Page 238 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Coagulation 193

TABLE 9.1
Particles Found in Ambient Water in North America and Their Characteristics
Category Group=Name Size (mm) Zeta Pot. (mV) Counts (#=L)
a
Mineral Clays (kaolinite, montmorillonite) 0.001–1 b 15 to 20 c
8
6
Asbestos fibers—amphibole <2 d Negative d 10 –10 fibers=L e
6
9
Asbestos fibers—chrysotile <2 d Positive d 10 10 fibers=L e
4
Biological Viruses 0.01–0.1 b 10 –10 10
3
Bacteria 0.3–10 f 50 g 10 –10 9
3
Bacillus subtilis spores 18 h 10 –10 5
In raw municipal sewage 200
j
Giardia lamblia cysts 10 i 40 , 14 h 0.1–20
In raw municipal sewage 200
j
Cryptosporidium parvum oocysts 4–5 j,k 35 , 7 h 0.1–20
Algae 30–50 k 3to 30 l 10–10 9m
g l 5m
Diatoms 3–70 3to 30 10–10
Parasite eggs 10–50 k 0.01 n
k n
Nematodes eggs, free living 10 0.01
Nematodes eggs, parasitic 10 k,n 0.001 n
Coccidia 3–10 n 0.01 n
Pollen 30–150 n 1 n
Ciliates 20–800 n 1 n
Crustaceans=eggs 100 n 1 n
Insects 100–1000 n 1 n
Flagellates 5–80 n 1 n
Free-living amoebae 30–30 n 0.1 n
Biological concentrate mixture 13.5 c 10,000 n
Other particles Amorphous debris, small 1–5 j,n 10,000 n
j,n n
Amorphous debris, large 5–500 100
Fecal debris, rodent 50–1000 n 1 l
Organic colloids o 1–100
Color (organic macro-mol.) Negative p
Activated carbon 1–1000 35 j
Source: Adapted from Hendricks et al. Manual of Design for Slow Sand Filtration, AWWA Research Foundation and American Water Works
Association, Denver, CO, 1991.
a
Clays include montmorillonite, kaolinite, and illite, to name a few groups.
b
Tate and Trussel (1978).
c
Al-Jadhai and Hendricks (1989) measured 16.4 mV for water from the Cache La Poudre River having turbidity 0.25 NTU and particle counts
600,063 particles=10 mL using a 70 mm aperture.
d
O’Melia (1979, p. 2). Note that chrysotile is the only particle listed with positive charge. The statements from O’Melia and later from
Schleppenbach, c. 1983, p. 22 on the positive charge were not documented with references and are included to indicate the possibility that some
particles may have positive charge.
e
Logsdon (1979, p. 24 for amphibole, p. 43 for chrysotile).
f
Beard and Tanaka (1977).
g
Bean et al. (1964); range in zeta potential for bacteria was 35 to 70; bacteria species were Balantidium coli, Bacillus subtilis, and Proteus.
h
Fox and Lytle (1996); they detected no discernible effect of pH for Bacillus subtilis spores, for G. lamblia cysts, or C. parvum oocysts over for
4 < pH < 11.
i
Jakubowski and Hoff (1979).
j
Ongerth and Pecoraro (1996), data are for pH ¼ 7.0. Formalin fixed cysts had z ¼ 17 at pH ¼ 7.1.
k
Hibler, C. P., Personal communication (August 23, 1990); note that the list of biological particles cited in footnotes ‘‘k’’ and ‘‘n’’ were as
compiled by Hibler for microscopic examination of cartridge filter samples obtained by water treatment plant operators and sent to Dr. Hibler at
Colorado State University.
l
Cushen (1996).
m
Dr. Paul Kugrens, Professor of Biology, Colorado State University, personal communication, February 15, 2001.
n
Hancock, C. M., Personal communication (February 14 and 19, 2001); concentrations are approximate ‘‘averages’’ based on experience in
microscopic examination of perhaps thousands of samples from ambient waters and will vary with different waters and seasons.
o
Safe Drinking Water Committee (1977) lists but gives no data.
p
Black (1948).