AWWA WQTC71523

This powerpoint presentation begins by providing a brief overview of nitrification and a chloramines dosing strategy to control nitrification. The problem statement asks, "Can excess Cl₂ be added to achieve the target residual at a 5:1 Cl₂:NH₃-N ratio?" A case study of Trinity River water is presented that included previous dosing at a 5:1 applied ratio that resulted in free ammonia in the delivery pipe, and a reduction in NH₃ could save money, but breakpoint rxns are a concern. The experimental methodology included: bench-scale experiment; Cl₂ and NH₃ added to Trinity River water in chlorine demand-free amber glass bottles (250 mL); duplicates conducted for experiments zero (0) and 4; total and free chlorine measurements by DPD method (Hach 8167 and 8021); and, total ammonia by Salicylate Method (Hach 8155). Raw water characteristics are presented, along with chlorine demand in Trinity River water, minimal breakpoint reactions, and disinfection byproducts results. Includes tables, figures.