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14.12 CHAPTER FOURTEEN

TABLE 14.4 Commonly Manufactured GAC Mesh Sizes

Mesh size Particle diameter range
(U.S. standard sieve size) (mm)
8 × 16 1.18 to 2.36
8 × 20 0.850 to 2.36
8 x 30 0.600 to 2.36
10 × 30 0.600 to 2.00
12 × 40 0.425 to 1.70
14 × 40 0.425 to 1.40
20 × 40 0.425 to 0.85
20 × 50 0.300 to 0.85
Sand 0.38 to 0.65
Anthracite 0.45 to 1.6

tion. As a rule, if the GAC filter effluent concentration is greater than the performance
standard for 3 or more consecutive days, it is time to regenerate or replace the GAC.
Breakthrough depends on the quality of both the influent stream and the design of the
carbon bed. Figure 14.3 illustrates a typical breakthrough curve for a GAC adsorber from
the time of start-up to exhaustion. As the adsorptive capacity of a contactor becomes ex-
hausted at any location in the bed, the zone of adsorption migrates farther down the bed.
Eventually, when there is very little adsorptive capacity left, the contaminant begins to
break through in the effluent. As more and more leakage occurs, the bed becomes ex-

TIME IN OPERATION
FIGURE 14.3 Typical breakthrough pattern for GAC filter.