A sand-bed filter of 3.6 m in diameter, is used for the clarification of waste water at atmospheric pressure and temperature. a) The bed is packed to...

A sand-bed filter of 3.6 m in diameter, is used for the clarification of waste water at atmospheric pressure and temperature.

a) The bed is packed to a depth of 1.2 m of fairly uniform coarse sand particles with volume diameter (dv) of 1080 mm, sphericity (y) of 0.8, and voidage (e) of 0.5. For a constant water level of 3.0 m above the sand, calculate the flow rate of water through the sand bed.

[Hint: Use the Ergun equation in full, with superficial velocity as unknown variable.]