Alternative application of preformed monochloramine as a drinking water disinfectant for redosing in long drinking water distribution system servicing remote locations. (15th October 2020)

• Record Type: Journal Article
• Authors: Allard, Sébastien; Kristiana, Ina; Andringa-Bate, Charlotte; Joll, Cynthia A.
• Is Part Of: Water research. Volume 185(2020)
• Publication Date: 2020-10-15
• Subjects: Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.116083
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Chloramine is the disinfectant of choice for long drinking water distribution systems since it is more stable than chlorine, therefore providing a longer lasting disinfectant residual and producing less disinfection byproducts. However, to deliver safe drinking water in remote areas, redosing stations are used where (mostly) chlorine is added to the water to re-establish a disinfectant residual. In this study, the use of a highly concentrated preformed monochloramine solution instead of chlorine for redosing in tanks or reservoirs along extensive distribution systems was investigated. This will avoid unwanted reactions due to chlorine reactivity (formation of disinfection byproducts) and increase the disinfectant stability. Highly concentrated monochloramine solutions (15 mM, 1 gCl2 L −1 ) are most stable at high pH (10) and low temperature. It was found that the current kinetic model used for drinking water application was not accurate for highly concentrated monochloramine. A simplified kinetic model was developed and successfully used to predict monochloramine stability in our conditions. This will assist water utilities for application of preformed concentrated monochloramine allowing monochloramine redosing in long drinking water distribution systems. Hydrazine, a compound of health concern, might form at high monochloramine concentrations and high pH and needs to be carefully controlled. Graphical abstract: Image 1 Highlights: Redosing with monochloramine instead of chlorine in remote areas is feasible. Highly concentrated monochloramine solution (15 mM) are stable at high pHs. Kinetic model successfully predicts monochloramine stability at high concentrations. The formation of hydrazine needs to be carefully controlled. Preformed concentrated monochloramine is a viable option for water utilities.