats, oils, and grease (FOG) before they enter the sanitary drainage system, it does not digest organic matter as a septic tank does. A holding tank is used to temporarily store wastewater without treating it, while a filter chamber functions as a part of advanced systems but does not itself digest the organic matter in the same way a septic tank does.