292
H. S. Weinberg
advanced separation technology using a single barrier of porous (generally
polymeric) material. The submicron pore size of the filtration media allows
removal of colloidal material, including iron and manganese precipitates as well as
water-borne pathogens, such as Giardia, Cryptosporidium, and bacteria. This
"physical disinfection" capability is important for groundwater supplies under the
influence (GWUI) of surface waters, and UF membranes with nominal pore sizes
of 0.01 ~m, in particular, have been shown to be absolute barriers to viruses
(Jacangelo et al. 1995). The technology has demonstrated effectiveness that is not
compromised by high ranges in turbidity. Moreover, when used for surface-water
treatment, powdered activated carbon can be injected into the influent water to the
membrane when removal of dissolved organic carbon is required, as illustrated in
Figs. 4 and 5.
PAC
oagulant/Llme
MlcroflltraUon
RA W~---,:----:~
WATER
~----~
Waste
Sludge
Ammonia/Chlorine
!
Clearwcll
1---_ _ " DISTRIBUTION SYSTEM
Fig. 4. Settled water micro filtration