Web-based applications to simulate drinking water inorganic chloramine chemistry.

Two web-based applications (WBAs) relevant to drinking water practice are presented to simulate (1) inorganic chloramine formation and stability, including an example inorganic chloramine demand reaction for organic matter and (2) breakpoint curves. The model underlying both WBAs is a well-established inorganic chloramine formation and decay model. The WBAs were developed to be freely accessible over the Internet as web pages (https://usepaord.shinyapps.io/Unified-Combo/ and https://usepaord.shinyapps.io/Breakpoint-Curve/), providing drinking water practitioners (e.g., operators, regulators, engineers, professors, and students) learning tools to explore inorganic chloramine chemistry in an interactive manner without requiring proprietary software or user modeling expertise. The WBAs allow the user to specify two side-by-side simulations, providing a direct comparison of impacts associated with changing simulation conditions (e.g., free chlorine, free ammonia, and total organic carbon concentrations; pH; total alkalinity; and temperature). Once completed, the user may download simulation data to use offline. The WBAs' implementation, validation, and example simulations are described.