Page 544 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Adsorption 499

Solution Daniel R. Brooks, national sales manager (2004), Calgon
Table CD15.A.1 gives Freundlich isotherm coeffi- Carbon Corporation, Pittsburgh, Pennsylvania, provided the
cients for 141 different synthetic organic compounds photo-micrographs of granular activate carbon used in Figure
15.2. Zachary R. Navarro, Calgon Sales, kindly granted per-
for Filtrasorb 300t; i.e., K(TCE) ¼ 28, 1=n(TCE) ¼
0.62. Apply Equation 15.19 to solve for X* at different mission (2010) to use the images for this current edition.
concentrations of TCE. William C. Lauer, American Water Works Association,
Discussion formerly manager, Denver Potable Water Reuse Plant,
The idea of the problem is to indicate the effect of Denver Water, filled in knowledge about the plant, its evolu-
increasing adsorbate concentration on the capacity of tion, and its design.
GAC to adsorb. The point is that doubling the adsorb- Trina McGuire and Sabrina Hall, Denver Water, facilitated
ate concentration requires, as a rule, less than doubling permissions (2010) to use brochure material from the Denver
of the GAC concentration. Potable Water Reuse Demonstration Plant.
15.9 Estimated Run Time for GAC Reactor at Klein
WTF APPENDIX 15.A: FREUNDLICH ISOTHERM
Given COEFFICIENTS
Let C(TCE) ¼ 20 mg=L in groundwater used as a
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source for GAC treatment. Q(reactor) ¼ 0.022 m =s Table CD15.A.1 is a compilation of Freundlich isotherm
coefficients, i.e., K and 1=n for some 141 organic compounds
(250 gpm); d(reactor) 3.048 m (10.0 ft); h(packed
bed) ¼ 2.44 m (8.0 ft); V(packed bed) ¼ 20.2 m 3 from experimental data of Dobbs and Cohen (1980). A few
3
(714 ft ); mass(GAC) ¼ 9,100 kg (20,000 lb). data are provided for different pH values, e.g., pH ¼ 3, 7, 9.
The compounds were selected based upon the following cri-
GAC ¼ Filtrasorb 300t.
teria: (1) annual production, (2) concentrations that cause
Required
adverse environmental impacts, (3) probability of occurrence
Determine the run time for the reactor to attain com-
in wastewater, (4) persistence in the water environment,
plete saturation as the first column in a series of two.
(5) solubility. During the course of their study, the Occupa-
Compare the result with the 2.5 year run time for the
tional Safety and Health Administration’s list of regulated
column as experienced by the Klein WTP, Commerce
carcinogens was developed, as was the list of ‘‘priority pollu-
City, Colorado.
tants’’ (some 29) named in the consent decree of the USEPA.
15.10 Determination of Headloss and Backwash Velocity
Both these lists are included, i.e., in addition to those selected
Given by the authors. Only one adsorbent, Filtrasorb 300t (Calgon
A GAC column is packed with Filtrasorb 200t. Carbon Corporation 2003b) was used for all experiments.
Hydraulic characteristics are as given in Figure 15.3a Although other Freundlich coefficients are available (in the
and b. Let the column be 9 m in depth, i.e., literature), most of these were generated on an ad hoc basis.
L(reactor) ¼ 9.0 m. The Dobbs and Cohen work is the most extensive and com-
Required prehensive experimental work on isotherms. Concerning
Determine the headloss for the column and the HLR other work, Love et al. (1983) generated Freundlich coeffi-
required for bed expansion. cients for some 17 volatile organic compounds (VOC’s) with
compilation in Table 15.3. Where there is overlap with the
ACKNOWLEDGMENTS Dobbs and Cohen coefficients, the K and 1=n values are
within about 0.01–0.05 fraction of each other.
Staff members of the Klein Water Treatment Facility (Klein
WTF), South Adams Water and Sanitation District, provided GLOSSARY
the information on the plant operation. Roger Dirrim, water
operations and maintenance supervisor (2004) provided the Abrasion number: (1) An index of the resistance of particles
design and operation data for the plant and Charlene Seedle, to physical degradation. (2) Final mean particle dia-
water quality lab supervisor (2004) provided data on meter=original mean particle diameter as determined
operation of the plant and on use of the GC-MS instrument. by an abrasion test involving sieve analysis (USEPA,
Jim Jones, general manager of the district (2010) and 1973, p. B-20).
manager at the Klein WTF (2004), has provided continuing Absorb: The assimilation of matter within the pore structure
hospitality for student field trips and delegations from of a material.
other countries from the time the plant started functioning Activated alumina: A porous, highly adsorptive alumina;
in 1989 and through the decade of the 1990s. The Klein made usually by heating alumina hydrates and used
WTF was named after Jean Klein, long time board president chiefly in drying gases and liquids (http:==unabridged.
and board member, who was instrumental in bringing the merriam-webster.com) [see Chapter 16].
facility into reality. The plant was designed by Harley Bry- Activated carbon: Plant based material that has been processed
ant, PE, Black and Veatch, Denver (BSCE, Colorado State to leave the basic structure, resulting in a large internal
2
University, 1972). surface area, e.g., perhaps 1000 m =gcarbon.