Page 476 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Cake Filtration 431

there is a trade-off between low effluent particle concentra-
BOX 14.3 ROBERT BAUMANN
tions and a higher rate-of-headloss increase (McIndoe,
Professor E. Robert Baumann (b. 1921) is listed in 1969a, p. 52).
Who’s Who in America, 56th edition (2002) as ‘‘envir-
onmental engineering educator.’’ Regarding diatomite
filtration, he has had a sustained role in the field starting 14.2.1 PARTICLE REMOVAL EFFECTIVENESS
in 1946 at the University of Illinois and continuing
Suspended particles that may be removed by diatomite filtra-
until about 1979 when he wrote a definitive chapter
tion include iron and manganese oxides, residual solids from
(Baumann 1979) on the topic in Water Treatment
lime-soda softening, algae, bacteria, cysts and oocysts, and
Plant Design (Sanks, 1979). His work has delineated
amorphous organic matter (McIndoe, 1969b, p. 49). The
most of the guidelines that are established that have
lower limit of particle size that may be removed by the finest
made possible the technology as we know it today. He
grade of diatomite is perhaps 0.1–1 mm (McIndoe, 1969b,
moved to Iowa State University in 1953 after complet-
p. 50). The use of alum or polymer-coated diatomite adds to
ing his doctorate at Illinois, retiring as Distinguished
the removal effectiveness, for example, mineral colloids, vir-
Professor Emeritus in 1991, becoming a full-time con-
uses, bacteria, but results in a higher rate of headloss. Alter-
sultant. His work in diatomite filtration has probably
natively, for episodes of higher turbidity, a finer grade of DE
been eclipsed by accomplishments in research, teach-
may be kept on hand (Logsdon, 2008, p. 245).
ing, writing textbooks, consulting, and in leadership
positions in several professional societies. Numerous 14.2.1.1 Turbidity and Bacteria
awards have attested to his prominence in both water
treatment and wastewater treatment, and teaching. His Figure 14.7 shows removals of turbidity, standard plate count
photograph is c. 1960. (SPC) bacteria, and coliforms, plotted as a function median
particle size (showing also the corresponding grade of diatom-
ite). The plots were from experimental work by Lange et al.
2
2
(1984) with data generated by seeding a 0.093 m (1.0 ft )
septum area diatomite pilot plant with HLR ¼ 2.44 m=h
2
(1.0 gpm=ft ). As seen, removals were about 3-log for the
1.0

SPC
Coliforms
0.8

Removal fraction 0.6 Turbidity

14.1.4.3.3 Further Research 0.4
The CSU research was followed by a microscopic analysis
of removal mechanisms by Harris Walton (1988) of Johns- Abbreviations
0.2 Filter: Filter-Cel
Manville; further work was done on alum and cationic addi- Super: Standard Super-Cel
tives by Schuler and Ghosh (1990). Work on removals of Hyflo: Hyflo Super-Cel
C. parvum oocysts was sponsored by IDPA which found SPC: Standard plate count
0.0
log R(oocysts) 4 (Ongerth and Hutton, 1997, 2001). 0 5 10 15 20 25 30
Filter
DE grade: Super C-512 Hyflo C-503 C-535 C-545
14.2 CAKE FILTRATION PROCESS Median particle size (μm)

In DE filtration, it is axiomatic that the grade selected must
FIGURE 14.7 Removals of particles as affected by DE grade.
be smaller in pore size than the size range of the particles to
(Adapted from Lange, K.P. et al., Removal of Gairdia Lamblia cysts
be removed. On the other hand, a grade that is fine enough
and other substances, Diatomaceous Earth Filtration,Vol. 1, Munici-
to remove particles in all categories of interest, especially pal Environmental Research Laboratory, United State Environmental
fine turbidity, viruses, and bacteria will, more than likely, Protection Agency, EPA-600=S2-84-114 (available from NTIS Order
cause a higher-than-desired rate of headloss increase. Thus, No. 84-212 703), September 1984, pp. 66–67.)