N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and pKa values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor’s prior chloramination.

ABSTRACT
 1. Introduction
 2. Source and chemical characteristics of NDMA precursors
 3. NDMA formation mechanisms upon chloramination
 4. Mitigation strategies for NDMA formation control
 5. Conclusions
 References

• Mingizem Gashaw Seid(Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Division of Energy and Environment Technology, KIST-School, University of Science and Technology) | 민기
• Aseom Son(Center for Water Resource Cycle Research, Korea Institute of Science and Technology) | 손아섬
• Kangwoo Cho(Division of Environmental Science and Engineering, Pohang University of Science and Technology(POSTECH)) | 조강우
• Seokwon Hong(Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Division of Energy and Environment Technology, KIST-School, University of Science and Technology) | 홍석원 Corresponding author