![A 0.80 m deep bed of sand filter (length 4 m and width 3 m) is made of uniform particles (diameter = 0.40 mm, specific gravity = 2.65, shape factor = 0.85) with bed porosity of 0.4](https://www.gkseries.com/blog/wp-content/uploads/2023/07/A-0.80-m-deep-bed-of-sand-filter-length-4-m-and-width-3-m-is-made-of-uniform-particles-diameter-0.40-mm-specific-gravity-2.65-shape-factor-0.85-with-bed-porosity-of-0.4.jpg)
Q. A 0.80 m deep bed of sand filter (length 4 m and width 3 m) is made of uniform particles (diameter = 0.40 mm, specific gravity = 2.65, shape factor = 0.85) with bed porosity of 0.4. The bed has to be backwashed at a flow rate of 3.60 m3/min. During backwashing, if the terminal settling velocity of sand particles is 0.05 m/s, the expanded bed depth (in m, round off to 2 decimal places) is
Solution:
![](https://www.gkseries.com/blog/wp-content/uploads/2023/07/Screenshot-427.png)