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ACTIVATED CARBON PROCESSES 14.27

~lFlushingWater
Header

Water Level

GAC Fill
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~
"-- GAC --~

~- Underdrain
Underdrain
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Lateral -7

FIGURE 14.13 Cross section through a typical, open-top concrete, rectangular, gravity flow GAC con-
tactor. (Adapted from Westerhoff and Miller, 1986.)
• Rate at which backwash water must be applied because this is a function of contactor
surface area
• Ability to provide uniform distribution of backwash water over the effective maximum
area of a single unit
• The ability to accommodate a reduction in capacity with one unit out of service for
backwash, regeneration, or maintenance