Date of Graduation
5-2026
Document Type
Thesis
Degree Name
Bachelor of Science in Civil Engineering
Degree Level
Undergraduate
Department
Civil Engineering
Advisor/Mentor
Julian L. Fairey
Abstract
Chloronitramide anion was recently identified as a decomposition product of inorganic chloramines. Tap‑water concentrations > 300 μg/L reported in a recent study prompted this investigation of chloronitramide anion during monochloramine formation under conditions relevant to drinking water treatment plants. As monochloramine is formed by mixing free chlorine with free ammonia, the impacts of pH, reagent mixing intensity, and reagent addition order were assessed on monochloramine and chloronitramide anion yields. Jar tests were conducted in distilled deionized water at target pH levels of 7 and 9 under rapid, slow, and no‑mixing conditions, with alternating reagent order addition and a target monochloramine dose of 4 mg/L as Cl2. Additional jar tests were completed using partially treated raw water from a city in Texas that contained natural organic matter.
Results indicate that chloronitramide anion does not form in significant concentrations following monochloramine formation under typical treatment plant conditions. However, no reagent mixing decreased monochloramine yields by about one-half, and at pH 9 about 6–20 μg/L chloronitramide anion formed under the no mixing condition. At pH 7, similar levels of chloronitramide anion were observed but are attributed primarily to monochloramine decay. In the partially treated raw water from Texas, chloronitramide anion formed at quantifiable levels in two of twelve jar tests at about 15–20 μg/L. Importantly, reagent addition order impacted monochloramine yields, with free chlorine‑first addition resulting in about 2.2 mg/L as Cl2 even under rapid mixing conditions compared to about 3.5 mg/L as Cl2 for free ammonia first addition. This study demonstrates that poor reagent mixing decreases monochloramine yields but does not appreciably increase chloronitramide anion formation.
Keywords
Water Treatment; Chloramines; Monochloramine; Disinfection Byproducts; Chloronitramide Anion
Citation
Johnson, B. E., Fairey, J. L., & Thornhill, J. A. (2026). Chloronitramide Anion Yields During Monochloramine Formation: Impact of Reagent Addition Order, pH, and Mixing. Civil Engineering Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/cveguht/93
