Surface water supplies the majority of drinking water in the Northeast. Experience with
Riverbank Filtration (RBF) in Europe and more recently in the United States has demonstrated
significant improvements in raw water quality, including removal of natural organic matter
(NOM), biodegradable compounds, pesticides, microbes, and other water quality contaminants
and compensation for shock loads of chemical contaminants (Kuehn & Mueller, 2000; Ray et al.,
2002a; Ray et al., 2002b; Tufenkji et al., 2002; Weiss et al., 2003a; Weiss et al., 2003b). Because
of these potential improvements, regulators and utilities in the United States have recently looked
more strongly at RBF as a means for providing high-quality sources for drinking water.
However, little data are available to compare the performance of RBF with that of conventional
drinking water treatment processes more commonly used in the United States (e.g. coagulation,
flocculation, sedimentation) from identical river water sources, especially with regard to the
removal of organic disinfection byproduct (DBP) precursor material. In addition, little is known
about the extent to which RBF may serve to reliably remove Giardia, Cryptosporidium, and
other pathogens (e.g., bacteria, viruses) from river water. In particular, data are needed on the
transport of microbial pathogens through riverbank systems relative to that of more easily
measured indicator parameters, such as particles and coliform bacteria.
In the above context, research was conducted to document the water quality benefits
during RBF at three major river sources in the mid-western United States (the Ohio River at
Jeffersonville, Indiana; the Wabash River at Terre Haute, Indiana; and the Missouri River at Parkville,
Missouri), specifically with regard to reduction in DBP precursor organic matter and microbial
pathogens. Specific objectives were to:
evaluate the merits of RBF for removing organic DBP precursor material;
evaluate whether RBF can improve finished drinking water quality by removing
and/or altering NOM in a manner that is not otherwise accomplished through conventional
processes of drinking water treatment (e.g. coagulation, flocculation, sedimentation);
evaluate changes in the character of NOM upon ground passage from the river to the
wells;
evaluate the merits of RBF for removing pathogenic microorganisms; and,
compare the transport of microbial pathogens with that of some potential surrogate or
indicator parameters (e.g. particles, turbidity, coliforms, aerobic and anaerobic spores, diatoms,
bacteriophage).
To address objectives 1, 2, and 3, samples of the river source waters and the bank-filtered
well waters from the three study sites were analyzed for a range of water quality parameters
including TOC, DOC, UV-absorbance at 254-nm (UV-254), biodegradable dissolved organic
carbon (BDOC), biologically assimilable organic carbon (AOC), inorganic species, and DBP
formation potential. In the second year of the project, river waters were subjected to a benchscale
conventional treatment train consisting of coagulation, flocculation, sedimentation, glass-fiber
filtration, and ozonation. The treated river waters were compared with the bank-filtered
waters in terms of TOC, DOC, UV-254, and DBP formation potential. In the third and fourth
years of the project, NOM from the river and well waters was characterized using the XAD-8
resin adsorption fractionation method (Leenheer, 1981; Thurman & Malcolm, 1981). XAD-8
adsorbing (hydrophobic) and non-adsorbing (hydrophilic) fractions of the river and well waters
were compared with respect to DOC, UV-254, and DBP formation potential to determine
whether RBF alters the character of the source water NOM upon ground passage and if so, which
fractions are preferentially removed.
The ongoing research to address objectives 4 and 5 consists of: field studies at the three
study sites to document actual changes in microorganism concentrations upon subsurface travel
between the r
| Edition : | Vol. - No. |
| File Size : | 1
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| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 5 |
| Published : | 11/02/2003 |
