Citation:

Do, T., J. Fairey, A. Pifer, D. Wahman, AND W. Zhang. Assessing Fluorescence as an Early-Warning Indicator of Biological Ammonia Oxidation in Chloraminated Water: Laboratory-Scale Annular Reactor Studies with a Benchtop Fluorometer. Water Research Foundation, Denver, CO, (2020).

Impact/Purpose:

The environmental or health problem addressed by the study: A method to provide early detection of nitrification in drinking water A general description of the work and results: Experiments have been conducted to evaluate the fluorescent signal that can be used to provide the early detection of nitrification in drinking water The long term importance or significance of the findings: Provides a method to early detect nitrification Who would be interested in or could apply the results (e.g. program or regional partners, general public, local communities): Drinking water utilities

Description:

This project identified and validated fluorescence intensity at specific wavelength pairs (IEX/EM) for early detection of nitrification in chloraminated distribution systems. Thirteen biofilm annular reactor (AnR) tests were completed using feedwaters from Fayetteville (FW-F), Dallas (FW-D), and Houston (FW-H). Following a period of biological stability (Phase 1), chemical conditions were made conducive to nitrification (Phase 2), prior to biological ammonia oxidation (Phase 3). A corrective action threshold (CAT) was established during Phase 1 for each IEX/EM. In ten AnR tests with FW-D and FW-H, the effluent I230/345 (PRI) and influent-subtracted PRI (ΔPRI) exceeded the CAT in approximately 50% of the days in Phase 2 (n = 78). The median times between the first CAT exceedances and measurable nitrite production were 4.5 and 7.0 days for PRI and ΔPRI, respectively. The CAT was not exceeded during Phase 2 with FW-F likely because of the low organic carbon content of this feedwater, implicating organics released by the faster growing heterotrophs as the source of the increased PRI and ΔPRI signals. Further exceedances of the CAT in Phase 3 were observed in all three source waters, amplified by increasing nitrite concentrations.

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