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PREDICTING THE PERFORMANCE OF<br />

FIXED-BED GRANULAR<br />

ACTIVATED CARBON ADSORBERS<br />

D. W. Hand, J. C. Crittenden, D. R. Hokanson, and J. L. Bulloch<br />

Dept. <strong>of</strong> Civil and Environmental Engineering<br />

<strong>Michigan</strong> Technological University<br />

Houghton, <strong>Michigan</strong> 49931<br />

USA<br />

Presented at First IAWQ Specialized Conference on Adsorption in Water<br />

Environment and Treatment Processes; Shirahama, Wakayama Japan<br />

November 1996<br />

Copyright © 1996-2002. <strong>Michigan</strong> Technological University. All Rights Reserved.<br />

1


OUTLINE<br />

Competitive Interactions<br />

Between Known Components<br />

• Correlation <strong>of</strong> Single Solute Adsorption Equilibria<br />

• Prediction <strong>of</strong> Multicomponent Equilibria <strong>of</strong> Known<br />

Components<br />

• Model Predictions Using <strong>the</strong> Equilibrium Column<br />

Model<br />

• Model Predictions Using <strong>the</strong> Pore Surface Diffusion<br />

Model<br />

2


OUTLINE (continued)<br />

Syn<strong>the</strong>tic Organic Compound (SOC) and Unknown<br />

Background Organic Matter (BOM) Interactions<br />

• Impact <strong>of</strong> BOM on Fixed Bed Adsorption Capacity <strong>of</strong><br />

