Lessons in Chloramine Residual Management

Chloramination as a disinfection strategy in potable water systems provides benefits such as a lower potential for disinfection by-product formation and improved disinfectant longevity in distribution systems. The significant challenge, however, relates to the shifting chemical equilibrium among ammonia, chlorine, and chloramine species. Premature decay of chloramine compounds can release free ammonia into distribution systems and lead to nitrification and taste and odor issues, as well as other water quality complications.

San Jose Water Company (Partnership for Safe Water & Distribution System Optimization Program subscriber), Aqua Pennsylvania (Partnership for Safe Water subscriber), and East Bay Municipal Utility District (EBMUD) have recently been successful in managing chloramine residuals in problematic reservoirs larger than 5 million gallons. By using a commercial process that manages the desired chloramine residual set point by continuously iterating around the breakpoint curve optimum with a patented chemical feed and mixing strategy, the utilities managed consistent chloramine residuals in challenging and changing environments. During  this webinar, the manufacturer of the process used as well as representatives from the three utilties will detail the residual management process and two case studies.

Chloramines are in use for secondary disinfection by about one third of North American utilities, and the US Environmental Protection Agency expects that rate to increase to more than 60 percent. Management of residual levels to ensure adequate pathogen destruction in distribution systems is challenging, and inadequate control can result in nitrification, or in the alternative, creation of dichloramines and trichloramines, which are responsible for significant taste and odor issues. Utility operators use labor intensive and ultimately ineffective routines to control chloramine levels, such as tank cycling, tank boosting, chlorine burns, and tank dumping, rather than manage the chemical equilibrium in a reservoir. However, the effective recent process used by some of the largest utilities in the country is achieving different outcomes.