Science of Water : Concepts and Applications

370 The Science of Water: Concepts and Applications
Solution:
Example 10.77
total gallons filtered
UFRV
2
filter surface area, ft
2,220, 000 gal
(18 ft)(18 ft)
6852 gal ft 2
Problem:
The total water fi ltered during a fi lter run is 4,850,000 gal. If the fi lter is 28 ft by 18 ft, what is the unit
fi lter run volume in gal/ft2 ?
Solution:
total gallons filtered
UFRV
2
filter surface area, ft
4,850, 000 gal
(28 ft)(18 ft)
9623 gal ft 2
Equation 10.69 can be modifi ed as shown in Equation 10.70 to calculate the unit fi lter run
volume given fi ltration rate and fi lter run data.
Example 10.78
2
UFRV (filtration rate, gpm ft )(filter run time, min)
(10.70)
Problem:
The average fi ltration rate for a fi lter was determined to be 2.0 gpm/ft2 . If the fi lter run time was
4250 min, what was the unit fi lter run volume in gal/ft2 ?
Solution:
2
UFRV (filtration rate, gpmft )(filter run time, min)
2
(2.0 gpmft
)(4250 min)
8500 galft 2
The problem indicates that at an average fi ltration rate of 2.0 gal entering each square foot of fi lter each
minute, the total gallons entering during the total fi lter run is 4250 times that amount.
Example 10.79
Problem:
The average fi ltration rate during a particular fi lter run was determined to be 3.2 gpm/ft2 . If the fi lter
run time was 61.0 h, what was the UFRV in gal/ft2 for the fi lter run?