Water and Wastewater Engineering - Sciences Club

11-15.
11-16.
11-17.
What effect does removing the 100–140 sieve fraction have on the depth of the expanded
bed in Example 11-3 ?
Determine the number of filter beds for Eau Gaullie ( Problem 11-10 ) if the maximum
day design flow rate is 3,800 m 3 / d.
Determine the number of filter beds for Laramie ( Problem 11-12 ) if the maximum
day design flow rate is 55,000 m 3 / d.
11-18. In the continuing design of Eau Gaullie’s rapid sand filter ( Problems 11-10 , 11-11 ,
and 11-16 ), determine the area of each filter cell and the plan dimensions of a filter
box. Assume a gullet width of 0.5 m.
11-19. In the continuing design of Laramie’s rapid sand filter ( Problems 11-12 , 11-13 and
11-17 ), determine the area of each filter cell and the plan dimensions of a filter box.
Assume a gullet width of 0.8 m.
11-20.
11-21.
Design the backwash system for Eau Gaullie’s rapid sand filter. Use the filter dimensions
from Problem 11-18 . 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.
Design the backwash system for Laramie’s rapid sand filter. Use the filter dimensions
from Problem 11-19 . 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.
11-22. Determine the gullet dimensions for Eau Gaullie’s rapid sand filter. Use the filter dimensions
from Problem 11-18 and the backwash rate from Problem 11-20 . Assume a
250 mm diameter pipe from the gullet is to carry the wash water at a velocity of
0.9 m/s.
11-23. Determine the gullet dimensions for Laramie’s rapid sand filter. Use the filter dimensions
from Problem 11-19 and the backwash rate from Problem 11-21 . Assume
a 700 mm diameter pipe from the gullet is to carry the wash water at a velocity of
1.2 m/s.
11-24.
Determine the depth of the filter box for Eau Gaullie’s sand filter. Use the clean bed
headloss from Problem 11-10 and velocity headloss from Problem 11-22 . Assume
the minimum depth of water above the filter bed is 2.4 m, that the gravel is 0.25 m
deep, and that the depth of the underdrain is 0.25 m.
11-25. Determine the depth of the filter box for Laramie’s sand filter. Use the clean bed
headloss from Problem 11-12 and velocity headloss from Problem 11-23 . Assume
the minimum depth of water above the filter bed is 2.4 m and that an IMS drain that
is 30 cm deep is used.
11-26. Design the structural components * of a rapid sand filter for the village of Waffle. The
maximum day flow rate is 8,700 m 3 /d. The design criteria and sand analysis are given
*These do not include the pipe gallery or control system.
GRANULAR FILTRATION 11-51