Polyelectrolyte age and N-nitrosodimethylamine formation in drinking water treatment

Polydiallyldimethylammonium chloride (polyDADMAC) and epichlorohydrin-dimethylamine (Epi-DMA) stock solutions were prepared; stored for varying amounts of time, and used in bench-scale simulations of coagulation/flocculation/sedimentation to determine whether polymer stock age had an influence on NDMA yields. Stock solution ages ranged from under one hour to fifty hours. PolyDADMAC stock age did not significantly affect NDMA production. Epi-DMA stock age significantly increased NDMA production over a time span of 0 to 5 hours, but not from 5 to 50 hours. The relationship between the change in NDMA yields and Epi-DMA stock solution age may be a first-order reaction or a two-phase process. Statistical evaluation of the data available supports both theories.