Page 498 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Cake Filtration 453

Sensitivity analysis: Changing the magnitude of one inde-
pendent variable in a mathematical model yields an
associated change in the dependent variable. To
examine the incremental change of a dependent vari-
able caused by a given incremental change to a
selected independent variable is a sensitivity analy-
sis. The sensitivity analysis may be repeated for
as many of the independent variables that are of
interest.
Septum: A screen or porous material used to support the filter
media.
Straining: Retention of particles by a screen or porous media
Acc.V Magn Det 50 μm
15.0 kV 600x BSE in which the pore openings are smaller than the
particles to be removed. A variation of this mechan-
FIGURE 14.G.1 SEM micrograph of perlite filter aid illustrating its ism, that is, physical retention, is what some call
unique morphology; the product was manufactured by Harborlite= being ‘‘embedded.’’ In diatomite filtration, within
World Minerals Inc. (Photo courtesy of Walter Pavlakovich, World the body feed, the particles-to-be-removed, if they
Minerals Inc.=Imerys Corp., Lompoc, CA.) are larger than the adjacent pores within the porous
media, are ‘‘embedded’’ by the particles around.
Voids: The pore space in a filter medium.

TABLE 14.G.2 REFERENCES
Perlite Filter Aid
Baumann, E. R., Diatomite filters for municipal installations, Journal
Particle d(50) Permeability of the American Water Works Association, 49(2):174–186,
Grade Color (mm) (Darcy’s) February 1957.
Baumann, E. R., Diatomite filters for asbestiform fiber removal from
Harborlitet 500 White 32.5 0.5
water, American Water Works Association Conference Pro-
Harborlitet 600 White 33.2 0.8 ceedings, Denver, CO, Paper No. 10-2c, 1975.
Harborlitet 635 White 33.4 1.2 Baumann, E. R., Pre-coat filtration, in R. L. Sanks (Ed.), Water
Harborlitet 700 White 35.6 1.3 Treatment Plant Design, pp. 313–371, Ann Arbor Science
Harborlitet 800 White 36.5 1.7 Publishers, Ann Arbor, MI, 1979.
Harborlitet 900 White 37.4 1.9 Baumann, E. R. and Oulman, C. S., Polyelectrolyte coatings for filter
Harborlitet 1500 White 40.3 2.3 media, 1070 Society Gold Medal Award Paper, Proceedings of
the Filtration Society, Filtration and Separation, Elliccot, MD,
Harborlitet 1800 White 41.8 2.8
7(6):682–690, November=December 1970.
Harborlitet 1900S White 42.5 3.5
Baumann, E. R., Cleasby, J. L., and LaFrenz, R. L., A theory of
Harborlitet 2000 White 43.1 7.0
diatomite filtration, Journal of the American Water Works,
70(9):1109–1119, September 1962.
Source: Courtesy of Walter Pavlakovich, Celite Corp= World Minerals Inc.
Baumann, E. R. et al., Diatomite filters for municipal use, task group
(a division of Imerys Corp.), Lompoc, CA.
report, Journal of the American Water Works Association,
57(2):157–180, 1965.
Bell, G. R., Design criteria for diatomite filters, Journal of the
American Water Works Association, 54(10):1241–1256,
October 1962.
filtration applications. Figure 14.G.1 is a SEM photo- Black, H. H. and Spaulding, C. H., Diatomite water filtration devel-
micrograph illustrating the morphology and size of oped for field troops, Journal of the American Water Works
perlite as a manufactured product. Table 14.G.2 lists Association, 36(11):1208–1221, November 1944.
Bryant, E. A. and Brailey, D., Large-scale ozone-DE filtration: An
size and permeability data for different commercial
industry first, Journal of the American Water Works Associ-
grades of perlite.
ation, 88(11):604–611, November 1980.
Permeability: The property of the filter medium that permits Celite=World Minerals Brochure FA-84A, World Minerals, Inc.,
a fluid to pass through under the influence of differ- www.worldminerals.com, Celite Corp., Lompoc, CA, May 2010.
ential pressure. The ability of a material to permit a Coogan, G. J., Diatomite filtration for removal of iron and manga-
substance to pass through it. nese, Journal of the American Water Works Association,
Porosity: Ratio of volume of voids to total volume of media 54(12):1507–1517, December 1962.
Cummins, A. B., Clarifying efficiency of diatomaceous filter aids,
plus voids.
Industrial and Engineering Chemistry, 34(4):403–411, April
Pre-coat: Initial deposit of media formed by circulation of a 1942.
given mass of charge through the septum area of a tank. Cummins, A. B., Terra Diatomacea, Johns-Manville Corp., Denver,
Pre-coat filtration: Same as cake filtration. CO, 1975 (date estimated).