In sewers the highest non-scouring velocity is achieved in

ANS:A - glazed bricks sewers

The highest non-scouring velocity in sewers is typically achieved in glazed bricks sewers. Explanation:

1. Glazed Bricks Sewers: Glazed bricks sewers are constructed using bricks that have been coated with a layer of glazed material, typically a type of ceramic glaze. This glazing provides a smooth and impervious surface to the sewer pipe interior, reducing frictional resistance and promoting efficient flow of wastewater.
2. Non-Scouring Velocity: Non-scouring velocity refers to the maximum velocity of flow in a sewer pipe that does not cause erosion or scouring of the sewer bed and walls. It is important to maintain a velocity below the scouring threshold to prevent damage to the sewer infrastructure over time.
3. Advantages of Glazed Bricks Sewers: Glazed bricks sewers offer several advantages that contribute to achieving high non-scouring velocities:
   • Smooth Surface: The glazed interior surface of the sewer pipe minimizes frictional resistance, allowing wastewater to flow more freely with reduced energy loss.
   • Resistance to Corrosion: Glazed bricks are resistant to chemical corrosion and biological growth, ensuring long-term durability and minimal maintenance requirements.
   • Hydraulic Efficiency: The smooth surface of glazed bricks promotes laminar flow, reducing turbulence and enhancing hydraulic efficiency.
4. Comparison with Other Sewer Materials: While other sewer materials such as cast iron, cement concrete, and stone ware may also be used in sewer construction, glazed bricks sewers are often preferred for their superior hydraulic performance and resistance to scouring.

In summary, glazed bricks sewers are well-suited for achieving high non-scouring velocities in sewer systems due to their smooth and durable construction. They help optimize hydraulic performance and minimize the risk of erosion or damage to the sewer infrastructure, making them a preferred choice in many sewer applications.