AWWA WQTC58964

Surface water supplies the majority of drinking water in the Northeast. Experience withRiverbank Filtration (RBF) in Europe and more recently in the United States has demonstratedsignificant improvements in raw water quality, including removal of natural organic matter(NOM), biodegradable compounds, pesticides, microbes, and other water quality contaminantsand 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). Becauseof these potential improvements, regulators and utilities in the United States have recently lookedmore 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 conventionaldrinking water treatment processes more commonly used in the United States (e.g. coagulation,flocculation, sedimentation) from identical river water sources, especially with regard to theremoval of organic disinfection byproduct (DBP) precursor material. In addition, little is knownabout the extent to which RBF may serve to reliably remove Giardia, Cryptosporidium, andother pathogens (e.g., bacteria, viruses) from river water. In particular, data are needed on thetransport of microbial pathogens through riverbank systems relative to that of more easilymeasured indicator parameters, such as particles and coliform bacteria.In the above context, research was conducted to document the water quality benefitsduring RBF at three major river sources in the mid-western United States (the Ohio River atJeffersonville, 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 microbialpathogens. 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 removingand/or altering NOM in a manner that is not otherwise accomplished through conventionalprocesses of drinking water treatment (e.g. coagulation, flocculation, sedimentation);evaluate changes in the character of NOM upon ground passage from the river to thewells;evaluate the merits of RBF for removing pathogenic microorganisms; and,compare the transport of microbial pathogens with that of some potential surrogate orindicator 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-filteredwell waters from the three study sites were analyzed for a range of water quality parametersincluding TOC, DOC, UV-absorbance at 254-nm (UV-254), biodegradable dissolved organiccarbon (BDOC), biologically assimilable organic carbon (AOC), inorganic species, and DBPformation potential. In the second year of the project, river waters were subjected to a benchscaleconventional treatment train consisting of coagulation, flocculation, sedimentation, glass-fiberfiltration, and ozonation. The treated river waters were compared with the bank-filteredwaters in terms of TOC, DOC, UV-254, and DBP formation potential. In the third and fourthyears of the project, NOM from the river and well waters was characterized using the XAD-8resin adsorption fractionation method (Leenheer, 1981; Thurman & Malcolm, 1981). XAD-8adsorbing (hydrophobic) and non-adsorbing (hydrophilic) fractions of the river and well waterswere compared with respect to DOC, UV-254, and DBP formation potential to determinewhether RBF alters the character of the source water NOM upon ground passage and if so, whichfractions are preferentially removed.The ongoing research to address objectives 4 and 5 consists of: field studies at the threestudy sites to document actual changes in microorganism concentrations upon subsurface travelbetween the r

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

5

File Size:

1 file , 260 KB