Citation:

Kennicutt, A., P. Rossman, J. Bollman, T. Aho, G. Abulikemu, J. Pressman, AND D. Wahman. Evaluation of Preformed Monochloramine Reactivity with Processed Natural Organic Matter and Scaling Methodology Development for Concentrated Waters. ACS ES&T Water. American Chemical Society, Washington, DC, 2(12):2431-2440, (2022). https://doi.org/10.1021/acsestwater.2c00292

Impact/Purpose:

The environmental or health problem addressed by the study: Preformed monochloramine reactivity in natural and concentrated waters. A general description of the work and results: Experiments have been conducted to evaluate preformed monochloramine reactivity in natural and concentrated waters. The long-term importance or significance of the findings: Provides guidance on impacts of natural organic matter processing on preformed monochlormaine reactivity and designing experiments in concentrated waters. Who would be interested in or could apply the results (e.g. program or regional partners, general public, local communities): Researchers conducting work with monochloramine and forming disinfectant byproduct mixtures in concentrated waters. 

Description:

To evaluate natural organic matter (NOM) processing impacts on preformed monochloramine (PM) reactivity and as a first step in creating concentrated disinfection byproduct (DBP) mixtures from PM, a rational methodology was developed to proportionally scale PM NOM related demand in unconcentrated source waters to waters with concentrated NOM.  Multiple NOM preparations were evaluated, including a liquid concentrate and reconstituted lyophilized solid material.  Published kinetic models were evaluated and used to develop a focused reaction scheme (FRS) that was relatively simple to implement and focused on monochloramine loss, including considerations for inorganic chloramine stability (i.e., inorganic autodecomposition) and bromide and iodide impacts.  The FRS included critical reaction pathways and accurately simulated (without modification) monochloramine experimental data with and without bromide and iodide present over a wide range of PM-dosed NOM-free waters.  For NOM-containing waters, the addition of two NOM reactions in the FRS allowed (i) apportioning of monochloramine loss to either inorganic or NOM related reactions and (ii) selecting experiment conditions to provide an equivalent monochloramine NOM related demand in unconcentrated and concentrated waters.  The methodology provides a framework for future experimentation to evaluate the scaling of DBPs and their speciation in concentrated water matrices when providing an equivalent NOM-related monochloramine demand in unconcentrated and concentrated matrices.

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