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.

.01 .1 1 5 10 50 90 95 99 99.9 99.99 0.1

1

10

Percent of Media with Smaller Diameter

Naturally Occurring Sand

Processed Filter Sand

20 30 70 80

Par

ticl

e D

iam

eter

, m

m

Size Distribution of Typical Naturally Occurring and Processed Filter Sand

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.

Typical properties of filter media used in rapid filters*

PROPERTY UNIT GARNET LLMENITE SAND ANTHRACITE GAC

Effective Size, ES mm 0.2 - 0.4 0.2 - 0.4 0.4 - 0.8 0.8 - 2.0 0.8 - 2.0

Uniformity Coefficient,

UCUC 1.3 - 1.7 1.3 - 1.7 1.3 - 1.7 1.3 - 1.7 1.3 - 2.4

Density, ρρ g/mL 3.6 - 4.2 4.5 - 5.0 2.65 1.4 - 1.8 1.3 - 1.7

Porosity, ε % 45 - 58 Not available 40 - 43 47 - 52 Not

available

Hardness Moh 6.5 -7.5 5.6 7 2 - 3 Low

* = Not Available

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.

5 4 3 2 1

Section through filterPressure at Bottom of Media (m of water)

0

0

D

D

Head Curves - as Filter

Becomes Dirty

Head Curve -

Clean Filter

Head Curve - No Flow

Depth Over

which Negative

Pressure Occurs

Curve Representing

Increase in Depth to

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.

MEDIA

Clean Sand with Time

Dep

th o

f W

ater

(m

)

DEVELOPMENT OF NEGATIVE PRESSURE IN THE RAPID GRAVITY FILTER

WATER

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.

100

10-1

10-2

10-3

10-4

10-5

10-6

10-8 10-7 10-6 10-5 10-4

Sedimentation ρρ = 2650 kg/m3

Sedimentation ρρ = 1050 kg/m3

Sum 2

Sum 1

Interception

c = 0.5 mm, v = 5 m/h, oC)

Particle Diameter, m

Diffusion

Influence of Particle Size and Density on Filtration Transport Efficiency (d

and T = 25

Tra

nsp

ort

Eff

icie

ncy

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.

10-2

10-2

102

102

10-4

10-3

10-2

10-1

10-1

10-1

1

1

1

10

10

0

20

40

60

80

100

Experimental Data

Theoretical Model

d = 0.397 mm

oC

f = 0.36

v0 = 2 gpm / sq.ft.

a = l (assumed)

Size of Suspended Particles (microns)

Experimental Data

Theoretical Model

T = 23

L = 5.5 in.

Rem

oval

Eff

icie

ncy

of

Fil

ter

(%)

Sin

gle

- C

oll

ecto

r E

ffic

iency

Comparison of Theoretical Model and Experimental Data

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.

70

60

50

40

30

20

10

0

70

60

50

40

30

20

10

0

0 0.5 1

0 0.5 1

Dep

th (

cm)

Sand

Anthracite

α = 1.0

α = 0.1

Figure by MIT OCW.

Filter Quality C/C in

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.

Filter Media

Graded Gravel

Underdrain

30 in. max

24 to 30 in.

8 to 16 in.

Wash Trough

Cross Section of a Granular- Media Gravity Filter

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.

2

Slit platesGravel layer

Beams

Porous concrete

layer

Figures by MIT OCW.

Wash Trough

Typical Pipe Lateral Underdrain Installation

Filter Media

Manifold

Pipe Laterals

Waste Gullet

Source: F.B. Leopold Company, 2003. Filtration, The Process, Underdrain Types.

http://www.fbleopold.com/water/filtration/underdrain.htm. Accessed February 21, 2005.

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.

Source: F.B. Leopold Company, 2003. Filtration, The Process, Underdrain Types.

http://www.fbleopold.com/water/filtration/underdrain.htm. Accessed February 21, 2005.