Please see Figure 11-4 in MWH, J. C. Crittenden, R. R. Trussell, D. W. Hand, K.
J. Howe, and G. Tchobanoglous, 2005. Water Treatment: Principles and Design ,
Second Edition. John Wiley & Sons, Hoboken, New Jersey.

10
Size Distribution of Typical Naturally Occurring and Processed Filter Sand
Naturally Occurring Sand
1
Processed Filter Sand
0.1
.01 .1 1 5 20 30
Figure by MIT OCW.
Adapted from: MWH, J. C. Crittenden, R. R. Trussell, D. W. Hand, K. J. Howe, and G. Tchobanoglous.
Water Treatment: Principles and Design . 2nd ed. Hoboken, NJ: John Wiley & Sons, 2005, p. 881.

PROPERTY UNIT GARNET LLMENITE SAND
Effective Size, ES mm
Uniformity Coefficient,
UC
UC
0.2 - 0.4
1.3 - 1.7
0.2 - 0.4
1.3 - 1.7
0.4 - 0.8
1.3 - 1.7
ANTHRACITE GAC
0.8 - 2.0
1.3 - 1.7
0.8 - 2.0
1.3 - 2.4
Density,
ρρ
Porosity, ε g/mL 3.6 - 4.2
%
4.5 - 5.0 2.65
45 - 58 Not available 40 - 43
1.4 - 1.8
47 - 52
1.3 - 1.7
Not available
Hardness Moh 6.5 -7.5 5.6
7 2 - 3 Low
Figure by MIT OCW.
Adapted from: MWH, J. C. Crittenden, R. R. Trussell, D. W. Hand, K. J. Howe, and G. Tchobanoglous.
Water Treatment: Principles and Design . 2nd ed. Hoboken, NJ: John Wiley & Sons, 2005, p. 882.

DEVELOPMENT OF NEGATIVE PRESSURE IN THE RAPID GRAVITY FILTER
0
Head Curve - No Flow
WATER
MEDIA
Depth Over which Negative
Pressure Occurs
D
0
5 2
Curve Representing
Increase in Depth to
Clean Sand with Time
1
Head Curves - as Filter
Becomes Dirty
Head Curve -
Clean Filter
4 3
Pressure at Bottom of Media (m of water)
D
Section through filter
Lines 1 to 5 represent the changes in pressure through the filter as the media becomes blinded.
Line 5 results in the development of negative pressures within the media.
Figure by MIT OCW.
Adapted from: Binnie, C., M. Kimber, and G. Smethurst. Basic Water Treatment . 3rd ed.
Cambridge, UK: Royal Society of Chemistry, 2002.

10 0
10 -1
Sum 1
10 -2
Sum 2
10 -3
Interception
10 -4
Sedimentation
ρ
ρ
= 2650 kg/m 3
Diffusion
10 -5
Sedimentation
ρ
ρ
= 1050 kg/m 3
10 -6
10 -8 10 -7 10 -6
Particle Diameter, m
10 -5 10 -4
Influence of Particle Size and Density on Filtration Transport Efficiency (d c
= 0.5 mm, v = 5 m/h, and T = 25 o C)
Figure by MIT OCW.
Adapted from: MWH, J. C. Crittenden, R. R. Trussell, D. W. Hand, K. J. Howe, and G. Tchobanoglous.
Water Treatment: Principles and Design . 2nd ed. Hoboken, NJ: John Wiley & Sons, 2005, p. 912.

Comparison of Theoretical Model and Experimental Data
1
10
-1
10
-2
Experimental Data
10
-3
10
-4
10
-2
10
-1
1
Theoretical Model
10 10
2
100
80
60
Experimental Data
T = 23 o
C
L = 5.5 in. f = 0.36 d = 0.397 mm v
0
= 2 gpm / sq.ft. a = l (assumed)
40
20
Theoretical Model
0
10
-2
10
-1
1 10 10
2
Size of Suspended Particles (microns)
Figure by MIT OCW.
Adapted from: Yao, K.-M., M. T. Habibian, and C. R. O'Melia. "Water and Waste Water Filtration: Concepts and Applications." Environmental Science & Technology 5, no. 11 (November 1971): 1105-1112.

0
0
10
0.5
1
0
10
20
30
40
20
30
α
= 1.0
α
= 0.1
40
50
60
50
60
70
0 0.5
in
1
70
Figure by MIT OCW.
Adapted from: O'Melia, C. R., and J. Y. Shin. Removal of particles using dual media filtration: modeling and experimental studies." Water Science and Technology: Water Supply 1, no. 4, (2001): 73-79.

Wash Trough
Graded Gravel
Filter Media
30 in. max
24 to 30 in.
8 to 16 in.
Underdrain
Figure by MIT OCW.
Adapted from: Binnie, C., M. Kimber, and G. Smethurst. Basic Water Treatment . 3rd ed.
Cambridge, UK: Royal Society of Chemistry, 2002.

Source: JSIM, 2001. Database on Japanese Advanced Environmental Equipment, The Underdrain
System for Rapid Filter and GAC Adsorption Filter. Japan Society of Industrial Machinery
Manufacturers. http://nett21.gec.jp/JSIM_DATA/WATER/WATER_6/html/Doc_307.html. Accessed February 21, 2005.
Typical Pipe Lateral Underdrain Installation
Wash Trough
Filter Media
Gravel layer
Beams
Slit plates
Porous concrete layer
Waste Gullet
Pipe Laterals
Manifold
Source: F.B. Leopold Company, 2003. Filtration, The Process, Underdrain Types.
http://www.fbleopold.com/water/filtration/underdrain.htm. Accessed February 21, 2005.
Figures by MIT OCW.
Source: F.B. Leopold Company, 2003. Filtration, The Process, Underdrain Types.
http://www.fbleopold.com/water/filtration/underdrain.htm. Accessed February 21, 2005.
2