Formation mechanism and control strategies of yN-nitrosodimethylamine (NDMA) formation during ozonation

This review summarizes major findings over the last decade related to N-nitrosodimethylamine (NDMA) formed upon ozonation, which was regarded as highly toxic and carcinogenic disinfection by-products. The reaction kinetics, chem-ical yields and mechanisms were assessed for the ozonation of potential precursors including dimethylamine (DMA), N,N-dimethylsulfamide, hydrazines, N-containing water and wastewater polymers, dyes containing a dimethylamino function, N-functionalized carbon nanotubes, guanidine, and phenylurea. The effects of bromide on the NDMA formation during ozonation of different types of precursors were also discussed. The mechanism for NDMA formation during ozonation of DMA was re-summarized and new perspectives were proposed to assess on this mechanism. Effect of hydroxyl radicals (center dot OH) on NDMA formation during ozonation was also discussed due to the noticeable oxidation of NDMA by center dot OH. Surrogate parameters including nitrate formation and UV254 after ozonation may be useful parameters to estimate NDMA formation for practical application. The strategies for NDMA formation control were proposed through improving the ozonation process such as ozone/hydrogen peroxide, ozone/peroxymonosulfate and catalytic ozonation process based on membrane pores aeration (MEMBRO3X).

Automated summary

This review summarizes the major findings regarding the formation of N-nitrosodimethylamine (NDMA) during ozonation, a highly toxic and carcinogenic disinfection by-product. It evaluates the reaction kinetics, chemical yields, and mechanisms of potential precursors, as well as proposes strategies for controlling NDMA formation through improved ozonation processes.