Applications of Equilibrium Thermodynamics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 173

TABLE 4.18
K F and n for Selected Organic Compounds on GAC
Compound K F 1/ n

Benzene 1.0 1.6

Toluene 26.1 0.44

Ethylbenzene 53 0.79

Chlorobenzene 91 0.99

Chloroform 2.6 0.73

Carbon tetrachloride 11.1 0.83

1,2-Dichloroethane 3.5 0.83

Trichloroethylene 28.0 0.62

Tetrachloroethylene 50.8 0.56

Aldrin 651 0.92

Hexachlorobenzene 450 0.60

Source: From Dobbs, R.A. and Cohen, J.M. 1980. Carbon adsorption isotherms
for toxic organics. Report No: EPA-600/8-80-023, U.E. Environmental
Protection Agency, Cincinnati, OH.
Note: The carbon used was Filtrasorb 300 (Calgon Corporation).

will not pass through a 20-size screen. The granular form is less expensive and is
more easily regenerated, and hence is the choice in most wastewater treatment plants.
Activatedcarbontreatmentisaccomplishedeitherinacontinuousmodebyflowing
water over a packed bed of carbon (see Figure 4.12a) or in batch (fill-and-draw) mode
where a given amount of activated carbon is kept in contact with a given volume of
water for a specified period of time (see Figure 4.12b). In the continuous process the
exitconcentrationslowlyreachestheinletconcentrationwhentheadsorptioncapacity
of carbon is exceeded. The bed is subsequently regenerated or replaced.

(b)

(a) Activated carbon

Feed

Euent

Continuous mode
operation

Batch mode
operation

FIGURE 4.12 (a) Continuous mode fixed-bed operation of activated carbon adsorption for
wastewater treatment. Water is passed over a bed of carbon. (b) A batch mode of operation
wherein a fixed weight of carbon is kept in contact with a given volume of aqueous phase.
After treatment the water is replaced. This is also called the fill-and-draw or cyclic, fixed-bed
batch operation. Once the carbon is exhausted it is also replaced with a fresh batch.