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COMPARING RBF WITH BENCH-SCALE CONVENTIONAL TREATMENT FOR PRECURSOR REDUCTION
Citation:
Weiss, W. J., E. Bouwer, W. P. Ball, C. R. O'Melia, H. Arora, AND T F. Speth*. COMPARING RBF WITH BENCH-SCALE CONVENTIONAL TREATMENT FOR PRECURSOR REDUCTION. Lacey, M. (ed.), JOURNAL OF AMERIAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, 95(12):67-80.
Description:
The reduction of disinfection by-product (DBP) precursors upon riverbank filtration (RBF) at three drinking water utilities in the mid-Western United States was compared with that obtained using a bench-scale conventional treatment train on the corresponding river waters. The river waters were subjected to a treatment train consisting of coagulation, flocculation, sedimentation, filtration, and ozonation. All bench-scale treated and bank-filtered waters were chlorinated under two sets of controlled conditions (FP and UFC tests; see text) in order to quantify reductions in DBP precursor material. RBF performed as well as or better than the bench-scale conventional treatment with respect to DBP precursor removal. Total and dissolved organic carbon concentrations were reduced by 20 to 50% upon bench-scale treatment, compared with reductions between 30 and 70% upon subsurface travel to the closer wells at the three sites. Reductions in precursor material for a variety of DBPs (trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate, and chloropicrin) upon bench-scale treatment were generally in the range of 40 to 80%, while reductions upon RBF ranged from 50 to 100%. A shift was observed upon RBF and bench-scale treatment from the chlorinated to the more brominated DBP species, with the shift more pronounced for the bank-filtered waters. This shift was likely due to the increase in the bromide to dissolved organic carbon (DOC) ratio.