SOCs<br />

– Influence <strong>of</strong> Exposure Time<br />

– Influence <strong>of</strong> Compound Type<br />

– Influence <strong>of</strong> Water Type<br />

• Impact <strong>of</strong> BOM on Adsorption Rate<br />

• Model Simulations for a Variety <strong>of</strong> Waters<br />

3


Volume Adsor<strong>bed</strong> (ml/g)<br />

1<br />

0.1<br />

0.01<br />

0.001<br />

0.0001<br />

ISOTHERM CORRELATION<br />

Data from 26 chemicals<br />

Correlation<br />

Adsorbent: Calgon F-400 GAC<br />

Data Source: Speth and Miltner (1990)<br />

Wi = Woexp[-β(ε i/Vi) σ ]<br />

Wo = 0.24 ml/g<br />

β = 0.0025 (ml/cal) σ<br />

σ = 1.51<br />

0 50 100 150 200 250<br />

Adsorption Potential / Intrinsic Molar Volume (cal/ml)<br />

4


Volume Adsor<strong>bed</strong> (ml/g)<br />

0.01<br />

0.001<br />

0.0001<br />

MTU DATA FOR SIX COMPONENTS<br />

10<br />

1<br />

0.1<br />

Naphthalene<br />

1,2,4-Trichlorobenzene<br />

Trichloroethylene<br />

Toluene<br />

m-Xylene<br />

Correlation<br />

Adsorbent: Calgon APA GAC<br />

Particle Size: 200 x 400 USTM<br />

Data Source: Bulloch et al. (1995)<br />

Wi = Woexp[-β(ε i/Vi) σ ]<br />

Wo = 1.03 ml/g<br />

β = 0.045 (ml/cal) σ<br />

σ = 1.00<br />

0 20 40 60 80 100 120 140 160<br />

Adsorption Potential / Intrinsic Molar Volume (cal/ml)<br />

5


IDEAL ADSORBED SOLUTION THEORY<br />

C<br />

i<br />

=<br />

g q<br />

i i<br />

N<br />

Â<br />

j=<br />

1<br />

• Wilson Activity Coefficients<br />

q<br />

j<br />

L<br />

M<br />

NM<br />

N<br />

Â<br />

j=<br />

1<br />

nq<br />

nK<br />

i i<br />

ln = 10 . -ln xA-<br />

g i j ij<br />

j=<br />

1<br />

n<br />

Â<br />

j j<br />

( 1-zi<br />

)<br />

i i<br />

g = a<br />

n<br />

Â<br />

k = 1<br />

O<br />

P<br />

QP<br />

L<br />

M<br />

NM<br />

n<br />

Â<br />

j=<br />

1<br />

x A<br />

k ki<br />

xA<br />

j kj<br />

• Empirical Activity Coefficients (less than 1.0)<br />

O<br />

P<br />

QP<br />

6


Solid Phase Concentration<br />

(mMol/g)<br />

10<br />

1<br />

0.1<br />

0.01<br />

IAST CALCULATIONS SHOWING<br />

IMPROVEMENT WITH γ<br />

Adsorbent: Calgon F-400 GAC<br />

Particle Size: 200 x 400 USTM<br />

Temperature: 13 o C<br />

Data Source: Arora (1989)<br />

0.00001 0.0001 0.001 0.01 0.1<br />

Liquid Phase Concentration (mMol/L)<br />

Multicomponent DBCM Data Original DBCM IAST Prediction<br />

DBCM IAST Fit DBCM Single Solute<br />

Multicomponent PCE Data Original PCE IAST Prediction<br />

PCE IAST Fit PCE Single Solute<br />

7


Solid PhaseConcentration<br />

(mMol/g)<br />

0.1<br />

0.01<br />

0.001<br />

IAST CALCULATIONS SHOWING NO<br />

IMPROVEMENT WITH γ<br />

1<br />

Adsorbent: Calgon F-400 GAC<br />

Particle Size: 200 x 400 USTM<br />

Temperature: 13 o C<br />

Data Source: Arora (1989)<br />

0.00001 0.0001 0.001 0.01 0.1<br />

Liquid Phase Concentration (mMol/L)<br />

Multicomponent Chlor<strong>of</strong>orm Data Original Chlor<strong>of</strong>orm IAST Prediction<br />

Chlor<strong>of</strong>orm IAST Fit Chlor<strong>of</strong>orm Single Solute<br />

