3.1.1 What is the structure called? (1) 3.1.2 Briefly describe how the organic matter decomposes in the structure - NSC Civil Technology Construction - Question 3 - 2017 - Paper 1

Organic matter in the septic tank decomposes through the action of anaerobic bacteria and other microorganisms. These microorganisms break down the solid waste into simpler substances, which eventually allows for the effluent to be released safely into the environment.

The inlet pipe opening at 3.1.B serves to allow wastewater to enter the septic tank. This pipe is crucial for directing the flow of waste into the treatment area.

The inflow at 3.1.B must be lower than the liquid level to prevent backflow and ensure that the wastewater efficiently enters the tank without causing flooding. This also helps maintain the proper level for bacterial activity in the tank.

The effluent at 3.1.D is discharged into the drainage system or an appropriate disposal area, which could include a leach field or an absorption area designed to treat the wastewater further.

Without a ventilation pipe, a drain system may experience several disadvantages, including the buildup of gases like methane, which could lead to unpleasant odors and potential explosions. Additionally, a lack of ventilation can cause pressure changes, leading to drainage issues or blockages.

To effectively illustrate an S-trap, create a sketch showing the curved section of the pipe that creates a water seal. This prevents sewer gases from entering the living space while allowing wastewater to flow through. Ensure the sketch highlights the inlet and outlet points of the S-trap.