Design the backwash system for Laramie’s rapid sand filter. Use the filter dimensions fr...

Design the backwash system for Laramie’s rapid sand filter. Use the filter dimensions from Problem 8-19 . The backwash system includes the layout of the backwash troughs, backwash velocity, flow rate of backwash water per trough, the trough dimension (width and depth), trough elevation, volume of backwash tank, and elevation of the lowest water level in the backwash tank.

Problem 8-19

In the continuing design of Laramie’s rapid sand filter ( Problems 8-12 , 8-13 and 8-17 ), determine the area of each filter cell and the plan dimensions of a filter box. Assume a gullet width of 0.8 m.

Problems 8-12

The rapid sand filter being designed for Laramie has the characteristics shown below. Using the Rose equation, determine the headloss for the clean filter bed in a stratified condition.

Problems 8-13

Determine the maximum backwash rate and the height of the expanded bed for the sand used in Problem 8-12.

Problems 8-17

Determine the number of filter beds for Laramie ( Problem 8-12 ) if the maximum day design flow rate is 55,000 m³/d.