Multicomponent TCE Data Original TCE IAST Prediction<br />

TCE IAST Fit TCE Single Solute<br />

8


Solid-phase Concentration, (mg/g)<br />

ADSORPTION EQUILIBRIUM ISOTHERM<br />

FOR TRICHLOROETHENE<br />

100<br />

10<br />

1<br />

TRICHLOROETHENE ISOTHERMS<br />

PRELOADING TIME IN WEEKS<br />

CALGON F-100 GAC (12x40 mesh)<br />

v = 10 m/hr<br />

Source: Zimmer et al. (1988)<br />

Single Solute (q=3.27 C 0.458 )<br />

34<br />

70<br />

100<br />

2<br />

7<br />

25<br />

50<br />

1 10 100 1000<br />

Liquid-Phase Concentration, (mg/m 3 )<br />

9


Relative Freundlich Parameter K %<br />

120<br />

100<br />

80<br />

60<br />

40<br />

20<br />

0<br />

FREUNDLICH K REDUCTION<br />

FOR VARIOUS WATERS<br />

Houghton GW<br />

(F-400 GAC)<br />

Portage Lake<br />

(F-400 GAC)<br />

Rhine River<br />

(F-100 GAC)<br />

TRICHLOROETHENE<br />

Source: Zimmer et al. (1988)<br />

Hand et al. (1989)<br />

El- Behlil (1990)<br />

Wausau GW<br />

(F-400 GAC)<br />

Karlsruhe GW<br />

(F-100 GAC)<br />

0 10 20 30 40 50 60 70 80<br />

Preloading Time (weeks)<br />

10


C b<br />

Bulk<br />

Solution<br />

r<br />

C s<br />

Linear<br />

Driving<br />

Force<br />

Boundary<br />

Layer<br />

PSDM MECHANISMS<br />

C p,r<br />

Local Equilibrium<br />

Between Fluid Phase<br />

and Adsorbent Phase<br />

R<br />

Dr<br />

q r<br />

r+Dr<br />

Fluid Phase Adsorbent Phase<br />

Mass<br />

Flux<br />

= k fbCb -Csg<br />

Mass<br />

Flux<br />

q<br />

=-Dsra r<br />

-<br />

∂<br />

∂<br />

r<br />

τ p = 1<br />

De∂C t ∂r<br />

r l p<br />

p<br />

pr ,<br />

Pore<br />

Diffusion<br />

Surface<br />

Diffusion<br />

11


MASS TRANSFER COEFFICIENTS<br />

• External Mass Transfer Coefficient (Gnielinski, 1978)<br />

b g �<br />

k f = 1+1.5 1- e fD<br />

2R<br />

2+0.644 Re Sc<br />

1/ 2 1/ 3<br />

12


MASS TRANSFER COEFFICIENTS (continued)<br />

• Intraparticle Surface Diffusion Coefficient<br />

D = SPDFR<br />

s<br />

L<br />

M<br />

N<br />

D C<br />

�e<br />

p<br />

*<br />

0<br />

KC<br />

1/<br />

n<br />

t p 0<br />

r<br />

– Single Components:<br />

• SPDFR between 4 and 8 (mean = 6.58)<br />

– Multiple Components:<br />

• SPDFR = 16.27 EBCT(min) -0.843<br />

a<br />

O<br />

P<br />

Q<br />

13


MASS TRANSFER COEFFICIENTS (continued)<br />

• Intraparticle Pore Diffusion Coefficient<br />

D =<br />

p<br />

e<br />

p<br />

t<br />

D �<br />

– SOCs Alone (maximum pore diffusion flux):<br />

• τp = 1.0<br />

– SOCs in <strong>the</strong> Presence <strong>of</strong> BOM:<br />

• τp = 1.0 when Time < 70 days<br />

• τp = 0.334 + 6.61(10-6 ) * t when Time > 70 days<br />

p<br />

14


ADSORPTION DESIGN SOFTWARE<br />

(AdDesignS TM )<br />

• Gas and Liquid phase<br />

• Visual Basic Front-End with FORTRAN DLLs<br />

• Up To 6 Components (12 PDEs), Solved by<br />

Orthogonal Collocation (Up To 18 Axial and 6 Radial<br />

Points, Up To 126 ODEs for Each Component, 756<br />

ODEs total)<br />

• Structured Heuristics Based on Experience for Model<br />

Parameter Estimation<br />

• Data Base for Iso<strong>the</strong>rms and Adsorbents<br />

• SI and English Units<br />

• 15,000 lines <strong>of</strong> code<br />

15


Liquid Phase Concentration ( µg/L)<br />

2500<br />

2250<br />

2000<br />

1750<br />

1500<br />

1250<br />

1000<br />

750<br />

500<br />

250<br />

0<br />

CHLOROFORM: 6 Component ECM and<br />

PSDM Simulations for Organic Free Water<br />

EBCT =<br />

2.4 min.<br />

EBCT =<br />

9.56 min.<br />

EBCT =<br />

4.9 min.<br />

ECM<br />

EFFLUENT : EBCT = 2.4 min.<br />

EFFLUENT : EBCT = 4.9 min.<br />

EFFLUENT : EBCT = 9.56 min.<br />

INFLUENT : PILOT SCALE<br />

PSDM : EBCT = 2.4 min.<br />

PSDM : EBCT = 4.90 min.<br />

PSDM : EBCT = 9.56 min.<br />

CHLOROFORM F-400 GAC (12 x 40 mesh)<br />

C0,AVG. = 1020.9 mg/L v = 5.12 m/hr T = 13 o C<br />

Data Source: Arora (1989)<br />

0 5 10 15 20 25 30 35 40 45 50<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

16


Liquid Phase Concentration ( µg/L)<br />

5000<br />

4500<br />

4000<br />

3500<br />

3000<br />

2500<br />

2000<br />

1500<br />

1000<br />

500<br />

1,2-DBE RESULT: 6 Component ECM and<br />

PSDM Simulations for Organic Free Water<br />

0<br />

ECM CALCULATION<br />

EFFLUENT : EBCT = 2.4 min.<br />

EFFLUENT : EBCT = 4.9 min.<br />

EFFLUENT : EBCT = 9.56 min.<br />

INFLUENT : PILOT SCALE<br />

PSDM : EBCT = 2.40 min.<br />

PSDM : EBCT = 4.90 min.<br />

PSDM : EBCT = 9.56 min.<br />

EBCT =<br />

2.4 min.<br />

EBCT =<br />

4.9 min.<br />

1,2-DIBROMOETHANE<br />

F-400 GAC (12 x 40 mesh)<br />

C0,AVG. = 1576.8 µg/L<br />

v = 5.12 m/hr<br />

T = 13 o C<br />

Data Source: Arora (1989)<br />

EBCT =<br />

9.56 min.<br />

0 5 10 15 20 25 30 35 40 45 50<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

