NDMA formation potential removal in treated effluent by UV/H2O2 process

NDMA formation from treated wastewater is one of the concerns in water reuse. This study focused on NDMA formation potential (NDMAFP) removal in wastewater treated effluent by UV/H2O2 technology. A UV/H2O2 system was tested for the removal performance on both organic precursors and NDMAFP. The system consisted of a low pressure ultra-violet (LPUV) with an intensity of 2 mW/cm2 and a H2O2 dosage of 100 ppm. Reaction time was 60 minutes. Two types of wastewater treated effluents were collected: activated sludge process (ASP) effluent and membrane bio-reactor (MBR) effluent. Results showed efficient dissolved organic carbon (DOC) removal (70%). Dissolved organic nitrogen (DON) removal was less efficient (20–30%). Eighty per cent of NDMAFP in ASP effluent was removed within 1 hour. However, no NDMAFP removal was discovered in MBR effluent. This indicated that the effect of the UV/H2O2 system on NDMAFP removal was water specific. A generation of intermediate NDMA precursors was observed in the ASP effluent. Results indicated that sufficient oxidation should be provided to reduce intermediate NDMA precursors and to achieve NDMAFP removal.