Formation, Detection and Removal of NDMA in Water Treatment Process

Abstract

N-Nitrosodimethylamine(NDMA) is known as a carcinogenic and mutagenic compound ,and in recent years, it has been found to be a novel disinfection by-product of the chloramination process.The NDMA precursors are considered as dimethylamine(DMA) and tertiary amines with dimethylamine functional groups. There are four pathways to NDMA formation: nitrosation, unsymmetrical dimethylhydrazine(UDMH) oxidation, chlorinated UDMH oxidation and hydroxylamine pathway. Formation of NDMA is affected by the presence of free chlorine and bromide, and pH is also a sensitive fator.The detection and analytical methods of NDMA are usually spectrophotometry，thin-layer chromatography, GC, LC and GC/MS.To improve the detection precision, GC/MS/MS and GC/HRMS are applied in detecting the trace NDMA. The methods of NDMA removal are UV degradation, the resin and several types of zeolite adsorption, UV/ozone and UV/hydrogen peroxide advanced oxidation technologies. Ozone also can oxidate percursors,so it can control the NDMA yield indirectly.