17


Liquid Phase Concentration ( µg/L)<br />

TCE RESULT: 6 Component ECM and PSDM<br />

Simulations for Organic Free Water<br />

1500<br />

1350<br />

1200<br />

1050<br />

900<br />

750<br />

600<br />

450<br />

300<br />

150<br />

0<br />

EBCT =<br />

9.56 min.<br />

EBCT =<br />

4.9 min.<br />

EBCT =<br />

2.4 min.<br />

ECM CALCULATION<br />

EFFLUENT : EBCT = 2.4 min.<br />

EFFLUENT : EBCT = 4.9 min.<br />

EFFLUENT : EBCT = 9.56 min.<br />

INFLUENT : PILOT SCALE<br />

PSDM : EBCT = 2.40 min.<br />

PSDM : EBCT = 4.90 min.<br />

PSDM : EBCT = 9.56 min.<br />

TRICHLOROETHENE F-400 GAC (12 x 40 mesh)<br />

C0,AVG. = 1062.6 µg/L v = 5.12 m/hr T = 13 o C<br />

Data Source: Arora (1989)<br />

0 20 40 60 80 100 120 140 160<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

18


MODEL VERIFICATION EFFORT<br />

• 11 Case Studies<br />

•<br />

– 9 Pilot Plant Experiments<br />

– 2 Full-Scale Plants<br />

11 Water Sources (USA, Germany, Ne<strong>the</strong>rlands)<br />

– 8 Groundwaters<br />

– 3 Surface Waters<br />

• 4 Adsorbents<br />

• 50 Empty Bed Contact Times<br />

• 15 Syn<strong>the</strong>tic Organic Chemicals<br />

19


Liquid-Phase Concentration ( µg/L)<br />

TCE: PSDM PREDICTION - KARLSRUHE<br />

TAP WATER CORRELATIONS<br />

200<br />

180<br />

160<br />

140<br />

120<br />

100<br />

80<br />

60<br />

40<br />

20<br />

0<br />

GROUNDWATER : MANNHEIM, GERMANY<br />

TRICHLOROETHENE (C0 = 90 µg/L)<br />

SURROGATE GROUNDWATER : KARLSRUHE, GERMANY<br />

EBCT : 15.6 min. v = 10 m/hr CALGON F-100 GAC<br />

DATA SOURCE: ZIMMER (1988)<br />

Influent Data<br />

Effluent Data<br />

PDM Model Prediction<br />

0 10 20 30 40 50 60 70 80 90<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

20


Liquid-Phase Concentration ( µg/L)<br />

275<br />

250<br />

225<br />

200<br />

175<br />

150<br />

125<br />

100<br />

75<br />

50<br />

25<br />

0<br />

TCE: PSDM PREDICTION - RHINE<br />

RIVER WATER CORRELATIONS<br />

SURFACE WATER : HUDSON RIVER (WATERFORD, NY)<br />

TRICHLOROETHENE (C0 = 121 µg/L)<br />

SURROGATE SURFACE WATER : RHINE RIVER (GERMANY)<br />

EBCT : 16 min. v = 4 m/hr CALGON F-300 GAC<br />

DATA SOURCE: ALBEN ET AL. (1992)<br />

0 10 20 30 40 50 60 70 80 90 100 110<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

Influent Data<br />

Effluent Data<br />

PDM Model Prediction<br />

21


1,2-DCP: PSDM PREDICTION - KARLSRUHE<br />

TAP WATER CORRELATIONS<br />

Liquid-Phase Concentration ( µg/L)<br />

1.5<br />

1.35<br />

1.2<br />

1.05<br />

0.9<br />

0.75<br />

0.6<br />

0.45<br />

0.3<br />

0.15<br />

0<br />

GROUNDWATER : NETHERLANDS<br />

1,2-DICHLOROPROPANE (C0 = 0.5 µg/L)<br />

SURROGATE GROUNDWATER : KARLSRUHE, GERMANY<br />

EBCT : 14.3 min. v = 7.23 m/hr CALGON F-400 GAC<br />

DATA SOURCE: KRUITHOFF ET AL. (1989)<br />

Influent Data<br />

Effluent Data<br />

PDM Model Prediction<br />

0 10 20 30 40 50 60 70 80 90 100<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

