3.1 What is the structure called? 3.1.1 Briefly describe how the organic matter decomposes in the structure - NSC Civil Technology Civil Services - Question 3 - 2017 - Paper 1

Organic matter decomposes in the septic tank primarily through the action of anaerobic bacteria and other biological life forms such as maggots and worms. These microorganisms break down the waste, leading to the overall reduction of organic materials.

The inlet pipe opening at 3.1.B serves to introduce wastewater into the septic tank, allowing it to enter the system for treatment and decomposition.

The inflow at 3.1.B must be lower than the liquid level to prevent backflow into the drainage system and to maintain a proper pressure differential that aids efficient waste treatment.

The effluent at 3.1.D is typically discharged into a French drain or a specific area designed to allow further filtration and absorption into the ground.

Without a ventilation pipe, a drain system can experience pressure fluctuations that lead to slow drainage or even complete blockages. This may also result in unpleasant odors and the potential build-up of harmful gases, causing health risks.

An S-trap consists of a continuous bend that forms an 'S' shape, which creates a water seal to prevent sewer gases from entering. It has an inlet connecting to the drain and an outlet leading to the drainage pipeline.

The mirror and torch test determines if the drain pipe is STRAIGHT.

The ball of the ball test must be SLIGHTLY SMALLER than the diameter of the pipe.

If the drop in the water level is greater than 6 mm, the pipe probably has a leak.