What is Sewage?
Sewage is wastewater that is produced by people (domestic/municipal), which contains large amounts of water and other matters such as organic and inorganic impurities.
The source of sewage might be from typical household water use, such as a bathroom, toilet, kitchen, and also by industries, offices, hospitals, and factories.
There are two types of sewage: one is treated wastewater, and the other one is untreated sewage.
The transport facility or infrastructure that requires to transport the collected sewage from the source to a treatment plant or a particular environment for disposal is known as a sewage system.
The sewage system consists of sewers, manholes, collection chambers.
Sewers is an underground pipe or conduit to transport the collected wastewater (sewage) from the source to its endpoint.
Here we are going to discuss the sewers and its types.
Points to be considered to select the right type
While choosing the type of sewers for the transport below points to be considered
- It should have sufficient strength and durability to transport and resist the forces acting on it.
- It should have excellent abrasion resistance. There are a lot of impurities present in the sewage, which will flow in high velocity and cause wear and tear to the surface.
- It should be corrosion resistant. Since sewage contains deadly gases and high-level Ph water, which might cause corrosion to the sewer.
- It should be lightweight to handle
Types of sewers
According to their make, there are 7 types of sewers.
- Asbestos Cement Sewer
- Brick Sewer
- Cement Concrete Sewer
- Cast iron Sewer
- Steel Sewer
- Stoneware sewer
- Plastic Sewer
Let’s discuss each in detail
Asbestos Cement (AC) Sewer
The sewer made of a mixture of asbestos fibre, silica, and cement is known as Asbestos Cement Sewer. This type is suitable for household sewage used for vertical transmissions like a kitchen sink or a bathroom to the collector.
- It has smooth interiors.
- Easy to cut, connect, fit, and drilled.
- It is lightweight and easy to handle.
- It is not suitable for high-velocity sewage.
- It is not suitable for underground situations.
- It is available in sizes ranging from 10 – 100 cm internal diameter and up to 4 metre lengths.
- It is not sulphate resistant and is subjected to acid attacks, which reduces its strength and durability.
As the name suggests, it is made of a special type of brick. These sewers are used to carry the stormwater drains.
- It can be constructed at any shape and size according to the need.
- It is plastered at the outside in the joints to stop the entry of tree roots.
- They are used as a combined sewer to collect rainwater, stormwater as well as normal sewage.
- The internal lining needs to be done to make the interior smooth and to make it corrosion resistant.
Cement Concrete Sewer
Cement Sewer is made of reinforced cement concrete.
- It has high abrasion resistance.
- It has high durability and strength.
- It is heavyweight and hard to transport.
- It ranges from 150 mm to 900 mm in diameter.
- It can withstand high-velocity flows, which cause heavy imposed loads.
Cast Iron Sewer
Cast Iron pipes are made from Pig Iron, which is an intermediate material produced in the industry.
- It has excellent abrasion resistance.
- It is costly because of the made.
- It withstands high internal pressure and external pressure.
- It is suitable for high-velocity flow and heavy imposed loads.
- It is suitable for inverted siphons (discussed in cross drainage works).
- It is suitable for dense load areas such as below highways and railways.
- Because of the make, the cast iron sewers are very strong and durable.
- It is difficult to repair the cast iron sewers.
- Steel pipes are not corrosion-resistant, so they need a galvanized coating to protect it.
- Steel pipes withstand high pressure, vibrations, and shocks.
- It is not suitable for partial flow sewers since it exposes the conduit to possible corrosion.
Stoneware sewers are more like bricks.
They are made from clay or shale, which will be grounded to particles and then mixed with water to make a pipe shape. After that, the clay will be put up in a kiln and heated upto 150 deg celsius for several hours.
- It is heavy and difficult to transport.
- It is suitable for household drainage.
- It is very cheap compared to other types.
- It is exceptionally durable and corrosion-resistant.
- If properly burnt and laid, It can withstand heavy backfilling and traffic.
Plastic sewers are very common nowadays.
- It has a smooth internal surface.
- It is lightweight and easy to handle.
- It is easy to lay, cut, join, and fit them.
- It is suitable for household drainage works.
- They are very durable and corrosion-resistant.
Shapes of Sewers
Generally, sewers are circular in shape and easy to transport the sewage with its smooth finish. However, like types of sewers sometimes other shapes are also used for reasons such as
- To Increase the strength
- For Easy Maintenance
Happy Learning 🙂