22


BENTAZONE: PSDM PREDICTION - KARLSRUHE<br />

TAP WATER CORRELATIONS<br />

Liquid-Phase Concentration ( µg/L)<br />

2<br />

1.8<br />

1.6<br />

1.4<br />

1.2<br />

1<br />

0.8<br />

0.6<br />

0.4<br />

0.2<br />

0<br />

GROUNDWATER : NETHERLANDS<br />

BENTAZONE (C0 = 0.9 µg/L)<br />

SURROGATE GROUNDWATER : KARLSRUHE, GERMANY<br />

EBCT : 10.2 min. v = 9.0 m/hr CALGON F-400 GAC<br />

DATA SOURCE: KRUITHOFF ET AL. (1992)<br />

0 10 20 30 40 50 60 70 80 90 100<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

Influent Data<br />

Effluent Data<br />

PDM Model Prediction<br />

23


ATRAZINE: PSDM PREDICTION - KARLSRUHE<br />

TAP WATER CORRELATIONS<br />

Liquid-Phase Concentration ( µg/L)<br />

22<br />

20<br />

18<br />

16<br />

14<br />

12<br />

10<br />

8<br />

6<br />

4<br />

2<br />

0<br />

SURFACE WATER : HUDSON RIVER (WATERFORD, NY)<br />

ATRAZINE (C0 = 8.4 µg/L)<br />

SURROGATE SURFACE WATER : RHINE RIVER (GERMANY)<br />

EBCT : 16 min. v = 4 m/hr CALGON F-300 GAC<br />

DATA SOURCE: ALBEN ET AL. (1992)<br />

0 5 10 15 20 25 30 35 40 45 50 55 60<br />

Liters <strong>of</strong> Water Treated Per Gram <strong>of</strong> GAC<br />

Influent Data<br />

Effluent Data<br />

PDM Model Prediction<br />

24


CHLOROFORM: PSDM PREDICTION USING THE<br />

RHINE RIVER WATER FOULING CORRELATION<br />

Liquid Phase Concentration ( µg/L)<br />

2000<br />

1750<br />

1500<br />

1250<br />

1000<br />

750<br />

500<br />

250<br />

0<br />

CHLOROFORM<br />

Portage Lake Water, Houghton, MI USA<br />

F-400 GAC (12 x 40 mesh) Co,AVG. = 1021 µg/L<br />

EBCT = 9.78 min. v = 5.18 m/hr T = 16 o C<br />

Data Source: Arora (1989)<br />

PSDM PREDICTION<br />

INFLUENT DATA<br />

EFFLUENT DATA<br />

0 1 2 3 4 5 6 7 8 9 10 11<br />

Liters <strong>of</strong> Water Treated per Gram <strong>of</strong> GAC<br />

25


Liquid Phase Concentration ( µg/L)<br />

TCE: PSDM PREDICTION USING THE RHINE<br />

RIVER WATER FOULING CORRELATION<br />

2000<br />

1750<br />

1500<br />

1250<br />

1000<br />

750<br />

500<br />

250<br />

0<br />

TRICHLOROETHENE<br />

Portage Lake Water, Houghton, MI USA<br />

F-400 GAC (12 x 40 mesh) Co,AVG. = 881 µg/L<br />

EBCT = 9.78 min. v = 5.18 m/hr T = 16 o C<br />

Data Source: Arora (1989)<br />

PSDM PREDICTION<br />

INFLUENT DATA<br />

EFFLUENT DATA<br />

0 5 10 15 20 25 30<br />

Liters <strong>of</strong> Water Treated per Gram <strong>of</strong> GAC<br />

26


CONCLUSIONS<br />

• AdDesignSTM interfaces several <strong>fixed</strong> <strong>bed</strong> adsorption<br />

models, model parameter estimation methods, and<br />

iso<strong>the</strong>rm and adsorbent data bases.<br />

• AdDesignSTM allows <strong>the</strong> user to make adsorber<br />

•<br />

<strong>performance</strong> predictions with greater ease and<br />

archive <strong>the</strong> results.<br />

The heuristics for determining <strong>the</strong> most appropriate<br />

models and parameters should be considered work in<br />

progress and <strong>the</strong> Adsorption Design S<strong>of</strong>tware can be<br />

greatly improved as more information is ga<strong>the</strong>red on<br />

<strong>the</strong> practical application <strong>of</strong> <strong>the</strong> models.<br />

27


CONCLUSIONS (continued)<br />

• Single component iso<strong>the</strong>rm data can be correlated<br />

using <strong>the</strong> intrinsic molar volume and <strong>the</strong> Polanyi<br />

