Fundamentals of Adsorption onto Activated Carbon in Water and Wastewater Treatment - Activated Carbon for Water and Wastewater Treatment - page 31

Q/A Hydraulic Loading Rate
EBCT V B /Q

Q

A: cross-sectional area

L B :
Packed bed
height

GAC
particles

V B :
Bed volume

Figure 2.5 Downflow fixed-bed GAC adsorber.

up- or downflow systems consisting of one or more vessels in series or in parallel.
The main parameters characterizing the GAC operation are as follows:

2.3.2.3.1 Empty-Bed Contact Time (EBCT) The EBCT is calculated as the total
volume of the carbon bed divided by the flow rate of water:

V B
Q

EBCT ¼ ð 2 : 12 Þ

where

volume of the GAC bed (L 3 )

V B ¼

flow rate (L 3 /T) Q ¼

EBCT can also be expressed as follows:

L B
Q

EBCT ¼ ð 2 : 13 Þ

= A

where

L B ¼ depth of GAC bed, (L)

cross-sectional area of bed, (L 2 ) A ¼

hydraulic loading rate (HLR), (L 3 /L 2 .T) Q = A ¼

The EBCT represents the theoretical residence time in the filter in the absence
of packing media. Therefore, it is actually a fictive parameter whose mean-
ingfulness has been discussed in water treatment [35].