Potential Theory<br />

• Multicomponent equilibria can be predicted from<br />

single solute iso<strong>the</strong>rms using IAST for similar sized<br />

molecules<br />

• The Equilibrium Column Model can predict <strong>the</strong><br />

longest <strong>bed</strong> life and <strong>the</strong> highest overshoot<br />

concentrations for multicomponent mixtures <strong>of</strong> known<br />

components.<br />

28


CONCLUSIONS (continued)<br />

• The PSDM can predict <strong>the</strong> effluent concentration<br />

history pr<strong>of</strong>iles for multicomponent mixtures <strong>of</strong> known<br />

components.<br />

• The PSDM can simulate <strong>the</strong> effluent concentration<br />

history pr<strong>of</strong>iles for SOCs in <strong>the</strong> presence <strong>of</strong> BOM.<br />

– Reductions in capacity and diffusivities which<br />

were estimated from a ground water and surface<br />

water span <strong>the</strong> range <strong>of</strong> <strong>fixed</strong> <strong>bed</strong> data from 11<br />

different studies.<br />

– Additional comparisons are needed to develop<br />

more general guidelines.<br />

29


FURTHER READING<br />

Crittenden, J.C., N.J. Hutzler, D.G. Geyer, J.L. Oravitz, and G. Friedman, "Transport <strong>of</strong><br />

Organic Compounds with Saturated Groundwater Flow: Model Development and<br />

Parameter Sensitivity," Water Resources Research, 22 (3), 271-284 (1986).<br />

Crittenden, J.C., T.F. Speth, D.W. Hand, P.J. Luft, and B. Lykins, "Evaluating Multicomponent<br />

Competition in Fixed Beds," Journal <strong>of</strong> Environmental Engineering, 113 (6),<br />

1363-1375 (1987a).<br />

Crittenden, J.C., D.W. Hand, H. Arora, and B.W. Lykins Jr., "Design Considerations for<br />

GAC Treatment <strong>of</strong> Organic Chemicals," Jour. <strong>of</strong> AWWA, 79 (1), 74-82 (1987b).<br />

Crittenden, J.C., R.D. Cortright, B. Rick, S.R. Tang, and D. Perram, "Using Granular<br />

Activated Carbon to Remove Volatile Organic Chemicals from Air Stripping Off-Gas,"<br />

Jour. <strong>of</strong> AWWA, 80 (5), 73-84 (1988).<br />

Hand, D. W., J. C. Crittenden, and W. E. Thacker, "Simplified Models for Design <strong>of</strong> Fixed-<br />

Bed Adsorbers," Jour. <strong>of</strong> Env. Eng. Div., Proceedings <strong>of</strong> ASCE, 110 (EE2), 1984.<br />

Hand, D. W., J. C. Crittenden, H. Arora, J. Miller, and B.W.Lykins Jr., "Design <strong>of</strong> Fixed-<br />

Beds to Remove Multi-component Mixtures <strong>of</strong> Volatile and Syn<strong>the</strong>tic Organic<br />

Chemicals," Jour. <strong>of</strong> AWWA, 81(1) 1989.<br />

Hand, D. W., J.C. Crittenden, D.R. Hokanson, and J.L. Bulloch, “<strong>Predicting</strong> <strong>the</strong> <strong>performance</strong><br />

<strong>of</strong> <strong>fixed</strong>-<strong>bed</strong> <strong>granular</strong> activated carbon adsorbers,” Water Science and Technology,<br />

35(7), 235-241 (1997).<br />

Son<strong>the</strong>imer, H., J.C. Crittenden, and R.S. Summers, “Activated Carbon for Water<br />

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<strong>of</strong> Germany (1988).<br />

30


ACKNOWLEDGMENTS<br />

• National Center for Clean Industrial and Treatment<br />

Technologies (CenCITT)<br />

• U.S. Environmental Protection Agency<br />

• National Science Foundation (No. ECE 8603615)<br />

• Environmental Engineering Center (MTU)<br />

• Some laboratory and field data were analyzed and<br />

provided by G. Baldauf, Gerhard Zimmer, and <strong>the</strong><br />

late Pr<strong>of</strong>essor Heinrich Son<strong>the</strong>imer at Engler-Bunte-<br />

Institut, University <strong>of</strong> Karlsruhe<br />

31

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